THE XIIth SYMPOSIUM ON EARTH'S PHYSICS
AND APPLIED GEOPHYSICS

The Academy of the Socialist Republic of Romania organized, within the period 20th to 22nd December 1982, through he Romanian National Committee of Geodesy and Geophysics, under the presidence of the academician Sabba Stefanescu, the XIIth Symposium of Earth's Physics and Applied Geophysics and the Ist National Exhibition of instrument in the corresponding fields.
In the opening session the introductory address by acad. Sabba Stefanescu, president of the Romanian National Committee of Geodesy and Geophysics, was followed by the greeting speeches pronounced by dr. Ioan Folea, Minister of Geology, and dr. Marin Ivascu, General Director of the Central Institute of Physics, and three papers of general interest.
The sessions of the symposium, chaired by members and corresponding members of the Academy, were held in three sections:
First Section: Geophysical investigations for energy resources and engineering geophysics (chairman professor Radu Botezatu, corresponding member of the Academy);
Second Section: Geophysical investigations for solid mineral substances (under the chairmanship of academician Sabba Stefanescu);
Third Section: Earth's Physics and Geodesy researches (chairman professor Liviu Constantinescu, corresponding member of the Academy).
It is to be mentioned that the papers of the third section were partly presented in the form of posters in the apparatus exhibition.
During the closing session of the symposium the participants paid due homage to the president of the Romanian National Committee of Geodesy and Geophysics, academician Sabba Stefanescu, the undisputed head of the Romanian geophysical school, who in 1982 reached the venerable age of 80 years.
In order to give the specialists not able to attend these manifestations the possibility to become acquainted with the main directions of development of the scientific researches in the fields of the Earth's physics and applied geophysics, the abstracts of the 105 papers and 23 instruments presented are given in the following, each abstract being accompanied by the keywords for a better contouring of the area of interest.

OPENING SESSION

DISTRIBUTION OF THE Z MAGNETIC ANOMALIES
OVER THE TERRITORY OF ROMANIA

T. AILENEI1, SC. STOENESCU2, GEORGETA VELCESCU2, D. ROMANESCU2,
M.VISARION2, S. RADAN2, M. ROTH2, L. BESUTIU2, GEORGETA BESUTIU2
1Faculty of Geology and Geography, Bucharest University, Bucharest
2Institute of Geology and Geophysics, Bucharest

The magnetic map of Romania in the Z and Za versions is the result of an activity carried out for over 20 years.
The paper presents metrological and methodological information as well as aspects concerning the primary data processing.
The images obtained, by their rich informational content, contribute to the enlargement of the knowledge of the deep geological structure of Romania.
Key words: magnetic maps, magnetic anomalies, data processing, deep geological structure.

SEISMOTECTONIC MAP OF ROMANIA

I. CORNEA1, V. LAZARESCU2, C. RADU1
1Centre for Earth Physics and Seismology, Bucharest – Magurele
2Faculty of Geology and Geography, Bucharest University, Bucharest

The seismotectonic maps of Romania (1972 – 1978), drawn up in a conventional manner (earthquake epicentres against a structural background), and a new colour version introduced by the authors in Leeds (1982) are successively presented. The basis of the new map is the highest seismic intensity observed, overlain by neotectonic and recent deformations, plus epicentres indicated differentially according to several criteria.
Key words: interal geodynamics; tectonics; seismoloy; maps, earthquake parameters.

SPACE IMAGE USES IN MONITORING THE EARTH AS A PLANET

N. ZEGHERU, M. ALBOTA
Institute of Photogrametry, Geodesy, cartography and Territory Organization, Bucharest

The use of the space photographic and non-photographic images in investigating the terrestrial surface, the surface and underground resources, as well as in environmental monitoring has become a usual atractivity. The investigation of the Earth as a planet, using the same means, has been recently initiated. The terrestrial crust changes and seismic activity, continental displacements, global Earth monitoring, fault and ice cap dynamics, coastal zone evolutions and the ground-water distribution, etc. Are dwelt upon in this paper.
Key words: Earth's space images, environmental monitoring, terrestrial crust changes, seismic activity, continental displacements.

I-st SECTION

GEOPHYSICAL INVESTIGATIONS FOR ENERGY
RESOURCES AND ENGINEERING GEOPHYSICS

Chairman: prof. RADU BOTEZATU, corresponding member of the Academy

TRACE INTERPOLATION OF SEISMIC DATA

V. BARDAN
Enterprise of Geological and Geophysical Surveys, Bucharest

In the design of a seismic survey, the proper choice of the spatial sampling interval is a matter of great practical importance. Benefits of dense spatial sampling must be weighted against costs of data acquiring and processing. All standard methods of migration yield poor results when sampling is too coarse. Interpolation of traces provides a workable alternative. In this paper are presented some remarks and results regarding sin x/x interpolation of traces.
Key words: seismic data, spatial sampling interval, migration, traces interpolation.

ABOUT THE QUANTITATIVE WELL LOGG EVALUATION RECORDED
IN TIGHT AND FISSURED CARBONATE ROCKS

V. NEGOITA
Oil and Gas Research Institute, Campina, Prahova County, Romania

The first part of the paper presents a petrophysical characterization of carbonate rocks based on logs from the Moesian Platform.
The second part of the paper shows how fissure existence, their orientation and fluid influence the well log values.
Key words: well logging, quantitative interpretation, logs, tight rocks, fissured rocks.

INTEGRATION OF MAGNETIC PROSPECTING IN THE RESEARCH
PERFORMED FOR DISCOVERING NEW HYDROCARBON DEPOSITS

D. MILCOVEANU
Institute for Under-Engineering Education, Hunedoara, Romania

The present paper is concerned with the study of the dominant role of igneous intrusions (hot magma) that may be considered as heat generators, in the genesis and migration of hydrocarbons. The detection of prospecting and the correlation of the magnetic maxima with the distribution of hydrocarbon deposits are emphasized.
Key words: igneous intrusions, hot magma, hydrocarbon migration, magnetic prospecting

NON-LINEAR DECONVOLUTION

C. STAN
Enterprise of Geological and Geophysical Surveys, Bucharest

A type of iterative deconvolution that extracts the source waveform and the reflectivity from a seismogram through the use of zero memory non-linear estimator of the reflection coefficient amplitude is developed. Here we present a theory for iterative deconvolution that is based upon the specification of a stochastic model describing reflectivity.
Key words: non-linear deconvolution, gaussian process, stochastic model, non-liner estimator, density of probability, inverse filter, reflection coefficient

2-D AND 3-D ALGORITHMS FOR COMPUTING INTERVAL VELOCITIES

P. STINGESCU
Enterprise of Geological and Geophysical Surveys, Bucharest

Various Dix-type formulae for 2-D and 3-D models that can be used to compute interval velocities and recover the depth model from surface measurements are discussed.
Key words: interval velocities, ray tracing, normal time, normal move-out, time slope, azimuth, dip, strike.

BOX-JENKINS DECONVOLUTION

ROZALIA IONESCU
Enterprise of Geological and Geophysical Surveys, Bucharest

This paper describes a predictive deconvolution method based on dynamic series analysis, in which prediction operators may be viewed as deconvolution operators issued from a mathematical model described by Box and Jenkins (Time Series Analysis Forecasting and Control, 1970 – 1971).
Key words: seismic data, predictive deconvolution, model identification, preliminary estimation, efficient estimation, model checking.

ELASTIC WAVE PROPAGATION IN FLUID MEDIUM OF HIGH VISCOSITY,
WITH ABSORPTION AND DISPERSION EFFECT

F. NICHIFOR
Enterprise of Geological and Geophysical Surveys, Bucharest

By presenting a model of an absorbant medium (a model for which the amplitude of elastic waves has an exponential decrease in terms of distance: A = A0 e), we want to compute the value of the absorption coefficient and its dependence on the status parameters of the fluid medium of high viscosity.
Key words: elastic wave, fluid medium, absorption coefficient, reflection coefficient, quality factor, fluid medium of high viscosity.

MATRIX INFORMATION STATISTICS
APPLICATIONS. MICROTECTONIC STRUCTURES

D. BERSADSCHI
Chem. Ind. Ministry – Chemical Enterprise Dudesti, Bucharest

The matrix representations of the microtectonic structures are well known. On their basis the author proposes a statistical-information processing methodology which is to reflect the homogeneity grade of the respective structures, utilising classical indicators and the hyperbolic information indicator.
Key words: tectonics, matrix statistics, information energy, information entropy, hyperbolic information.

MIXED PROBABILITY EQUATIONS AND INFORMATION ENTROPY
APPLICATION: VERTICAL INFILTRATION OF CANAL WATER

D. BERSADSCHI
Chem. Ind. Ministry – Chemical Enterprise Dudesti, Bucharest

Considering the known relation which denotes the vertical infiltration of canal water through the permeable layer of ground until reaching the underground water, one observes that it could be assigned a probability and informatical interpretation in the form of mixed equation.
Key words: technical geology, hydrotecnical construction, canals, infiltration, probability, information entropy, functional mixed equation.

INTERACTION EFFECTS IN MARINE SEISMIC SOURCE ARRAYS

V. VARODIN, AL. POPESCU, ST. COLBAN, M. TRIMBITASU, M. MARIN
Enterprise of Geological and Geophysical Surveys, Bucharest

The air-gun array technique involves the damping of the bubble pulses which are produced by an array of different air guns by mutual interaction. The air gun array consists of 21 air guns with a total volume of 2722 operated at a pressure of 2000 psi. The far field signatures which the source array at a depth of 5 m and 10 m, respectively, were recorded at a depth of 80 m.
Key words: air gun, bubble, signature, near field, far field, deep penetration, resolution.

EXPERIMENTS FOR THE USE OF SEISMICAL PROSPECTING
IN THE DETECTION OF COAL-BEDS IN THE SOUTH-WEST
AREA OF BUCHAREST

V. VARODIN, ST. COLBAN, AL. IONESCU, I. ZIHAN, MARCELA COSTESCU,
ST. ALBU, S. MINEA, M. OPREA
Enterprise of Geological and Geophysical Surveys, Bucharest

In order to extend seismical prospecting to coal beds, we performed some experiments necessary to record the seismic reflection line. We present the geological conditions, the experiments and the results obtained.
Key words: seismical prospecting, reflection line, coal beds.

EXPERIMENTS TO OPTIMIZE WAVE GENERATION IN ZONES
WITH ROUGH TOPOGRAPHY FOR SOLVING GREAT DEPTH PROBLEMS

ST. COLBAN, E. DANANAU, D. RAFAILA, V. DUMITRESCU, D. NEGUT, M. MITROI
Enterprise of Geological and Geophysical Surveys, Bucharest

To solve great depth problems in areas with rough topography and complicated WZ, a good knowledge of the conditions producing the seismic waves is very important. We present different generation patterns and different amounts of dynamite in a hole with a comparison of the results. We choose such generation patterns as to optimize the results for deep targets.
Key words: wave generation, complicated WZ, generation patterns, deep targets.

DIRECT AND INDIRECT INTERPRETATION OF THE SEISMIC FACIES WITH
SPECIAL REFERENCE TO THE PLIOCENE SEQUENCE IN THE NORTH-EAST
OF THE PANNONIC BASIN AREA

ANGELA LUNGU, GEORGETA GHEORGHIU, V. BARDAN
Enterprise of Geological and Geophysical Surveys, Bucharest

We mapped two seismic facies units outlining the south-western progradation of the end of the Pannonian Basin. On the basis of the seismic facies maps and interpreted environments we predicted the possibilites of development of the reservoir rocks. The associated presence of certain reflection signature anomalies supports the possible existence of stratigraphically closed traps and of some closed traps in roll-over anticlines or associated with normal detachment faults.
Key words: seismic facies, oblique facies, sygmoidal facies, progradation, down-lap, undaform, clinoform, roll-over anticline.

SOME LINEAR SPACES AND OPERATORS
APPLIED IN THE SEISMIC PROCESSING

V. BURUIANA, C. CRISTESCU
Enterprise of Geological and Geophysical Surveys, Bucharest

The main idea of the paper is to present the whole seismic processing as a result of the composition of some linear operators. The operators utilised and their composition are described.
Key words: linear space, linear operator, composition of operators, seismic processing, stable operator, Z-transform, migration

ACOUSTIC LOG PROCESSING FOR SEISMIC PROSPECTING

M. BARBU
Enterprise of Geological and Geophysical Surveys, Bucharest

The problems related to depth sampling, integration and time sampling of the acoustic logs are analysed by a new method; the usual one could not be applied due to the non-linear relationship between depth and time domains. The necessary sampling interval in depth is obtained as a result of this analysis.
Key words: processing, acoustic log, sampling, aliasing, integration.

COMPLEX METHOD FOR THE INTERPRETATION OF THE 3-D INFORMATION
BY AUTOMATIC PROCESSING OF THE MULTIARRAY SEISMIC SPATIAL
SOUNDING RECORDINGS IN THE CRACAOANI-NEAMT AREA

M. BELLU, ST. ALBU, J. STEINBERG
Enterprise of Geological and Geophysical Surveys, Bucharest

The technology used was the Multiarray Seismic Spatial Sounding (MSSS) and the processing of the data was automatically performed by means of special programs. The novelty consists in the automatic correlation based on the criteria transposed in a computer program; this offers the possibility of increasing the density of the subsurface signal imaging.
Key words: tectonics, 3-D seismic prospecting, flysch, MSSS, processing, automatic correlation, computer program.

POROUS MEDIA IN SEISMIC PROSPECTING

M. CRISTEA
Enterprise of Geological and Geophysical Surveys, Bucharest

The paper is a review of the theory and experiments concerning the wave propagation in porous media. It is also points out the utility of these studies in seismic prospecting.
Key words: compressibility, density, frequency, permeability, porosity, velocity, viscosity.

RESULTS OF THE SLALOM LINE METHOD IN SOME TOPOGRAPHICALLY
AND GEOLOGICALLY COMPLICATED AREAS

AL. POPESCU, P. NASTASE, R. GASPAR, D. TOMA
Enterprise of Geological and Geophysical Surveys, Bucharest

The slalom line seismic method allows the processing of the data recorded along non-straight lines. On land, this approach permits the use of seismic traverses avoiding natural obstacles: mountains, marshes, forests. This new technique was implemented in our country in 1981 in the very complicated area between the Dambovita valley and the Buzau valley.
Key words: slalom line, traverse, scatterogram, median point, velocity analysis, band width.

PRESENT STATE OF RESOLUTION IN REFLECTION
SEISMIC PROSPECTING

V. CUCU
Enterprise of Geological and Geophysical Surveys, Bucharest

This paper deals with the state of the art in the solution of geological problems by taking into account: the time, the amplitude, the attributes of the reflected wave, etc. The main factors affecting the waveform and some possibilities to increase the resolution are also presented.
Key words: time, amplitude, wave attributes, increasing of resolution.

NEW ASPECTS OF SEISMIC DATA PROCESSING

N. MOLDOVEANU
Enterprise of Geological and Geophysical Surveys, Bucharest

The aim of this work is to present the state of the art in seismic data processing and its implications in seismic interpretation.
Key words: state of the art, seismic data processing, processing implications in interpretation.

CONSIDERATIONS UPON WAVE PROPAGATION
IN ANISOTROPIC MEDIA

L. CRACIUN
Enterprise of Geological and Geophysical Surveys, Bucharest

The lack of precision of isotropic earth models in explaining important parameters, such as travel time, has induced the mathematical research on elastic wave propagation in anisotropic media. This paper describes a model whereby medium properties are constant along two space directions (transversely isotropic medium).
Key words: stress, strain, stratified medium, transmission coefficient, reflection coefficient, transverse isotropy.

IInd SECTION
GEOPHYSICAL INVESTIGATIONS
FOR SOLID MINERAL SUBSTANCES

Chairman: Acad. SABBA STEFANESCU

EXPLORATIONS BY GAMMA-RAY SPECTROMETRY –
MATHEMATICAL METHODS OF DATA PROCESSING

A. LUNG, D. PAICU, GH. GRECEA, R. CONSTANTINESCU
Enterprise of Rare Metals, Bucharest

The results obtained by statistical pattern recognition processing methods applied to the results of the explorations with four channel gamma-ray analysers are presented.
Key words: gamma-ray spectrometry exploration statistical pattern recognition, data processing.

BOREHOLE LOGGING BY NATURAL GAMMA-RAY SPECTROMETRY

C. NICOLAU, D. PAICU
Enterprise of Rare Metals, Bucharest

The experiments for determining the stripping ratios coefficients, between Ra and Th measurement channels, on different geometry and composition models and the determination of the pattern of the investigated anomalies are presented.
Key words: natural gamma-ray, spectral logging on models and in the holes.

QUANTITATIVE APPRECIATIONS OF EXPERIMENTAL SPECTRUMS
OF SOME RADIOACTIVE MODELS

I. DRUICA-ZELETIN3, M. AL. ONCESCU2, A. LUNG1, V. GEORGESCU1,
R. CONSTANTINESCU1, V. MARIN3
1Enterprise of Rare Metals, Bucharest
2Institute of Nuclear Physics and Engineering, Bucharest, Magurele
3Institute of Civil Engineering, Bucharest

The paper presents quantitative appreciations of the energy spectrum of the gamma-ray flux measured on some models (point, line, ring) with different attenuation environments, models with natural radioactive materials sources.
Key words: gamma-ray spectrums, natural sources.

MAGNETOMETRY AND KAPPAMETRY APPLIED IN THE DANUBE DELTA
AND THE RAZELM LAKE; SOME METHODOLOGICAL
AND SEDIMENTOLOGICAL ASPECTS

S. RADAN1, S. RADAN1, M. RADAN1, N. MIHAILESCU1, O. ANGELESCU2
1Institute of Geology and Geophysics, Bucharest
2Institute of Nuclear Physics Engineering, Bucharest

Some methodological and sedimentological aspects regarding the profiles recorded with a shipboard proton magnetometer and a kappameter in the Danube Delta and the Razelm Lake are discussed.
The lab susceptibility data characterizing the bottom sediments in some channels and lakes of the Fortuna-Rosu area (the Danube Delta) are also commented upon.
Key words: lacustrine area, shipboard protonic magnetometer, kappameter, botom sediment, magnetic susceptibility, sedimentology.

ON THE SOURCES OF THE POTASSIUM ANOMALIES MAPPED
BY AIRBORNE GAMMA SPECTROMETRY IN THE SOMOVA AREA

VL. ROSCA, S. SCURTU, VENERA CODARCEA, FL. RADULESCU
Institute of Geology and Geophysics, Bucharest

Airborne gamma ray spectrometry revealed in the Somova area some potassium anomalies situated above loessoidal deposits. On ground gamma spectrometry and mineralogical studies indicated the mica concentrations as a source of the gamma ray anomalies. An eolian and run off mechanism is proposed as a possible explanation of the mica concentrations observed.
Key words: airborne gamma ray spectrometry, potassium, Dobrogea, Somova.

X-RAY FLUORESCENCE METHOD FOR QUANTITATIVE ANALYSIS
OF MANGANESE AND IRON IN ORES AND THEIR DRESSING PRODUCTS

M. DUICU
Institute of Geology and Geophysics, Bucharest

Several versions of the E.D.X.R.F. method are comparatively presented. The method is used to determine the Mn and Fe from the manganese ores and their dressing products. The determination errors are ± 0.2 – 0.8% Mn and ± 0.2 – 1.2% Fe for contents of 4 – 47% Mn and 7 – 50% Fe. A Romanian POXA – 6 portable analyser has been used. Primary data have been processed by computer and graphical means.
Key words: E.D.X.R.F., Mn, Fe, ores, dressing products.

INTERPRETING MODEL OF THE MARINE MAGNETIC ANOMALIES
EAST OF THE PALAZU MARE

C. S. SAVA1, D.K. HANNICH2
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest

Starting from the structural model of the Palazu Mare zone, a mathematical model was realized to explain the magnetic anomalies from the sea domain.
Key words: marine magnetic anomalies, the Palazu Mare zone.

PALEOMAGNETISM OF THE BAUXITES OF THE PADUREA CRAIULUI
MOUNTAINS AND ITS PALEOTECTONIC IMPLICATIONS

S. RADAN, S. RADAN, MARIA RADAN
Institute of Geology and Geophysics, Bucharest

The paleomagnetic parameters measured on a collection of Cretaceous bauxites suggests a clockwise rotation of the Padurea Craiului Massif (Apuseni Mountains, Romania); the data are in agreement with those characterizing the other mobile areas in Europe.
Key words: bauxite, remanent magnetisation, Paleomagnetic pole, Paleotectonics, mobile area, Cretaceous.

NEW TECHNIQUES FOR ANALYTICAL TRANSFORMATION
OF GEOPHYSICAL DATA

V. STEFLEA
Center for Earth Physics and Seismology, Bucharest – Magurele

New techniques for the analytical computation of downward continuation and of vertical and horizontal derivatives are developed in spectral and space domains.
By means of this techniques it is possible to save the computing time and to obtain a higher precision.
Examples of theoretical and real cases are presented.
Key words: potential fields, analytical transformations, derivatives, downward continuations.

MATHEMATICAL MODELLING POSSIBILITIES
OF RADIOACTIVE ORE GAMMA-RAY FIELDS

M. AL. ONCESCU1, R. CONSTANTINESCU2
1Institute of Physics and Nuclear Engineering, Bucharest – Magurele
2Enterprise of Rare Metals, Bucharest

The possibilities of the mathematical modelling by Monte Carlo methods of the gamma-ray energy spectrums obtained with different NaI(Tl) scintillators on sources of different shape and composition of the natural radioactive elements are presented.
Key words: mathematical modelling, gamma-ray spectrums, natural sources.

QUANTITATIVE EVALUATIONS CONCERNING FIELD
GAMMA-RAY SPECTROMETRY

M. SASARMAN
Enterprise of Rare Metals, Bucharest

The measurements, experiments, the methodology of field measurements and data processing are presented. The quantitative evaluation possibilities of the method applied are discussed.
Key words: gamma-ray exploration spectrometry, data processing.

AUTOMATIC PRINTING OF SUBSOL STRUCTURAL MAPS USING VALUES
OF NATURAL POTENTIAL FIELDS

S. JITIAN, F. NEKULA, ST. MAKSAY, D. MILCOVEANU
Institute of Under-Engineering Education, Hunedoara

The relationship between the values of gravity anomaly obtained from geophysical exploration and isobaths of geological structure showing a certain density contrast was established on Fourier transform and deconvolution. Computations and maps were performed by computer techniques.
Key words: gravity anomaly, isobaths, deconvolution, Fourier transform, density contrast.

CONSIDERATIONS ON THE EVOLUTION OF NEOGENE MAGMATIC
PHENOMENA IN THE CARACI – MAGURA TEBEI REGION

D. CONSTANTINESCU1, SIMONA BRADU2
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest

In this paper, we try to present the differentiation of the Neogene magmatic rocks on the basis of the results of the petrophysical measurements and the succession of the moments of their putting in place, by using the polarity periods of the geomagnetic field.
The evolution diagram is completed by an analysis of the successive tectonic stages and some brief metallogenetic considerations.
Key words: magnetic maps, magmatic phenomena, geochronology, paleomagnetism, tectonics metallogenesis.

QUANTITATIVE INTERPRETATION ALTERNATIVE OF
THE GRAVITY ANOMALY IN THE SOUTH-WESTERN AREA OF
THE HARGHITA MOUNTAINS USING STATISTICAL ANALYSIS

D. RUSU, VICTORIA RUSU
Institute of Geology and Geophysics, Bucharest

The paper is a practical application of the opportunities offered by the statistical analysis of the quantitative interpretation of a gravity anomaly. Using the technique of equivalent models, the optimal concordance between the results of the observation data processing and the effects corresponding to the models approximating the actual geological structure was pursued.
Key words: quantitative interpretation, gravity anomaly, statistical analysis, equivalent model, vertical gradient of gravity, second derivative, power spectrum.

ON THE SPATIAL SENSITIVITY CHARACTERISTIC IN MAGNETICS

M. ROTH
Enterprise of Geological and Geophysical Surveys, Bucharest

The characteristic of the spatial sensitivity is a graphical representation of the weights contributed by various subsurface zones to the mean value of the studied quantity. The cases of the gravity and especially of the electric measurements were investigated by Stefanescu (1976). The aim of the present paper is to study this problem with a proton magnetometer and a vertical gradiometer.
Key words: spatial sensitivity characteristics, magnetics, weighted mean value, proton magnetometer, vertical gradiometer, monopole, dipole.

INFLUENCE OF METALLIC PIPE LINES ON INDUCED-POLARIZATION
MEASUREMENTS

M. SIMIONESCU, M. ROMAN, C. LAZAR
Enterprise of Geological and Geophysical Surveys, Bucharest

The paper describes the way the buried metallic pipe lines act on the resistivity and the I.P. parameter measured by different methods.
Key words: electrical resistivity, induced polarization.

MODEL OF CERDAC GRAVITY BODY

C. URSOIU, LIGIA ATANASIU
Enterprise of Geological and Geophysical Surveys, Bucharest

Three sections through the Cerdac salt lenses are obtained by using gravity and drilling data.
Key words: gravity, modelling gravity anomaly.

INTERPRETATION OF GRAVITY AND MAGNETIC DATA
FROM THE IULIA – NICOLA BALCESCU ZONE (NORTH DOBROGEA)

GH. MAXIM, I. CORNEANU
Enterprise of Geological and Geophysical Surveys, Bucharest

Information concerning the buried geological structure of North Dobrogea zone (Meidanchioi-Iulia fault and dl. Tatarului basic intrusive bodies) is presented.
Key words: gravity and magnetic interpretation, North Dobrogea geology.

UTILIZATION OF SLOW FIELD VARIATIONS CAUSED BY D.C. ELECTRICAL
RAILWAYS IN GEOELECTRICAL PROSPECTING

I. STOICA
Enterprise of Geological and Geophysical Surveys, Bucharest

Some of the principal questions concerning slow variations of the electrical field due to mining DC electrical railways and a method for using these variations in geoelectrial prospecting are analysed by models and experimental field measurements. The field measurements carried out in the Ostra zone (Eastern Carpathians) are compared with the resistivity and IP data.
Key words: geoelectrical prospecting, Ostra zone (Eastern Carpathians) geology.

ON LOCATING MASS CENTER BY SURFACE INTEGRALS OF GRAVITY DATA

M. IVAN
Enterprise of Geological and Geophysical Surveys, Bucharest

A general convergent formula for the first order momenta of the gravity field is presented, thus allowing to find the horizontal coordinates of the mass center. The vertical center can be found by means of the second order moment of the vertical gradient. Both 3-dimensional and 2-dimensional cases are analysed and practical formulae are proposed.
Key words: gravity, surface integration, gravity momenta, mass center, vertical gradient of gravity.

FOURIER TRANSFORM OF GRAVITY AND MAGNETIC FIELDS
OF A STRAIGHT VERTICAL BODY

M. IVAN
Enterprise of Geological and Geophysical Surveys, Bucharest

The case of an anomalous body having a particular form and distribution of density (magnetic susceptibility) is treated. The filtering of the observed gravity and magnetic data permits finding the horizontal distribution of density (magnetic susceptibility) and the shape of the cross-section of the body.
Key words: gravity, magnetic field, Fourier transform, filtering.

ON FIRST ORDER MOMENTA OF MAGNETIC FIELD COMPONENTS

M. IVAN
Enterprise of Geological and Geophysical Surveys, Bucharest

General convergent formulae of the first order momenta of magnetic field components (X, Y and Z) are presented. Both 3-dimensional and 2-dimensional cases are analysed. A practical formula for finding the mean magnetic susceptibility of the anomalous body from ?T data is obtained.
Key words: magnetics, surface integration, magnetic momenta, magnetic susceptibility.

ON LOCATING THE MAGNETIC CENTER BY SURFACE INTEGRALS
OF MAGNETIC DATA

M. IVAN
Enterprise of Geological and Geophysical Surveys, Bucharest

General convergent formulae for the second order momenta of magnetic field components are presented for both 3-dimensional and 2-dimensional cases. A magnetic center can be defined in the case of induced magnetization and its coordinates found. Practical formulae are given.
Key words: magnetic center, surface integration, magnetic momenta, magnetic center.

DISSEMINATED MAGNETITE AND COMPACT MAGNETITE
AS A SOURCE OF MAGNETIC ANOMALIES

D. ROMANESCU
Institute of Geology and Geophysics, Bucharest

The comparative study of the magnetic anomaly sources consisting of rocks containing disseminated magnetic or compact magnetite bodies, as well as of the respective anomalies led to the conclusion that the anomaly amplitude depends on the amount of magnetic in the volume unit.
Key words: magnetometry, petrophysics, magnetic susceptibility, andesite, banatite, disseminated magnette, pyrometasomatic.

GEOPHYSICAL REMARKS ON THE STRUCTURE
OF THE TIBLES MASSIF. FIRST PART. THE STUDY
OF SOME PETROPHYSICAL PARAMETERS

J. ANDREI1, ELVIRA CIUCUR1, N. DUMA1, O. EDELSTEIN2, C. NEDELCU-ION1,
T. NESTIANU1, ELENA SZABO1
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest

The study of the distribution of the bulk density and of the main petromagnetic parameters constituted an adequate background for the interpretation of gravity and magnetic anomalies. Thus it is worth noting the role of pyrrhotite dissemination of some magmatic and contact-metamorphic rocks in determining some important normal and reverse magnetic anomalies.
Key words: petrophysical parameters, Tibles Massif, interpretation of geophysical anomalies.

PETROPHYSICAL MAPS IN THE GILAU MOUNTAINS AREA

D. ROMANESCU, ELENA SZABO, V. STOENESCU, ANCA GEORGESCU
Institute of Geology and Geophysics, Bucharest

The petrophysical maps of density and magnetic susceptibility at surface and at a level of about –400 m in the Gilau Mountains area are presented. The maps at surface have been drawn on the basis of "in situ" and laboratory measurements and the deep level maps by using drilling data correlated with the information obtained from magnetic measurements.
Key words: petrophysical maps, magnetic susceptibility, density, eruptive rocks, sedimentary rocks, metamorphic rocks, the Gilau Mountains.

USE OF THE MAGNETIC SUSCEPTIBILITY ANISOTROPY
TO EXPLAIN THE STRUCTURAL PECULIARITIES OF THE NEOGENE
VOLCANISM IN THE CALIMANI-GURGHIU CHAIN

ANCA GEORGESCU1, T. NESTIANU1, D. ROMANESCU1, TATIANA SARCHIZOV2
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest

An attempt at explaining the structural peculiarities of the volcanic rocks in the Calimani-Gurghiu mountains using some characteristics of the main magnetic susceptibility spatial distribution is made. Some results concerning typical geological structures are presented.
Key words: Neogene eruptive, magnetic susceptibility anisotropy, main direction, the Calimani-Gurghiu chain.

CONTRIBUTIONS TO THE APPLICATION OF THE PALEOMAGNETIC
METHOD TO THE PLIOCENE AND QUATERNARY
MAGNETOSTRATIGRAPHIC INVESTIGATION OF THE BRASOV DEPRESSION

S. RADAN, C. GHENEA, M. RADAN, T. BRANDABUR, N. MIHAILA, GH. IONESCU
Institute of Geology and Geophysics, Bucharest

The paleomagnetic study of some Pliocene and Quaternary sections of the Brasov Depression (Romania) has led to the obtainment of some scales with normal and reversed magnetic polarities. These data have been used for the correlation of Plio-Pleistocene sequences contributing to a better defining of the stratigraphic image of the area under discussion.
Key words: remanent magnetisation, normal magnetic polarity, reversed magnetic polarity, Kaena event, Jaramillo event, Plio-Pleisticene section, magnetostratigraphical correlation.

GRAVIMETRIC AND MAGNETIC MARINE RESEARCHES
IN THE NEIGHBOURHOOD OF THE PALAZU MARE ZONE
ON THE BLACK SEA SHELF

C. S. SAVA
Institute of Geology and Geophysics, Bucharest

The paper presents the results of the researches carried out in 1980 and 1981. The gravity map shows the continuation of the Capidava-Ovidiu fault into the sea domain. The magnetic map reveals new anomalies, very interesting for clearing up the way in which the Palazu Mare structure continues eastwards.
Key words: gravimetric and magnetic marine researches, the Black Sea shelf, the Capidava-Ovidiu fault, the Palazu Mare structure.

CONTRIBUTIONS TO THE METHOD OF TRANSMITTED WAVES

P. CONSTANTINESCU, P. CRISTEA, GH. IONESCU
Enterprise of Geological and Geophysical Surveys, Bucharest

Some aspects concerning the method of transmitted waves applied for the investigation of the underground inhomogeneities are discussed. A few possibilities of improving this method are analyzed. Models with specific physical-geometrical characteristics are presented and some processing methods are commented upon.
Key words: seismic prospecting, transmitted waves, modelling in seismic, processing methods, program design.

MAGNETIC POLARITY OF THE LOESSES AND PALEOSOILS OF SOUTH
DOBRUDJA AND ITS CHRONOSTRATIGRAPHIC SIGNIFICANCE

S. RADAN, C. GHENEA, M. RADAN, A. GHENEA
Institute of Geology and Geophysics, Bucharest

Four sections in the South Dobrudja (Romania) consisting of an alternation of loess and paleosoil formations have been paleomagnetically investigated. The magnetic polarity suggests the chronostratigraphical positioning of these sequences in the Middle and Upper Pleistocene.
Key words: remanent magnetisation, magnetic polarity, loess, paleosoil, Middle Pleistocene, Upper Pleistocene, lithic tools.

MAGNETOMETRIC AND GAMMA RAY SPECTROMETRIC STUDY OF SOME
HYDROMETAMORPHIC HALOS IN THE METALIFERI MOUNTAINS

D. IOANE, J. ANDREI
Institute of Geology and Geophysics, Bucharest

The argilization-silicification hydrothermal processes affecting the igneous rocks of the Metaliferi Mountains induced the substitution of the accessory magnetite with iron sulphides and sometimes, an enrichment of the rocks in potassium minerals as well. These transformations are susceptible of a good application of magnetometry and gamma ray spectrometry in the hydrothermal halos study.
Key words: magnetometry, gamma ray spectrometry, hydrothermal halos study.

USING GEOELECTRICAL METHODS FOR SOLVING SOME
HYDROGEOLOGICAL PROBLEMS IN THE EASTERN CARPATHIANS

G. ZAMFIROIU1, C. LAZAR2
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest

The areas investigated correspond to different geological conditions. The main hydrogeological elements were watered faults. They were well shown by means of geoelectrical methods (resistivity and self potential). In many cases the authors also used successfully measurements of the underground carbon dioxide.
Key words: hydrological problems, geoelectrical methods, the Eastern Carpathians.

IIIrd SECTION
EARTH PHYSICS AND GEODESY RESERACHES

Chairman: prof. LIVIU CONSTANTINESCU, corresponding member of the Academy

STUDY OF RECENT CRUSTAL MOVEMENTS BY GEODETIC METHODS
IN THE GRUIU CALDARUSANI GEODYNAMIC POLYGON.
PRELIMINARY RESULTS

I. CORNEA1, D. GHITAU2, M. N. POPESCU1, C. SAVULESCU2, F. RADULESCU1,
A. ILIES2, D. ZUGRAVESCU1, A. FRESCHIN
1 Centre for Earth Physics and Seismology, Bucharest, Magurele
2 Institute of Civil Engineering, Bucharest

The paper presents the methods and geodetic instruments used, the algorithms for the computation of repeated, high accuracy measurements and a preliminary geodynamic interpretation of the results.
Key words: geodynamic polygon, geodetic repeated measurements, recent crustal movements.

SEISMOTECTONIC DEFORMATION IN EASTERN ROMANIA INFERRED
FROM SEISMIC MOMENTS AND FAULT PLANE SOLUTIONS

C. RADU, M. C. ONCESCU
Centre for Earth Physics and Seismology, Bucharest, Magurele

Using computer determined fault plane solutions of 86 intermediate Vrancea earthquakes (1929 – 1981), the temporal variation of the local mechanism was analysed. Three types of focal mechanism were evidenced and the seismotectonic deformation velocity tensors were computed. The analysis was also applied to 18 shallow events, two types of focal mechanism being determined.
Key words: focal mechanism, earthquake prediction, seismotectonic deformations velocity tensor.

SEARCH FOR PRECURSORY FLUCTUATIONS OF SOME SPECTRAL
PARAMETERS OF VRANCEA SEISMICITY

V. I. MARZA, M. C. ONCESCU
Centre for Earth Physics and Seismology, Bucharest, Magurele

The spatio-temporal variations of some spectral parameters (corner frequency, low-frequency level, slope of high-frequency segment etc.) of Vrancea seismicity were investigated with the aim of detecting precursory variations.
Key words: earthquake prediction, precursory seismicity, spectral parameters, Vrancea region.

ON SOME PRECURSORS OF INTERMEDIATE DEPTH EARTHQUAKES
IN THE VRANCEA REGION, ROMANIA

GR. ARSENE1, V.I. MARZA2, A. APOSTOL2
1Department of Mathematics, INCREST, Bucharest, Romania
2Centre for Earth Physics and Seismology, Bucharest, Magurele

After presenting a hypothesis about the source of the intermediate depth earthquakes in the Vrancea region, some of their precursors such as a precursory seismicity, time variations of tectonic stress directions and parameters deduced from a systemic model for controlling the error in Wienerian prediction are studied.
Key words: the Vrancea region, intermediate earthquakes, precursory seismicity, geophysical precursors, dowsing reaction, tectonical stress, Wienerian prediction.

DEEP STRUCTURE IN THE VRANCEA REGION INFERRED FROM
SIMULTANEOUS HYPOCENTER AND THREE-DIMENSIONAL VELOCITY
INVERSION

M. C. ONCESCU
Centre for Earth Physics and Seismology, Bucharest, Magurele

An efficient multi-iterative, algorithm for simultaneous hypocenter and 3-D velocity inversion was developed and applied to a set of arrival times in 119 local events recorded at least by 6 stations of the telemetered seismic network. On the basis of final locations and velocities, which yield a 80% reduction in residual variance, a tectonic model for the Vrancea region was proposed.
Key words: 3-D velocity structure, arrival time inversion, Vrancea.

STATISTICAL MODELLING OF THE LARGEST VRANCEA EARTHQUAKE
OCCURRENCE

A. PANTEA, D. JIANU, V. MARZA
Centre for Earth Physics and Seismology, Bucharest, Magurele

The theory of extreme values is applied to earthquake instrumental records of the Vrancea seismogenic region for a time span of half a century. The model supplies parameters of seismic hazard as: probabilities of occurrence, return periods, largest magnitude, etc. which ere compared with former results.
Key words: earthquake statistics, theory of extreme values, seismic hazard, upper magnitude, the Vrancea region.

ACTIVE FAULTS IN ROMANIA IN THE PERIOD
MARCH 4, 1977 – JANUARY 1, 1982

M. ANGHEL, V. SMALBERGHER
Centre for Earth Physics and Seismology, Bucharest, Magurele

A number of about 600 shallow earthquakes (h 50 km, standard deviation 2.0) were located and used for epicentral maps computer plotting (scale 1 : 1,000,000). By superposing of these maps on the tectonic and neotectonic maps, the seismic active faults were emphasized for period March 4, 1977 – January 1, 1982.
Key words: Romania's seismicity, active faults, earthquake location.

SYNTHETIC ACCELEROGRAMS FOR AN ANTIPLANE RUPTURE
ON A VERTICAL FAULT

C. I. TRIFU, M. RADULIAN
Centre for Earth Physics and Seismology, Bucharest, Magurele

The near field motion for a dynamic model of antiplane rupture was determined by the finite difference method. The stress drop and the instant rupture front velocity were considered as known. The faulting models of constant velocity, interrupted rupture, and variable velocity were studied. The results clearly reflect the physical process within the focus.
Key words: synthetic accelerogram, near field motion, antiplane rupture.

GEODETIC ASTRONOMY AND SPACE GEODESY IN SOLVING
SOME PROBLEMS RELATED TO OUR PLANET

AL DINESCU
Institute of Fotogrametry, Geodesy, Cartography and Territory Organization, Bucharest

Future concerns within geodetic astronomy and space geodesy are presented. The results obtained by Doppler observations which were used in the point network establishment (at 200 – 300 km) or in the pole movement study are dwelled upon. The very accurate and completely automatized Doppler measurements can replace Laplace azimuths in the future. The usefulness of Doppler satellite-to-satellite observation in increasing the measurement accuracy is shown.
Key words: Doppler observatory, Laplace azimuths, satellite-to-satellite observations.

COMBINED METHODS USES IN SPACE GEODESY

H. ALEXANDRESCU
Institute of Fotogrametry, Geodesy, Cartography and Territory Organization, Bucharest

Combined methods consist in simultaneously solving equation systems yielded by geometric, orbital and dynamic methods, as well as by aerial surveys. The results obtained are used to establish terrestrial harmonic coefficients and station coordinates, the Earth's shape respectively.
Key words: space geodesy, aerial surveys, Earth's shape, tesseral harmonic coefficients, geometric, orbital and dynamic methods.

THE EARTH'S FORM AND SIZES – THE GEODESISTS' SPHERE OF ACTION

M ROTARU
Military Topographic Direction, Bucharest

In the paper some retrospective remarks are made in the main, with concrete reference to this field; they enable a survey and a general view of the development of geodesy.
A few examples are given which present the recent essential changes as well as some prospective orientations.
Key words: Earth's shape and size, development of geodesy.

SOME CONSIDERATIONS ABOUT THE GEODETIC DATUM

G. MARTON
Military Topographic Direction, Bucharest

The correct evaluation, combination and processing of terrestrial and satellite geodesy, time dissemination and precision gravimetry measurement data require the establishment of reliable and high precision references frames.
Some aspects regarding the choice of reference systems, with emphasis on the ones concerning the geodetic datum needed in the national networks processing are presented in the paper.
Key words: geodetic datum, satellite geodesy, reference frames, national networks processing.

ON SOME RECENT ASPECTS CONCERNING THE ADJUSTMENTS
OF GEODETIC AND GRAVIMETRIC NETS

G. TRAISTARU
Military Topographic Direction, Bucharest

Some aspects concerning the mathematical model of free adjustments are studied, as well as the conditions for avoiding the singularity of the normal equation system matrices.
Some alternatives of problem solution for unidimensional and bidimensional nets are shown too.
Key words: free adjustments, normal equation system matrices, unidimensional and bidimensional nets.

ELECTRONIC REMOTE CONTROL TRANSDUCER UNITE
FOR QUATZ STRAINMETER (ECTS)
(Poster)

R. DOROBANTU1, DOREL ZUGRAVESCU1, M. BONATZ2, N. PUSCASU3
1Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest,
2Institut für Theoretische Geodäsie, Bonn Universität, West Germany
3University of Bucharest, Bucharest

The recordings accomplished by an experimental strainmeter tested in the Laboratory of calibration and ageing of the geodynamical apparatus are presented. Its operation under known conditions (known amplitude and shape displacements) ensures that ECTS can be used in the underground geodynamic observatories, owing to its characteristics (sensitivity, fidelity, thermal drift, reliability).
Key words: geodynamcis, geodynamic observatory, crust deformations, Earth tides, strainmetry.

PROGRAMMABLE SYSTEM FOR THE DZ-TYPE HORIZONTAL PENDULUM
CALIBRATION (SHPC)
(Poster)

DOREL ZUGRAVESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The DZ-type horizontal pendulum calibration in the Craciunesti-Deva and Pades-Gorj observatories are presented as carried out by SHPC, a system built up of devices of our own conception: the device producing a sinusoidal pressure variation and the mercury deforming capsule (see "Exhibition").
Key words: geodynamics, underground observatory, crust deformations, Earth tides, tiltmetry, calibration system.

DEFORMING CAPSULE USED FOR THE DZ-TYPE HORIZONAL PENDULUM
CALIBRATION AND ITS INTERFEROMETRICAL CALIBRATION
(Poster)

DOREL ZUGRAVESCU, R. DOROBANTU, ILEANA FATULESCU, D. DELION
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The deforming capsule, a device allowing to carry out relative, reproductible displacements of the nm order, is calibrated in the Laboratory of calibration and ageing of the geodynamical apparatus, using an interferometrical device in order to establish de absolute value of its deformation corresponding to a known inner pressure variation in the range of 0 – 4 at. Repeated calibrations pointed out the elastic characteristics of the capsules realized (variations of 0.5% year).
Key words: geodynamics, geodynamic observatory, Earth tides, crust deformations, tiltmetry, strainmetry, interferometry.

ON-LINE SYSTEM FOR THE FILTERING AND STORING OF
THE GRAVIMETRIC TIDE RECORDINGS (SSGT)
(Poster)

R. DOROBANTU, DOREL ZUGRAVESCU, D. HARTIA, D. DELION Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

SSGT built by coupling our device for the filtering and storing control of the geodynamical data (see "Exhibition") with a digital clock and a paper tape puncher allowed the digital recording of the information furnished by the BN – 14 gravimeter of the Caldarusani Geodynamic Observatory (within the interval October 1981 – October 1982). This way the errors caused by the hand-made digitization were completely removed and a direct interfacing with the processing computer was accomplished.
Key words: geodynamics, underground observatory, Earth tides, geodynamic apparatus, data storage.

LARGE SCALE, STABLIZED RATE OPTICAL RECORDER – A COMPONENT
OF THE CLINOMETRIC SYSTEM CONTAINING
THE HORIZONTAL PENDULUM (SSOR)
(Poster)

DOREL ZUGRAVESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The experimental recordings obtained by a clinometric system built up from a DZ-type horizontal quartz pendulum and an opto-electronical recorder (see "Exhibition") are presented. The time scale stability, the absence of operator produced perturbations as well as the accurate determination of self-period of the horizontal pendulum are emphasized.
Key words: geodynamics, underground observatory, crust deformations, Earth tides, tiltmetry.

DEP STRUCTURE OF THE REGION BETWEEN THE MOTRU VALLEY
AND THE ARGES VALLEY AS REFLECTED
IN GEOPHYSICAL RESEARCH RESULTS

M. VISARION, D. STANICA, M. STANICA
Institute of Geology and Geophysics, Bucharest

The correlation of the gravity, magnetic and seismic data with recent results supplied by magnetotelluric research in the region between the Motru Valley and the Arges Valley provides new information about the main discontinuities of the crust and particularly about the depth of the sedimentary deposits which exceeds 12 km in the down-throw zone of the basement.
Key words: electromagnetic field, magnetotelluric soundings curve, impedance, impedance tensor, conductance, high conductivity layer, electric contrast limits.

CORRELATION PALEOTECTONICS – RECENT MOVEMENTS
IN THE EASTERN CARPATHIANS ARC BEND

V. LAZARESCU1, M. N. POPESCU2
1Faculty of Geology and Geography, Bucharest University, Bucharest
2Centre for Earth Physics and Seismology, Bucharest – Magurele

In the present paper the tendencies of cumulative offsets disclosed by faults and of sigmoidal curves displayed by the fold axes in the Eastern Carpathians Arc Bend are analysed.
This information is used in the region for interpretation of possibilities of deep movements in terms of plate tectonics.
Key words: internal geodynamcis, structural geology, recent crustal movements, plate tectonics.

HOMOMORPHIC PROCESSING OF LANDSAT IMAGE RECORDINGS

M. ATANASIU, V. BARDAN
Enerprise of Geological and Geophysical Surveys, Bucharest

This paper presents the results of the homomorphic filtering applied to LANDSAT satellite data recordings. The processing was performed by means of a digital computer and the B/W and color results were displayed by means of a digital laser plotter.
Key words: LANDSAT images, digital homomorphic filtering, color display, B/W display.

THREE-DIMENSIONAL VELOCITY IMAGE UNDER THE CARPATHIAN ARC

M. C. ONCESCU, V. BURLACU, M. ANGHEL, V. SMALBERGHER
Centre for Earth Physics and Seismology, Bucharest – Magurele

Using the ACH method, the P-wave velocity anomalies in a three-dimensional block structure under the Romanian seismic network were determined. The gravity anomaly computed by this model is in a remarkably good agreement with the observations. The
P-wave velocity perturbations on the chosen scale support the tectonic model for the Vrancea region proposed by Fuchs et al. (1979).
Key words: 3-D velocity structure, arrival time inversion, Vrancea.

PROBLEMS CONCERNING GEOLOGICAL HAZARD EVALUATION

N. MANDRESCU
Centre for Earth Physics and Seismology, Bucharest – Magurele

The so-called side effects, normally associated to strong earthquakes, have often generated much more damage than the seismic vibrations themselves.
The paper points out the importance of identification, delimitation and characterization of regions susceptible of permanent deformations during earthquakes in order to avoid or mitigate the earthquake damages.
Key words: natural phenomena, strong earthquakes, geological processes, landslide, liquefaction.

IMAGES AND GEOLOGICAL SIGNIFICANCE OF THE TEMPERATURE
AND GEOTHERMAL GRAIDENT DISTRIBUTION
IN WALACHIA AND OLTENIA

A. NEGUT
Faculty of Geology and Geography, Bucharest University, Bucharest

The primary and derived maps of temperature and average geothermal gradient distribution in the Moesian Platform and the Carpathian Foredeep from Walachia and Oltenia are presented. Some of their geological significances are discussed.
Key words: temperature, geothermal gradient, geothermal maps, geological significance.

CHARACTERISTICS OF THE SECULAR VARIATION AND OF THE NORMAL
DISTRIBUTION OF THE GEOMAGNETIC FIELD IN ROMANIA

C. DEMETRESCU1, M. ENE1, T. NESTIANU2
1Centre for Earth Physics and Seismology, Bucharest – Magurele
2Institute of Geology and Geophysics, Bucharest

The results of the geomagnetic measurements taken during the last ten years in a network of about 30 stations in Romania are presented. The main characteristics of the geographical distribution of the secular variation (isopore and smoothed isopore maps for various quasiconstant S.V. intervals) and of the normal field are rendered evident.
Key words: geomagnetism, secular variation, normal field, isopores, S. V. Impulse.

MYCROSYSTEM FOR THE ON-LINE ACQUISITION AND PROCESSING
OF THE GEODYNAMIC DATA (APM)
(Poster)

R. DOROBANTU, V. GHEMIGIAN, D. DELION, DOREL ZUGRAVESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The APM secures directly or by remote control (telephonic Modem) the storage of the data collected by the geodynamic sensors, by coupling a central unit (MPU – 8080) with the peripherals for the geodynamic data storage (magnetic tape unit, paper tape puncher), with a graphic display (digital printer, plotter), with the input devices of the graphically stored data (digitizer), the time marking of the sampling being realized on-line (GMT).
Key words: geodynamics, Earth tide, geodynamic apparatus, geodynamic observatory data acquisition, data processing, data storage.

RADIOGENIC HEAT GENERATION IN THE CARPATHIAN AREA

S. VELICU, M. LEMNE, O. ROMANESCU, I. TIPEAC
Institute of Geology and Geophysics, Bucharest

Using the results of the spectrometric measurements on rock samples, the radiogenic heat generation within the upper layer of the crust has been evaluated. Accordingly, some thermotectonic events are discussed.
Key words: heat generation, heat sources, tectonics of the Carpathians.

SOME CONSIDERATIONS ABOUT THE STRUCTURE OF THE BASALTIC
LAYER AND THE REGIONAL ANOMALY OF THE GEOMAGNETIC FIELD
IN THE ROMANIAN TERRITORY

L. BESUTIU
Institute of Geology and Geophysics

The integrated interpretation of geophysical data has permitted to establish an interesting relation between the structure of the basaltic layer and the regional anomaly of the geomagnetic field. An original criterion for the deep crustal faults detection is also suggested.
Key words: basaltic layer, regional anomaly, geomagnetic field, deep faults detection.

CONTRIBUTION TO THE EARTH'S CRUST AND UPPER MANTLE STUDY
BY MAGNETOTELLURIC SOUNDINGS IN ROMANIA

D. STANICA, M. STANICA
Institute of Geology and Geophysics, Bucharest

Presented like a synthesis of the last 4 years M. T. investigations, this paper makes an important theoretical and experimental contributions to the earth's crust and upper mantle geoelectric investigation. The M. T. S. curves for two possible instances, E-polarized and H-polarized, as well as S = f(h), are a telling argument.
Key words: magnetotelluric sounding curves, impedance tensor, conductance, high conductivity layer, anisotropy ellipses, electric contrast limits.

ACOUSTIC EMISSION AND ROCK DILATANCY

N. CRISTESCU
University of Bucharest, Faculty of Mathematics, Bucharest

The paper presents the experimental results and a mathematical model able to describe the creep of the rocks and its connection with the acoustic emission. It is shown that the threshold of dilatancy coincides with a sudden increase of the acoustic emission frequency. A relationship between the stationary and tertiary creep and the acoustic emission is established.
Key words: rock creep, acoustic emission, dilatancy.

USE OF HEAT SOURCE PATTERNS IN SOLVING
THE GEOTHERMAL FIELD

H. ACKER, GEORGETA ACKER
Industrial Secondary School – Oil and Gas Profile, Pitesti

The pattern allows first of all the determining of temperature for the layers of the lithosphere at the level of the whole globe. One takes into account the variation of thermal conductivity with temperature, and that of convection and radioactive disintegration in rocks. Finally, by integrating limit strata in Poisson's equation for thermal conductivity, one obtains the field temperature in any of their points.
Key words: head source, thermal energy, earth's revolution, thermal energy losses, thermal resistance, lithosphere, thermal gradients, salt deposits.

ABOUT THE TIDAL TRIGGERING OF THE VRANCEA EARTHQUAKES

DOREL ZUGRAVESCU, ILEANA FATULESCU, D. DELION, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The 1550 Vrancea earthquakes recorded within the interval 1 April 1977 – 1 April 1981 by the seismic network of CFPS have been studied. It is shown that more than 50% of the 1218 earthquakes with M < 3 and about 45% of the 332 earthquakes with M 3 were produced near the tide extreme. This result allows to consider that for the Vrancea earthquakes the Earth tides have a triggering effect.
Key words: geodynamics, Earth tide, earthquakes, triggering effect, Vrancea region.

EARTH TIDE DATA ANALYSIS USING FREQUENCY POLYNOMIAL
FUNCTIONS (DAFPF)

D. DELION, DOREL ZUGRAVESCU, ILEANA FATULESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Assuming a parabolic-type dependance of the main characteristics of the Earth tides (MCED), the DAFPF removes the very large errors which affect the MCET classically determined and considerably reduces the computation time. The method cannot be applied when the information concerning local peculiarities which affect certain frequencies is interesting for study (resonance, for instance).
Key words: geodynamic, Earth tides, analysis methods, polynomial function, angular frequency.

MAIN CHARACTERISTICS OF THE EARTH TIDE (MCET)
AT THE CALDARUSANI GEODYNAMIC OBSERVATORY – 1981

DOREL ZUGRAVESCU, D. DELION, ILEANA FATULESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The MCET by Venedikov, Chojnicky and DAFP methods, from the gravimetric tide recordings, have been determined. The MCET values determined for several time intervals and then for a whole year are less affected by aleatory variations than those determined by Chojnicky and Venedikov methods.
Key words: geodynamics, Earth tides, analysis methods, polynomial function, angular frequency, Caldarusani.

MODEL IN SUPERPOSED LAYERS AND INTERNAL RADIOACTIVE HEAT
SPRINGS FOR INTERPRETING THE THERMAL WAVE OF THE EARTH

D. MILCOVEANU
Institute of Under-Engineering Education, Hunedoara

The character of the thermal conditions of the Earth is strongly influenced by the radioactive elements U, Th and K in the upper layers of the Earth which on their disintegration emit important quantities of heat. In this respect, a model which includes this phenomenon and explains in a more complete way the thermal wave of the Earth is presented.
Key words: thermal conditions of the Earth, radioactive elements, geothermal wave, geothermal model.

BLASTING SEISMOLOGY: AN OVERVIEW OF BASIC PROBLEMS AND
RECENT DEVELOPMENTS WITH APPLICATIONS TO ROMANIA

V. I. MARZA, A. PANTEA
Centre for Earth Physics and Seismology, Bucharest – Magurele

After an overall analysis of the generation of blast-induced vibrations and effects, instrumentation, damage criteria, blasting vibration control methods, and some empirical formulae for dynamical parameters assessment, the latest advances and recommendations are pointed out. Finally, several practical problems encountered in Romania are outlined.
Key words: blasting seismology, damage criteria, safe levels, dynamical parameters of vibration.

FREQUENCY ANALYSIS WITH MOVING TIME-WINDOW
OF SEISMIC REFRACITON DATA

A. BALA
Centre for Earth Physics and Seismology, Bucharest – Magurele

The application of the frequency analysis with the moving time-window method to some seismic refraction data with the object of emphasizing the frequency characteristics of different types of elastic waves is suggested. Some seismic records of the Sitormen-Turcoaia profile (Tulcea County) are analysed.
Key words: frequency analysis, moving window, seismic refraction data.

STUDY OF SEISMIC SOURCE FROM CODA WAVES
FOR LOCAL INTERMEDIATE EARTHQUAKES

VICTORIA OANCEA, OLIVIA BAZACLIU
Centre for Earth Physics and Seismology, Bucharest – Magurele

Coda characteristics of the Vrancea intermediate earthquakes are determined by short-period vertical digital recordings filtered in eight frequency bands for the Cheia station. By the coda analysis the Qs factor and its dependence on frequency, the coda source factor and the seismic moment-magnitude relation are determined.
Key words: coda, intermediate earthquake, Vrancea, Qs factor, seismic moment.

SEISMIC MOMET TENSOR INVERSION FROM SURFACE WAVES

C. I. TRIFU
Centre for Earth Physics and Seismology, Bucharest – Magurele

A group of programs was elaborated to evaluate the seismic moment by making use of surface wave trains. The observed seismograms were equalized for group and phase velocities determined for each train respectively. The theoretical seismograms were computed for a multilayered Earth, either flat (T 100 s), or spherical (T 100 s).
Key words: mechanism inversion, seismic moment tensor, surface waves.

WEIBULL STATISTICS OF THE VRANCEA INTERMEDIATE EARTHQUAKES

M. RADULIAN
Centre for Earth Physics and Seismology, Bucharest – Magurele

Weibull statistics was applied for several sets of Vrancea intermediate earthquakes. If the set consists of earthquakes with Ms of 4.0 the Poisson distribution is shown to be a good model for the occurrence time. When great earthquake sequences (M 6.4) are considered alone, a Weibull distribution fits better the available data. Differences of seismic hazard determination using these two statistics are emphasized.
Key words:: seismic hazard, Poisson distribution, Weibull distribution.

ANOMALOUS BLACK SEA LEVEL CHANGE BEFORE THE NOVEMBER 1981
TULCEA EARTHQUAKE

S. MANTU
Centre for Earth Physics and Seismology, Bucharest – Magurele

The analysis of Black Sea level data recorded by three tidal stations on the Romanian coast pointed out a short time precursor anomaly before the November 1981 Tulcea earthquake.
Key words: sea level, precursor anomaly, tidal station, earthquake.

PACKAGE OF PROGRAMS FOR AN ACQUISITION AND PRELIMINARY
PROCESSING SYSTEM OF THE GEODYNAMIC DATA (PAPGD)

D. DELION, R. DOROBANTU, DOREL ZUGRAVESCU, ILEANA FATULESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

PAPGD allows a variable step sampling (within the interval 10-4s – 104s), the storage of the information on a large-capacity support (magnetic tape, floppy disc) and its preliminary processing – numerical filtration, spectral correlation analysis – respectively curve digitization, graph drawing in a conversational system.
Key words: geodynamics, Earth tides, package programs, data acquisition, data processing, data stockage, magnetic support structure.

SEISMZON – QUAKEON MODEL

M. ANGHEL
Centre for Earth Physics and Seismology, Bucharest – Magurele

On the basis of some postulates (the main being the elementary-structured dualism) the model called "Seismzon-Quakeon" is developed for a better understanding of the organization of the matter structure at the tectonic plates level and for its application in earthquake prediction.
Key words: structure organization, Seismzon, Quakeon, fuzzy sets, prediction.

EXHIBITION AND POSTERS OF INSTRUMENTS IN THE FIELD
OF EARTH PHYSICS AND APPLIED GEOPHYSICS

SELF-CORRECTING DIGITAL CLOCK

D. VOICULESCU
Centre for Earth Physics and Seismology, Laboratory of Seismology, Bucharest – Magurele

The instrument is used to give time marks (minute and hour) to geophysical/ seismological recordings. The output is given by a contact (relay) closure. The clock has an internal radio receiver which permanently receives the Bucharest broadcasting station on 155 kHz. Time signals transmitted at 1 – 2 hours interval (6 pulses of 0.1 s, at 1 s interval, modulated by 1 kHz) are used automatically correct to zero any error. Accuracy is practically the accuracy of timing signals (les than 10 ms at any time).
Key words: geophysical/seismological instrument, automatic correction, time marks.

BATTERY CHARGER

D. VOICULESCU
Centre for Earth Physics and Seismology, Laboratory of Seismology, Bucharest – Magurele

The charger has an output voltage of 13.5 V and a current capability of 3 A. The current limit is adjustable between 1 and 3 A. It is primarily used in a floating mode, to charge batteries used with equipment which needs uninterrupted 12 VDC power.
Key words: geophysical instrument, floating charger.

TYPE MPP-78 PROTON MAGNETOMETER

O. ANGHELESCU
Institute of Physics and Nuclear Engineering, Bucharest – Magurele

Realized on the basis of the free nuclear precession principle the MPP-78 proton magnetometer is meant for determining the geomagnetic field both for magnetic mapping (geophysical, archeological prospecting etc.) and observatory activities (diurnal variation). The determinations do not involve calibration operations and do not depend on the transducer orientation; the instrument is provided with analogic and digital output.
Measuring range: 42,000 – 60,000 nT
Maximum admissible gradient of the field to be measured: 500 nT/m
Repetition period of the determinations: 9 s
Accuracy and resolving power: 1 nT
Conversion constant: 1 mV/nt
Analogic and digital output
Display with LED 5 digit photo-emissive diodes.
Key words: globe physics, geophysical instruments, geomagnetism, geomagnetical observatory, geophysical surveys, magnetometry.

OPTICAL RECORDING HORIZONTAL PENDULUM

DOREL ZUGRAVESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Made of quartz, and only of mechanical and optical components, the optical horizontal pendulum (Verbaandert – Melchior principle) points out locally, with a high precision, the variations of the relative position of the vertical against the surface of a pillar solidarity jointed with the crust and the air pressure fluctuations. After an adequate ageing of the suspension system, the device has a very good reliability and time stability (Fig. 1a; axiometric view – Fig. 1b).
Resolution: 5x10rad
Nonlinearity: < 1%
Fidelity: distortion factor < 1%.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformation, Earth tides, tiltmetry.

OPTO-ELECTRONICAL RECORDER

DOREL ZUGRAVESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Realized of Romanian made components, the device assures nine rigorous constant rates of the rewinding of the photosensitive paper, by a quartz oscillator piloted step by step motor. The passing from one rate to another is operated by remote control (Fig. 2a; axonometric view – Fig. 2b).
Winding rates: 0.00225 m/h; 0.00450 m/h; 0.00900 m/h; 0.0180 m/h;
0.0360 m/h; 0.072 m/h; 0.144 m/h; 0.288 m/h; 0.576 m/h;
1.152 m/h.
Paper hopper: 45 m
Supply voltage 10 – 18 V c.c.
Absorbed power: 12 VA
Pointed of the paper store
Quartz piloted: 60 kHz.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformation, Earth tides, tiltmetry.

OPTO-ELECTRICAL RECORDER

DOREL ZUGRAVESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Made of Romanian components, the opto-electrical recorder provides continuous recording within 45 days, without replacement of the photosensitive paper. The paper rewinds from a debitor drum on a collector drum, a presser roll assuring its correct position in the rear side of the slot. The displacement rate of the paper is constant if the supply of the electrical motor operating the clock mechanism is stable (Fig. 3a; axonometric view – Fig. 3b).
Winding rate: v1 = 0.006 m/h
v2 = 0.300 m/h
Paper hopper: 45 m
Supply voltage: 6 V
Absorbed power: 4 VA.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tides, tiltmetry.

MERCURY DEFORMING CAPSULE

DOREL ZUGRAVESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Consisting of Romanian made components, the mercury deforming capsule, an essential element of the calibration system of the horizontal pendulum, the quartz strainmeter and the displacement transducers, is made of a stainless steel disc, having its inner empty space connected by a flexible tube to the mercury vessel of the calibration system (the Verbaandert-Melchior principle) (Fig. 4a; axonometric view – Fig. 4b).
Time stability of the properties: very good (drift < 0.5%/year).
Remarkable reliabilty (no trouble in over ten years).
Sensitivity of the order of 10m/m (the capsule deformation/the displacement of the mercury vessel surface).
Key words: geodynamics, geophysical instrument, underground observatory, crust deformation, Earth tides, tiltmetry, strainmetry, interferometry.

POTENTIONETRIC RECORDING HORIZONTAL PENDULUM

DOREL ZUGRAVESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The device has been accomplished by replacing the quartz mass of a horizontal pendulum by a conductor plate placed in the adjustable air gap of two permanent magnets, the system allowing an optimal damping. A differential system of photoelectric cells with the potentiometric recording of their voltage was inserted in the path of the light spot reflected by the mirror of the mobile arm. The obtained data may be remotely recorded (Fig. 5a; axonometric view – Fig. 5b).
Resolution: 5x10rad
Nonlinearity: < 1%
Fidelity (distortion factor): < 1%.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tides.

SINUSOIDAL INVERTER (SI) 220 V/250 W

R. DOROBANTU1, DOREL ZUZGRAVESCU1, ST. FANACA2
1Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest
2Enterprise of Research Apparatus and Equipment, Bucharest

Meant for the autonomous 220 V a.c. supply of the apparatus placed in geodynamical observatories (tiltmeters, gravimeters, strainmeters, barographs, thermographs) but utilizable in other fields, too, exclusively made of Romanian components, SI is supplied from an accumulatory of 24 V c.c. and its output is protected against short circuit damage (Fig. 6).
U0 = 220 V a.c.
P0 max = 250 W
Stabilization factor of the output electrical voltage for the load changing
0.1 IM ÷ IM : 2x10
Stabilization factor for the input electrical voltage changing
Ui = 22 V – 28 V : 10
Distortion factor: < 5%
Zero load input current: < 2A
Maximum load input current: < 20 A.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tide, gravimetry, tiltmetry, strainmetry.

DEVICE PRODUCING A SINUSOIDAL VARIATION OF THE PRESSURE (DSVP)

DOREL ZUGRAVESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Consisting of Romanian made components (the Verbaandert-Melchior principle), DSVP accomplishes a sinusoidal variation of the pressure with a present amplitude and triggering. The device is composed of two independent parts, the first assuring the time preset and the second the turning, in a vertical plane, with a constant velocity, of the arm equipped with the mercury vessel connected by a flexible tube to the enclosure where the sinusoidal variation of pressure has to be induced (Fig. 7a; axonometric view – Fig. 7b).
Induced pressure: 0.15 – 0.50 at.
Period of the sinusoid: 0.25 – 2.5 h
Scheduled triggering: 1 – 7 days.
Distortion factor: < 1%.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tides, strainmetry.

BAROGRAPH WITH MANOMETRIC CAPSULE

DOREL ZUGRAVESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Realized of Romanian made components and destined to geodynamic observatories, the barograph has a battery of corrugated manometric capsules as the sensitive element. Its deformation acts an optical lever which furnishes the information potentiometrically recorded by a differential system of photocells (Fig. 8a; axonometric view – Fig. 8b).
Sensitivity: 10 V/bar
Great stability of its properties.
Key words: geodynamics, geophysical instrument, underground observatory, Earth tide, atmospheric pressure, crust deformations.

ZERO-METHOD PENDULUM

DOREL ZUGRAVESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Using a DZ-type horizontal quartz pendulum with magnetically damped oscillations as a transducer and a piezoelectric deforming capsule system to compensate the tilt, the device accomplished many run in a small space; it allows the remote recording of the data as well as the remote control of the transducer (Fig. 9a; axonometric view – Fig. 9b).
Resolution: 5x10rad
Nonlinearity: < 1%
Fidelity (distortion factor): < 1%.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformation, Earth tides, titltmetry.

PIEZOELECTRIC DEFORMING CAPSULE

DOREL ZUGRAVESCU, R. DOROBANTU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The piezoelectric deforming capsule, a device able to take over the main functions of the mercury deforming capsule, is composed of a ceramic piezoelectric disc placed in a stainless steel case (the Ruymbeke principle) (Fig. 10a; asonometric view – Fig. 10b).
Good reliability.
Sensitivity of the order of 0.35x10m/V (capsule deformation/applied voltage).
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tides, tiltmetry.

OPTO-MECHANICAL RECORDER

DOREL ZUGRAVESCU
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Realized of Romanian made components, the device consisting of a light spot projector battery (Fig. 11a) and the proper reorder is enclosed in an air-tight metallic case provided with an adjustable slot, in front of which sweep three light spots, their variable position carrying information. The photosensitive paper is turned on a drum and winds in the rear side of the slot, with one of the two constant rates transmitted by a clock mechanism provided with a periodically picked-up load (Fig. 11b; axonometric view – Fig. 11c).
Winding rate: v1 = 0.006 m/h
v2 = 0.300 m/h
Photosensitive paper hopper: 1 m
Load weight: 6 kg.
Key words: geodynamcis, geophysical instrument, underground observatory, crust deformation, Earth tides, tiltmetry.

MAGNETIC TAPE COUPLER FOR A BASED ON MPU-8080 DATA ACQUISITION
AND PROCESSING SYSTEM (MTC)

R. DOROBANTU, V. GHEMIGIAN
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

The MTC assures a high storage capability of the great bulk of data furnished by the continuous geodynamic recordings. The MTC accomplishes the DMA coupling of a TM – 100 – Ampex magnetic tape unit (MTU) to a data acquisition and processing Romanian made system (based on MPU – 8080). Control software of the MTU coupler is structured so as to allow the handling of a file-working system in a manner compatible with the Felix C – 256 series computer (Fig. 12).
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tides, data storage.

STRAINMETER TRANSDUCER UNIT (STU)

R. DOROBANTU1, DOREL ZUGRAVESCU1, M. BONATZ2, N. PUSCASU3
1Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest, Romania
2Institut für Theoretische Geodäsie der Universität Bonn, West Germany
3University of Bucharest, Bucharest, Romania

Realized of Romanian made components, the device achieves a high resolution (of the order of 0.5 nm) by an electro-mechanical and electrical remote control of the null-balancing. The sending unit displays and counts the digital pulses acting on the control system of the null-balancing. The receiving unit of the device has a storing and digital-to-analog conversion system, is built in a compact form and has a high reliability (Fig. 13a; axonometric view – Fig. 13b).
Sensitivity: 10 V/m (for a signal/noise ratio of 45 dB)
Delay time: 7 s
Nonlinearity: < 1%
Fidelity (distortion factor): < 1%
Thermal drift: 5% °C
Resolution in the electromechanical remote control: 50 nm
Resolution in the electronical remote control: 0.5 nm.
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tide, strainmetry.

STABILIZED SUPPLIER 16/6 V

R. DOROBANTU1, DOREL ZUGRAVESCU1, ST. FANACA2
1Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest
2Enterprise of Research Apparatus and Equipments, Bucharest

Exclusively realized of Romanian made components, the device is destined to supply the apparatus using a capacitive transducer (gravimeter, strainmeter, barometer) placed in geodynamical observatories equipped by the capacitive transducer. The device furnishes two stabilized electrical tensions, meant to supply the transducer as well as the termostatization (Fig. 14).
U0I: 16 V/0.5 A
The stabilization factor for the load fluctuations
0.15 IM ÷ IM: < 2x10
The stabilization factor for the network fluctuations
+ 10%
220 V – 15%: IN < 5x10
U0II: 6 V/2.5 A.
The stabilization factor for the load fluctuations
0.1 IM÷ IM: < 5x10
The stabilization factor for the network fluctuations
+10%
220 V – 15% IN: < 5x10
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tide, gravimetry, tiltmetry, strainmetry.

ADJUSTABLE STABILIZED POWER SOURCE 20 V/20 A (SPS)

R. DOROBANTU1, DOREL ZUGRAVESCU1, ST. FANACA2, D. HARTIA1
1Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest
2Enterprise of Research Apparatus and Equipments, Bucharest

SPS is destined to the charging of the buffer accumulators assuring an independent supply of the apparatus placed in geodynamical observatories, but is utilizable in other fields too. SPS allows us to obtain a rectangular external current-voltage characteristic, having adjustable limits of the stabilized voltage and of the maximum current flow (Fig. 15).
U0 (adjustable): 10 – 20 V
I0 (adjustable): 0 – 20 A
Stabilization factor for the load fluctuations
0.1xIM÷ IM: 10-3
Stabilization factor for the network fluctuations:
+ 10%
220 V – 15% IN: < 5x10.
Key words: geodynamcis, geophysical observatory, underground observatory, crust deformations, Earth tide, gravimetry, tiltmetry, strainmetry.

DEVIDE FOR THE FILTERING AND STORING CONTROL
OF THE GEODYNAMICAL DATA

R. DOROBANTU, DOREL ZUGRAVESCU, D. HARTIA, D. DELION
Centre for Earth Physics and Seismology, Department of Geodynamics, Bucharest

Realized of Romanian made components, the device is destined to the hardware filtering of the data furnished by the geodynamical sensors and to the scheduled control of the command of the information concerning storage moment, as well as of the time mark (GMT), on the punched paper tape (Fig. 16 a, c; axonometric view– Fig. 16b).
Scheduled triggering of sampling: 10 s – 24 h
Sampling interval: 0.1 – 1 s
Upper cut-off frequence: 0.3 · 10– 3 · 10Hz
Key words: geodynamics, geophysical instrument, underground observatory, crust deformations, Earth tide, gravimetry, tiltmetry, strainmetry.

QUARTZ CRYSTAL CLOCK

I. VISESCU, I. SERBAN, GH. ROTARU
Military Topographic Direction, Bucharest

Frequency (crystal oscillator Hewlett-Packard 10544 A): 10 MHz
Ageing rate: 0.5 · 10/day
Automatic synchronization by ratio signals: ± 1s
Comparison by TV method: ± 10 s
Size: 170 x 440 x 450 mm
Weight: 10 kg
Utilization: Astronomic and satellite observations (Fig. 17)
Key words: geodesy, astronomy, quartz clock, ratio synchronization, satellite observations.

HYDROPHONE PATTERN WITH PROPER GAIN FOR DIRECT UP-HOLE SHOTS
UTILISED IN WEATHERING-ZONES STUDIES
IN SEISMICAL PROSPECTING

V. VARODIN, I. GAUZIN, I. CRISTIAN
Enterprise of Geological and Geophysical Surveys, Bucharest

The built-in amplifier acts as an impedance converter for better crossfeed specification in signal transmission over long wet cables.
Hydrophone type MP – 7B sensitivity: 0.8 V/bar
Output impedance: 50
Maximum output signal: 0.75 V
Consumption: operation: 0.75 mA
stand-by: 1 A
Distance between sensors: 3 – 5m
Investigation depth: 100 m
Sensor mounted in a rubber sealed capsule with silicon oil attached to the unit body for protection and electrical insulation.
Unit dimensions: length 130 mm, 35 mm.
Key words: microseismic log, weathering correction.

PORTABLE PROTON MAGNETOMETER

Geophysical equipment research and development laboratory
Institute of Geology and Geophysics, Bucharest

The model MPP – 3S is a complete portable proton magnetometer for all man-carry field application, a rugged, light-weight and versatile instrument.
Sensitivity: 0.25 nT
Range: 20,000 – 90,000 nT.
Key words: globe physics, geophysical instrument, geomagnetism, geomagnetical observatory, geophysical surveys, magnetometry.

MARINE PROTON MAGNETOMETER MPM – 1S

Geophysical equipment research and development laboratory
Institute of Geology and Geophysics, Bucharest

Specially designed for use in marine environments (for measuring and recording the earth's total magnetic field intensity) it is suitable for marine geophysical prospecting, salvage work and submarine pipeline and cable surveys.
Sensitivity: 1 nT
Range. 30,000 – 90,000 nT.
Key words: globe physics, geophysical instrument, geomagnetism, geomagnetical observatory, geophysical surveys, magnetometry.