TEHNICI SI METODOLOGII INOVATIVE DE EVALUARE  A RISCULUI DE HAZARD NATURAL (CUTREMURE SI ALUNECARI DE TEREN)

 

	RESULTS OF THE STAGE I              Analysis of the morphologic, lithologic, geologic and geophysical data specific to the two types  of hazard                    The results of the first stage are centered on constructing a data base used to identify hazard operators (variables, indices and indicators) which enable that some coherent and relevant conexions, between the two geodynamic processes and various physical parameters computed after the electromagnetic monitoring in real time,  to be achieved. The interdependence relationship between the tectonic activity and anomalous changes of the electromagnetic, electric and geomagnetic parameters, characterizing the Earth’s lithosphere is, generally, well known. In active geodynamic zones, emphasized by means of earthquakes and landslides,  the anomalous behaviour of these parameters may be mainly generated by stress or physical and chimical changes occured at various depth levels and represents the probable cause for the setting up of the pre-crisis state in these areals. In this context, the multi-parametric electric, magnetic and electromagnetic information, carried out up to now for the two types of hazard, which may lead to the assessment of the potential risk level, will create a data base considered as „input” for achieving the National Index, by identifying variables, indices and indicators. This electromagnetic data base, represented by multi-parametric space-temporal distribution, materialized in representative geodynamic models  and time series, respectively, contains the following information: Displacement of the electromagnetic geotraverses and the coordinated of their ends; Resistivity and phase distribution versus the period (electromagnetic sounding curves) for each crossed tectonic traverse; Pseudosections with the electromagnetic spatial distribution; 2D resistivity distribution at lithospheric level, carried out by means of the numerical modelling by applying an algorithm based on finite element; 2D modelling of the resistivity distribution; Electromagnetic tomographies elaborated at various depth levels, to emphasize the characteristics of dimensionality  for the investigated structures, and, to establish their structural  relationship with the arrounded structures; Spatial distribution (polar diagrams ) of the impedance tensor , with major role in establishing the direction of a geodynamic structure. The landslides classification within an unitary system is difficult, taking into account that their extent is very large and, at the same time, generates a lot of microformes of relief  under the circumstances in which the motion affects not only the allteration cover, but their subasment, too. The classification criteria are determined by the final aim, by the relief microforms, and type of movement of the materials on slope. In genesis and development of in a body movement processes, more factors, which depending on their role may be gruped in passive and active, concur. In the frame of the passive factors (favority factors, tendency/predisposition factors) there are the lithology and the structure of the subasment, with their components - representing elements that need the action of other internal or external factors  to modify their dynamic properties. Also, in the frame of the active factors come preparation factors and triggering factors. A series of agents like water and air contribute decisively to the genesis and development of  in a body movement processes, by means of some specific processes which are running individually or in concerted mode. At the same time, it has not to be forgotten the human factor (vibrations generated by road traffic or railway traffic, explosions, undermining or overcharge of the slopes), and neotectonic or seismic movementss effect, too. The  GIS techniques offer an efficient instrument for the integrated  mangement of the in a body movements, thus being possible to achieve the mapping, evaluation on-line, monitoring,  to offer  solutions or to make  warning . Among the most important avantages offered by GIS, the following ones  could be mentioned: completation  or correction of some parameters that make up the data base attached to a layer, in case that they might be modified (distances, volumes, areas, temperatures, quantities of precipitations, magnitudes of telluric movements, etc.), what, finally, enable to adapt the map  to the new information carried out; between the initial and actualized data it is possible to make interpolations in conformity with  various algorithms, with high precision, which make possible to delimit some areas with homogeneus characters. By succesive highlights of various development stages (temporal series) the evolution tendency of the processes could be emphasized. For using simultaneously the numerical or graphical data base, the direct computation represents the rapidest way to find out (both on raster and vector) dimensions like distances ( among points, lines, poligons), areas, volumes; from the georeference moment, the scale may be used in any measure unit. Also, it was made up the seismological data base (catalogues of events, solutions of focal mechanisms, acceleration levels of the ground owing to the earthquakes, maps of seismic intensity and seismic hazard) and the data base regarding the structure of the crust and upper mantle in Romania. Among them, the most important are the eaarthquakes catalogues, particularly for Vrancea intermediary depth earthquakes (Mw³5,0), and then  for the crustal ones (Mw³4,0). The same importance have the catalogues with solutions of the focal mechanisms, that beside  the other seismological data characterize a certain seismogenic area and give an image about the spatial orientation of the foci, breaking process mechanism, release mode of the tectonic tension, scalar properties of the source parameters, etc. Together with Vrancea zone, known by its strong earthquakes (Mw³7,0) generated at intermediary depth (>60km), zones with crustal seismicity from Banat, Fagaras and Baia Mare are presented, too. The maps of seismic intensities are the result of synthesis of the macroseismic local information or/and instrumental concerning the level where a major earthquake was felt, in various points of the territory. A sinthesis of the seismological data correlated with tectono-geological and geophysic data made possible to achieve a  Romania’s seismic hazard map, which will help to establish the development policy of a region, taking into account the potential effects of the earthquakes that could affect it. From a historical perspective, data concerning the deep structure of the territory and data necessary to evaluate the seismic effect for deterministic hazard  are presented. Since the first consistent information regarding the deep structure supplied by seismology and gravimetry during 60 years, are reviewed the main works devoted to this goal: the seismic geotraverses of refraction during 70’s, of reflexion seismics during 80’s, refraction profiles during 80 and 90’s, profiles of refraction for Vrancea zone, together with a seismic tomography experiment, magnetotelluric investigations and sinthesis data concerning the lithospheric structure in Romania. The bibliographic lists indicate the sources of the data base. Published articles: D. Stanica and M. Stanica, Modelling of Block and Fault Systems of the Active Vrancea Zone (Eastern Carpathians Romania); Evidence of the Geodynamic Torsion Process, The 9th Workshop on Non-linear Dynamics and Earthquakes Predictions, the Abdus-Salam ITCP, 01-13 October, 2007 ( http://www.agenda.ictp.trieste.it/smr.php , 1964-3) D. Stanica, M. Stanica, and C. Diacopolos, Real time ground-base monitoring system for earthquakes and associated natural hazard assessment and risk mitigation, The 9th Workshop on Non-linear Dynamics and Earthquakes Predictions, the Abdus -Salam ITCP, 01-13 October, 2007 ( http://www.agenda.ictp.trieste.it/smr.php , 1964-1) D. Stanica and M. Stanica, Specific electromagnetic approaches related to the short-term precursory parameter associated to intermediate depth seismic events (Vrancea zone, Romania), The 9th Workshop on Non-linear Dynamics and Earthquakes Predictions, the Abdus -Salam ITCP, 01-13 October, 2007 ( http://www.agenda.ictp.trieste.it/smr.php , 1964-2) Scientific Communications: D. Stanica, Associated natural hazards: earthquakes and landslides reflected by the electromagnetic data, Third International Conference CEI, Bucharest, Romania, 24-26 October, 2007 V. Raileanu, F. Hauser, A. Bala, W. Fielitz, C. Prodehl, C. Dinu, M. Landes , Deep seismic sonding across the Vrancea region, International Symposium on Strong Vrancea Earthquakes and Risk mitigation, October, 4-6, 2007, Bucharest V. Raileanu, C. Dinu, E. Popescu, V. Diaconescu, B. Grecu, Crustal seismicity and associated tectonics in the W and NW of Romania,The Third International Conference: SCIENCE AND TECHNOLOGY FOR SAFE DEVELOPMENT OF LIFE LINE SYSTEMS, Progress on seismic and geotectonic modeling across CEI territory and implications on preventing and mitigating seismic risk. October 24th - 26th, 2007, Bucharest . D. Stanica and M. Stanica, Modelling of Block and Fault Systems of the Active Vrancea Zone (Eastern Carpathians Romania); Evidence of the Geodynamic Torsion Process, The 9th Workshop on Non-linear Dynamics and Earthquakes Predictions, the Abdus -Salam ITCP, 01-13 October, 2007 D. Stanica, M. Stanica, and C. Diacopolos, Real time ground-base monitoring system for earthquakes and associated natural hazard assessment and risk mitigation, The 9th Workshop on Non-linear Dynamics and Earthquakes Predictions, the Abdus -Salam ITCP, 01-13 October, 2007 D. Stanica and M. Stanica, Specific electromagnetic approaches related to the short-term precursory parameter associated to intermediate depth seismic events (Vrancea zone, Romania), The 9th Workshop on Non-linear Dynamics and Earthquakes Predictions, the Abdus -Salam ITCP, 01-13 October, 2007