HR: 1340h
AN: S33B-1102    [Abstracts]
TI: Multidisciplinary Approach To Earthquake Prediction Using Vibroseismic Sounding Of Seismic-Prone Zones
AU: * Alekseev, A
EM: alekseev@sscc.ru
AF: Institute of Computational Mathematics and Mathematical Geophysics SB RAS, pr.akad.Lavrentieva, 6, Novosibirsk, RUS 630090
AU: Kovalevsky, V
EM: kovalevsky@sscc.ru
AF: Institute of Computational Mathematics and Mathematical Geophysics SB RAS, pr.akad.Lavrentieva, 6, Novosibirsk, RUS 630090
AB: The existence of a near-surface crack formation zone (besides a source zone) was predicted by numerical modeling of the initial stage of rock destruction in the concentration zone of tectonic stresses. This made it possible to explain some contradictions of the multidisciplinary approach to earthquake prediction. It was shown that one should admit the possibility of formation of numerous geophysical anomalies-precursors due to changes in the fluid saturation, electric conductivity, and density of the surface crack formation zone. These anomalies can reflect the development of the surface zone, although they are only indirectly connected with the stresses and crack formation in the source. To find quantitative relations between anomalous geophysical fields at the surface and the field of stresses and deformations in the area of the source, it was proposed to use the "active seismology method". This method allows vibroseismic monitoring of the stressed-deformed state of the Earth's crust mass involved in the crack formation and other rheological changes in the vicinity of the future source. This multidisciplinary prediction technology implies the medium-range determination of the epicenter areas of developing sources by using geodetic and other anomalies and subsequent detailing of the source rheology monitoring by vibroseismic sounding of selected zones. The combination of the data of deep seismic monitoring with rich information about fields-precursors at the surface opens up new possibilities for short-range prediction. Now, an experimental system of active vibroseismic monitoring of the Earth's crust, which includes powerful 100 - ton vibrators, mobile seismic arrays for the recording of vibrosignals, and computer systems for the processing of vibromonitoring data is being developed. The system was tested in experiments, where the influence of the Earth's tidal deformations of the crust (of the order of 10-7) on the velocities of seismic waves was determined. These experiments have shown that the seismic monitoring system with powerful vibrators has high sensitivity and allows us to select relative variations of velocities of seismic waves of about 10-5 - 10-6 in an area of 300-500 km around the source. It makes possible direct monitoring of the state of stresses in an area of 100 000 km2 to detect regions and phases of critical stresses as an earthquake precursor. Some local geophysical anomalies are not precursors of direct action. They mainly characterize the dynamics of the fissured surface zone, but not the rheology of the source. It is likely that the most accurate method for estimating the relation between the surface and source dilatancy zones by using a common field of stresses is vibroseismic monitoring of changes in the anisotropy of the intermediate medium's layer in seismic prone zones. The influence of geological peculiarities of this zone can be investigated by creating vibroseismic test sites in heterogeneous zones (transformed fracture; rift zone; intraplate zone, etc.). The coordination of works by the International Cooperation Program of existing test sites in Parkfield, (California, USA), Baikal, (Siberia, Russia) and Hebei Province (China) can provide the necessary information.
DE: 7223 Seismic hazard assessment and prediction
DE: 7294 Instruments and techniques
DE: 7200 SEISMOLOGY
DE: 7209 Earthquake dynamics and mechanics
SC: Seismology [S]
MN: 2004 AGU Fall Meeting