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Earthquake’s Source Mechanisms

#KR-776


Earthquake’s Source Mechanisms and Stress-Strane State of the Earth Crust of Tian Shan on the Territory of Kyrgyzstan

Tech Area / Field

  • ENV-SEM/Seismic Monitoring/Environment
  • OBS-NAT/Natural Resources and Earth Sciences/Other Basic Sciences
  • PHY-SSP/Solid State Physics/Physics

Status
3 Approved without Funding

Registration date
06.08.2001

Leading Institute
Institute of Seismology, NAS, Kyrgyzstan, Bishkek

Collaborators

  • United States Departament of the Interior, USA, CO, Denver\nInternational Institute of Seismology and Earthquake, Engineering Building Research Institute, Japan, Tsukuba

Project summary

The purpose of the project – generalize seismological data on main parameters and source mechanisms of earthquakes of Tian Shan within the framework of the theory of a strain and stresses for the performance of stress-strained state of earth crust and to affix them on a problem of an estimation of an extent of seismic hazard of territory of Kyrgyzstan.

Stress-strained state (SSS) of earth crust at different scale levels introduces huge concern from the point of view of problem and fundamental knowledge in sciences about the Earth. The reconstruction of modern strains and stressstate tectonic of fissile locale gives some submissions about driving forces, nature and directivity tectonic of processes at a global and regional level. The study of stress-strained state of earth crust and rock sphere as a whole has scientific and practical value at an estimation of seismic hazard, solution of a problem of the forecast of earthquakes and other geodynamic debacles, by looking up, exploration and digging of mineral resources, at designing and exploitation of underground structures. The tendered studies are directional on analysis of stress-strained state of earth crust of Tian Shan on data of up to data and modern moves, dodges of the centers of earthquakes.

The seismic source – source of seismic waves is one of major plants of study in a seismological science. The study of processes happening in the sources of earthquakes, aggregates problems of a seismology, geotectonics and mechanics of continua. The mining of a method of share analysis of these datas is connected to primal problems of a seismology and tectonics, first of all with analysis of conditions both reasons of originating of earthquakes and link of seismicity with tectonic by process, and also physics of seismic waves and constitution of the Earth. It is known, that the earthquakes introduce development of modern tectonic moves on no-bottoms. Therefore seismological datas on dodges of the centers of earthquakes have apparent concern for plutonic tectonics and forecast of seismic hazard. In a methodical ratio the considered problem is referred, first of all, to a dynamic theory of elastic strength permitting to link processes in the center with a host material, observed on a surface by seismic waves.

Basis for implementation of the present program are the own materials collected for last two decades and, first of all, catalog of dodges of the centers of earthquakes of Tian Shan, and also other geological and geophysical materials.

On territory of Central Asian republics, including Kyrgyzstan rather already seismological observations for a long time are carried out, the parameters of the sources of earthquakes are instituted and the catalogs of seismic events are compounded. The seismic zoning of territory of Kyrgyzstan was conducted, basically, on seismostatics to data with allowance for geologies of region. However, the notice to usage of dodges of the centers of earthquakes for operations on seismic zoning of territory was a little given. The seismological parameters (source mechanisms of earthquakes and seismic regime of territory) were not compared among themselves within the framework of definite idealized reasons with the purposes of understanding physics of earthquakes. In this direction are present while simple operations K.I.Kuznetsova [Kuznetsova, Muraliev, etc., 1995] and writer of the given project [Muraliev, 1989].

Thus, the urgency of tendered study is instituted by conducting analysis of stress-strained state of earth crust of Kyrgyzstan on a complex of datas. Such approach allows to correlate data seismologies with datas of geodesic, geophysical and geologic studies, before held on Tian Shan and enables to elaborate of physical submissions about seismic process which is flowing past in tectonic active region.

Problems of the project.

During realization of the project the following problems are decided:

1. Making more precise of determination of source mechanisms of earthquakes of Tian Shan with allowance for of new accounts of angles of an exit of seismic rays and with the help of a computer program, designed Japanese seismologists.

2. Creation of the unitized database about source mechanisms of earthquakes and constructing of their maps.

3. Recognizing of underground explosions on substantial records of the seismic phenomens on the seismograms; compiling of the catalog underground explosions.

4. Accounts of a tensor seismotectonic of a strain (STD) for investigated territory; constructing of the quantitative pattern of maps a reductant of a tensor of speed STD.

5. Transferring from STD to a stress state of geologic environment and confrontation of results to results geodesic and геолого-geophysical studies, before held on Tian Shan.

6. Constructing of a modern field of the SSS of earth crust and with a consequent application it to an estimation of seismic hazard of investigated territory.

Methods.

For determination of source mechanisms of earthquakes the idealized pattern of the seismic source Honda-Vvedenskay – dual dipole without the moment will be utillized. The computer program, designed Japanese seismologists at TBIC (Japan) will be utillized.

The identifying of underground explosions is made by a plot method at visual reading of substantial seismic records. The long-term experience seismologists the seismograms will be utillized.

For accounts of a tensor seismotectonics of strains the methods U.V.Riznichenko (1965), B.V.Kostrov (1974) and S.L.Unga (1979) will be utillized.

The modern field of the SSS for territory of Kyrgyzstan will be plotted with applying of a computer program GIS Arc View – Intelligence system of know-how.

Expected results:

– the unifized database about source mechanisms of earthquakes Tian Shan in the international format;


– the catalog of underground explosions;
– maps of source mechanisms of earthquakes, seismic activity and STD for territory of Kyrgyzstan;
– map of a modern field of the SSS of earth crust of Kyrgyzstan with usage of datas seismological and geological-geophysical studies and with applying of a computer program - Intelligence system, GIS Arc View;
– scientific basis for further of development investigating on physics of earthquakes will created.


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