Seismotectonic of the Issyk-Kul Depression
Quaternary / Subrecent seismotectonic activities in the Issyk-Kul depression: Its impacts upon drainage diversions, lake level and building constructions
Tech Area / Field
- ENV-SEM/Seismic Monitoring/Environment
3 Approved without Funding
Kyrgyz-Russian Slavonic University, Kyrgyzstan, Bishkek
- Stanford University / Department of Geological and Environmental Sciences, USA, CA, Stanford\nUniversity of Portsmouth / School of Earth and Environmental Sciences, UK, Portsmouth\nUniversita degli studi di Milano-Bicocca / Department of Geological Science and Geotechnologies, Italy, Milan
Project summaryKyrgyzstan is high-mountain republic, located on the territory of the Tien Shan orogen formed in result of collision processes between India and Eurasian lithospheric plates. Prior researchers reached some results in characteristic of active faults, able to produce destructive earthquakes within the Kyrgyz Republic. Main faults are pided into inpidual segments, presenting inpidual seismic sources. Segmentation of faults is the main uncertainty of seismic hazard assessments.
Annually about 3000 earthquakes occurred at the territory of the Kyrgyz Republic. The last 125 years in the North-Eastern Tien-Shan, where the Issyk-Kul depression is located, and several destructive earthquakes took place: Chilik (M=8.3) in 1889, Kemin (M=8.2) in 1911, Kemin-Chui (M=6.9) in 1938, Sary-Kamysh (M=6.8) in 1970, Djalanash-Tup (M=6.8) in 1978, Baisorun (M=6.1) in 1990. These destructive earthquakes are separated by small time intervals, which is an evidence showing that this region is one of the most seismically hazardous in Kyrgyzstan.
Preliminary investigations in this area have indicated the presence of strong ancient and historical earthquakes, which took place both on northern and southern coast of Issyk-Kul depression.
If to compare with modern strong earthquakes their parameters (epicenter, depth of source, magnitude and intensity) are quickly got using modern high precision seismic stations, but we can only get information about ancient earthquakes by doing detailed researches of such natural structures as: paleoseismic deformations, deformation of young terraces, seismic convolutions, drainage persion and etc. Geological and geomorphologic characteristics of above named structures, received during field researches with help hi-tech equipment, will help to define epicenter, time and force of ancient earthquakes, which are very important for joint analysis with modern earthquakes.
All occurred strong earthquakes were felt on territory of several thousand square kilometers. These seismic catastrophes left traces in the relief and underlying sediments, which will be investigated in detail during close collaboration with our foreign collaborators. The reasons of their appearance will be also decoded.
During the elaboration of the project modern technologies in geology, geomorphology and seismotectonics will be used. In particular during the investigation of deformed terraces differential GPS equipment will be used. Obtained dates on detail mapping and profiling permit to exactly define the slip rate of inpidual areas of earth crust, where active faults are located. Also we will take geological samples from lake and river terraces for dating their ages of deformation. Taken dates permit to define the ages of last strong earthquakes. We will use the method of trenching to determine intervals of recurrence of strong earthquakes. For investigations of level oscillation of Issyk-Kul lake the method of mathematic modeling will be used, in order to define the mechanism of their forming.
In researching the ancient earthquakes the method of archeoseismologics investigation is important. Studying the destructives of ancient cities and monuments in detail allows determining the genesis of their seismogenic destruction or other type of genesis. Here also the method of dating absolute ages of destructions ancient cities will be used and these data will be compared with some seismic events.
Realization of this project permits to improve the methods of studies in geological, geomorphologic, and seismotectonic sciences. At large all these investigations will be devoted to assessment of seismic hazards of Issyk-Kul basin using new methods. The obtained results definitely will be used for creating the map of seismic zoning of region.
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