Geodimanics of Talas-Fergana Fault
Geodynamics of Talas-Fergana Fault, Tien Shan and Natural Disasters on the Territory of Central Asia
Tech Area / Field
- OBS-NAT/Natural Resources and Earth Sciences/Other Basic Sciences
- ENV-SEM/Seismic Monitoring/Environment
8 Project completed
Senior Project Manager
Rudneva V Ya
Institute of Seismology, NAS, Kyrgyzstan, Bishkek
- Institute of Dynamics of the Geosphere, Russia, Moscow
- Stanford University / Department of Geological and Environmental Sciences, USA, CA, Stanford\nInstituto Nazionale di Geofisica e Vulcanologia, Italy, Rome\nUniversita degli studi di Milano-Bicocca / Department of Geological Science and Geotechnologies, Italy, Milan
Project summaryThe Project Objective is composition of geological/geophysical model of deep structure of Talas-Fergana Fault and estimation of its effect on occurrence of natural disasters in densely populated areas of Central Asia.
The largest in continental Asia seismically active Talas-Fergana Fault pides the Tien Shan mountain system into eastern and western portions. In north and east the faulting zone stretches along the densely populated and economically undeveloped region of Central Asia – Fergana Valley. The problems of effect of recent geodynamics and deep structure of Talas-Fergana Fault on occurrence of natural disasters have not been systematically considered yet. At the same time, recent geodynamical processes and deep structure of active faults are basic factors of natural/technogenic disasters’ occurrence for many regions all over the World. Urgency of the project is also related to periodical strong earthquakes, landslides, rock falls and mud flows within the faulting zone and its segments that occupies the territory of 750 km in length and 50 km in width trending north-westward. Strong paleo-earthquakes were resulted in formation of large dammed lakes Karasu and Sarychelek. These natural disasters constantly affect the ecologically dangerous radioactive tailing dumps (Mailisuu, Sumsar, etc.), the largest in the region Toktogul reservoir (V=19 км3) and Naryn Coordinated Hydroelectric System providing electricity and water for southern Kyrgyzstan, Kazakhstan, Uzbekistan and Tajikistan.
Novelty of the study is in determination of deep geological/geophysical structure of the faulting zone and selection of the most active faulting segments providing high-level seismicity and exogenic disasters.
The basic scientific purposes of the Project include development and composition of a complex geological/geophysical model of the fault deep structure as well as estimation of effect of the fault and its segments on occurrence of natural/technogenic disasters.
The largest in Central Asia catastrophe – mass landsliding occurred along the foothills of Talas-Fergana Range after destructive earthquakes of 1992 (Kochkorata, MS=6.3 and Suusamyr, MS=7.3) and as result of heavy raining in spring 1994. 120 men were killed and 150 000 men were resettled. Economical damage was measured for 50 mil. US dollars (Korjenkov, 1996; Bogachkin et al., 1997; Ghose et al., 1997; Korjenkov, Lemzin, 2000).
Building of tunnels for railways within the zone of Talas-Fergana Fault connecting countries of Central Asia to China and further to Pacific ocean is in the basis of State Doctrine “Silk Way” by President of Kyrgyz Republic A.Akaev. Thus, occurrence probability of both natural and natural/technogenic disasters is high within the active faulting zone.
There is international scientific experience on study of San Andreas (USA), Avatera (New Zeland), Anatoly (Turkey), Altyntag (China) and other faults (Arrowsmith et al., 1998; Lensen, 1968; McCalpin, 1996).
The Project authors have the beginning of the study which have been gained during the following projects: PL-96-3202 JNCO COPERNICUS «Landslides on the territory of Kyrgyzstan triggered by earthquakes» (1998-2000), INTAS–96-1923 «Recent deformation and denudation in Pamir and Tien Shan, Kyrgyzstan» (1998-2001), ISTC # KR-155 «Velocity structure and elastic properties of rocks in source zones of strong earthquakes in Tien Shan» (1999-2001), ISTC # KR-357 «Active faults and strong earthquakes in Tien Shan» (2001-2003).
Talas-Fergana transorogenic fault is in the focus of interest of many geologists and geophysics occupied with problems of intracontinental orogen in Asia (Burtman, Molnar et. al., 1963, 1996; Reigber et.al., 2001; Trifonov et.al., 1992; Chedia et.al., 1986). The faulting zone is clearly traced from satellite imagery and crosses temporary channels and small rivers flowing downward the Fergana and other ranges. There is offset of the channels north-westward from 25-30 m up to 100 m.
According to results of previous works carried out for the period 1991-2003 (Korjenkov, 1993; Mamyrov et.al., 2002) the zone of Talas-Fergana Fault has complicated structure. Considering character of deep structure and recent activity the zone can be pided into several segments. In addition to surface geological/tectonic and seismotomographic data a great volume of geophysical and geodetic data as well as geophysical modeling of the faulting zone is necessary for decision of basic problems of recent dynamics of the fault and estimation of its effect on origin of natural/technogenic disasters. In this connection one of the important problems of the Project is modeling the deep structure of the faulting zone on the basis of complex interpretation of seismis/tectonic, seismological, seismotomographic, geothermic, geoelectrical and magnetometric data. The other important problem is correlation of deep tectonic/physical processes to exogenic phenomena: landslides, rock falls and mud flows. It is also supposed to develop practical quidelines for protection of population and various constructions from possible natural/technogenic catastrophes.
Thus, the study proposed will allow creation of the recent geological/geophysical model of Talas-Fergana faulting zone, and development of practical guidelines for protection of population of one of the most densely populated regions of Central Asia – Fergana Valley from possible natural/technogenic disasters.
Decision of the following tasks is supposed for achievement of the project aim:
- Study of geological/tectonic structure and evolution of the faulting zone.
- Study of seismic velocity heterogeneities and geophysical fields of the faulting zone.
- Study of recent geodynamics of the faulting zone.
- Development of a model of geodynamic processes, and natural and natural/technogenic disasters within the faulting zone.
- Development of practical guidelines for protection of population from possible natural/technogenic catastrophes.
- Geological/structural map of Talas-Fergana faulting zone will be composed and its evolution will be studied;
- Deep velocity and geoelectrical heterogeneities of the earth crust structure as well as probable PT-conditions and material structure will be defined;
- Recent geodynamics of the faulting zone and its effect on origin of natural disasters will be studied;
- Modeling bases for geodynamic processes and natural/technogenic catastrophes within the faulting zone will be created;
- Geological/geophysical and geodynamical models of Talas-Fergana Fault at the modern stage of development of continental lithosphere will be created;
- Spice-time laws of origin of earthquakes, landslides and mud flows will be determined, and practical guidelines for protection of population from possible natural/technogenic disasters will be developed.
Research methods: geological, geophysical, seismological, aero- and space imagery, engineering/geological, climatic, statistic methods of time series study.
Experimental data: the bank of geological, geodetic, geophysical and seismological data; the bank of data of number and scale of natural/technogenic disasters of the Ministry of Ecology and Emergency, Kyrgyz Republic.
Observational system: seismic and geophysical stations of Central Asian countries (40), GPS stations (30), aero- and space imagery, landslide preventive and hydrometeorological stations; the period of observations - 1930-2003.