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Dynamics of the Lithosphere

#2652


Strain and Stress Fields in the Lithosphere in Tectonically Active Areas of Central Asia

Tech Area / Field

  • OBS-GEO/Geology/Other Basic Sciences
  • INF-SOF/Software/Information and Communications

Status
3 Approved without Funding

Registration date
10.12.2002

Leading Institute
Institute of Geology and Mineralogy, Russia, Novosibirsk reg., Novosibirsk

Supporting institutes

  • Joint Institute for High Temperatures RAS / Scientific Station, Kyrgyzstan, Bishkek\nVNIITF, Russia, Chelyabinsk reg., Snezhinsk

Collaborators

  • University of Colorado / Department of Geological Sciences and Cooperative Instiute for research In Environmental Sciences (CIRES), USA, CO, Boulder\nPurdue University / Department of Earth and Atmospheric Sciences, USA, IN, West Lafayette\nGeoForschungsZentrum Potsdam / Section 1.1 Geoprocesses and GPS-Technology, Germany, Potsdam

Project summary

The aim of the project is to develop a new technique for the exposure of abnormally high stress zones in the lithosphere as places of future earthquakes. The technique will exploit numerical modeling of the present-day states of strain and stress of the lithosphere taking into account their evolution in time and space. Numerical models will use current geological and geophysical data to set boundary conditions and to verify obtained results. The application of this technology in Central Asia will give new information about the origin of earthquakes there. It will advance seismic prognosis and improve the reliability of separating artificial and natural events.

The study area will include the following structures: the Tien Shan, the Tarim plate, the Djungar basin, the Altai-Sayan folded region, and the Hangai plateau with surrounding ridges of Mongolian Altai. In the future the area will be extended to the Mediterranean including the territories of Pakistan, Afghanistan, Iraq, and Iran (areas of CTBT concern).

According to the current point of view, the origin of seismic activity in Central Asia is mostly connected with the collision of the Indian plate with the Asian continent, which consists of a complex of rigid blocks-microplates and more deformable belts between them.

The project consists of three main steps. The first one is the construction of a reliable block model of Central Asia on the basis of 2D modeling of the lithosphere dynamics. This step will provide block boundaries and surrounding zones of plastic strains.

The next step is the developments of a 3D numerical code for the calculation of stresses and strains in the lithosphere. This code will take into account the block boundaries obtained at the first step, the dependence of the lithospheric material viscosity on temperature, and the existence of inclined faults between blocks. Boundary conditions for the study segment will be determined from the velocity field obtained from the GPS data. The model will be verified by comparison with observations.

The third step consists in the calculation of stresses and strains from the annual variations of displacement velocities measured at GPS sites. Revealing zones of abnormally high stresses will help identify locations of potential earthquakes. The successful implementation of this step will improve the mid-term prognosis of seismic activity.

Besides a large computational and theoretical work, the project provides for field observations that are of great importance for the research. The project plans to carry out the GPS measurements within a wide territory of Central Asia and the magnetic-telluric sounding.

The results of the project will be of great importance for the fundamental science. The map of microcontinents and orogenic belts will provide new information about the tectonic evolution of the lithosphere in Central Asia. It can be used for the evaluation of the mantle influence upon the lithosphere structure and the solution of other problems of deep geodynamics. The investigation of abnormally high strain-stress zones will help understand the physics of earthquakes.

Project participants have rich experience in the investigation of lithosphere dynamics in intercontinental areas and the numerical modeling of deep processes. They developed original models of material behavior in different geodynamic conditions and have necessary information a complex of geological and geophysical data, GPS observations, focal mechanisms of earthquakes in Central Asia etc. The participating teams have most programs to be used in the project. Moreover, the participants of the project developed original methods for investigating the 3D mantle structure using seismic tomography. All necessary programs and data to model the thermal state of the lithosphere are available. The visualization of modeling results and different geophysical fields will be made on the basis of tools developed by project participants.


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