Project Results: Seismic Risk

Based on the generated GIS by all participants jointly, a �quality standard� of the geodynamic parameters describing pressure on a terrestrial surface is given. The geological, geomorphological, hydro-geological features of a modern relief which influence the stability of geosystems and also the intensity of an erosive partition, density of explosive infringements, zones of active breaks, borders of uneven-age structures, degradation of lake systems and small rivers are revealed. For definition of the geo-ecological potential of geosystems of the test areas "Kudara" and "Barguzin", the uniform system of the components connected to features of a modern relief, is considered by its geological structure, the landscape and socio-economic factors. The basis is now laid out to continue with GIS-modelling analysis.

By comparison of interferograms for polygon Bargusin, it was found that interferometric decorrelation in mixed coniferous and deciduous forests has an approximately constant level and does not depend on the time between satellite image acquisitions. It was calculated, that changes on the interferogram are adequate to increments of the relief of 3cm which can be linked to gravitational landslides of a large mountain massif (1 km x 1 km) downwards on an incline. This movement accompanied the preparation of an earthquake, which was measured on ground between the satellite image acquisitions.

In December 1999-Janiary 2000 on testing area "Kudara" and in August - September 2000 the joint field operations of the Russian and foreign participants of the project (K.Schmullius, A.Zakharov, D.Darizhapov, G.Tat'kov) for terrestrial revision of deciphering tectonic deformations, types of wood vegetation and soil are fulfilled. The places of development of wind erosion/ soil deflation, focies of forest fires, sites of mass wood cuttings down were inspected.

Selenga Geology and Earthquakes
Selenga Geology and Earthquakes
The overflow of salt water along those faults causes the salting of soil and appearance of halophytes geosystems in the south-western and north-eastern parts of Kudara testing area. Combining of marsh and steppe geosystems is connected with close surface location of subsoil water in valley and lakeside downturn. For the estimation of technogenetic loading, the areas under settlements, focies of forest fires, sites of mass wood cuttings down were singled out. In delta of Selenga river, the areas of deserting (the places of development of wind erosion/ soil deflation,) were localized. It was stated that as the result of soil deflation, the square of forests decreased. It is established, that the greatest seismic activity is characteristic for those faults and their fragments which planes coincides with the flatness of maximum tangent tensions: Chivyrckuy breakingof northern direction, breaking breaches of Barguzin gulf bottom, eastern fragment of sub longitude breaking in northern part of golodinski range, south-western part of tectonic connection of Barguzin and Ust�- Barguzin valleys.

The modern structure of a southwest part of Bargusin range was generated under influence of strain stresses of north- northwest directions. The structures of strains are well marked in a relief by fledging (secondary) Fault and can be decoded on radar images. The structures of strain are characterized by low seismicity, that doesn't accord to the level of maximum magnitude (M = 7.0) of Malochiwerckuy paleoseismodislocation.

The maxima of present seismicity is observed in northeast of peninsula Svjatoy Nos, where in a zone, that is adjacent to meridional Chivyrckuy shear-fault, the maximum development received the structures of compressions incorporated on Proterozoic gneisses as reversed fault.
The seismic activity of Bargusin seismic hazard zone is not very high and expresses in swarm of small earthquakes in a southern part of Bargusin hollow. Earthquake swarm is connected with confluence (connecting) of strike-slip fault, which have different directions and creation of grabens in area where regional faults of sublatitute and submeridional directions cross.

Copyright © by FSU Jena 2003-2004, Created by A. Kaspar