HR: 0800h
AN: S11A-0267    [Abstracts]
TI: Natural Hazards As An Indicator Of Post Seismic Activites In The Armenian Upland
AU: * Avanesyan, M
EM: hasmikonly@yahoo.com
AU: Durgaryan, R
EM: raffie_d@yahoo.com
AB: In seismically active areas the risk is high due to possible structural destruction and population loss as a result of a strong earthquake impact. Moreover, there are secondary earthquake related hazards such as landslides, avalanches, probable fires, explosions, chemical and radioactive contamination that make the situation worse. For seismically active mountainous countries like Armenia the induced post-seismic activity of landslides is still very important. Post-seismic activation of landslides and extensive deforestation are widely developed in the zone of catastrophic earthquake M=7.0 in Spitak in 1988 which occurred on the north-east of Armenia and destroyed a big number cities, settlements and special and significant facilities. After Spitak 07.12.1988; M=7.0 earthquake, the observers' interest was concentrated on gradually activating landslides that lie within the territory of Pambak-Sevan and Spitak active faults adjoining the Spitak earthquake epicentral zone. The Spitak fault was activated during the earthquake and formed a 37 km long surface rupture. From the tectonic point of view that phenomenon is known for long time. Under the impact of strong earthquake the slops that have "favorable" slipping angle loose their gravitational balance and slide-down destroying everything on their way. The lithological and structural criteria of geodynamic activity of these regions on the boundary of Late Mesozoic – Early Cenozoic are considered. In particular, data are presented on geological structure of the sites of "wild" coarse flysch, olistostrome horizons and intensive folding development. For the reconstruction of geodynamic situation in the region on the Meso-Cenozoic boundary the olistostrome horizons' formation is considered. The spatial relation of contemporary active structures, including the seismogenic ones, (scarps, ledges, ruptures, landslides with the areas of Meso-Cenozoic activity manifestations) is shown and their inherited character is proved. For reliable seismic hazard assessment in young seismo-active folded regions, including the zones of Alpine tectogenesis, along with recognized seismological and seismotectonic criteria it is proposed to use the considered lithological and structural preconditions. On the other hand the task becomes more complicated if we consider it in environmental aspect. During the observations that we have done in previous years we occasionally fixed that in the mentioned zone nearly all landslide bodies had forest cover. It forces us to consider the landslide activity also as a result of extensive deforestation during the post-communistic and transitional period in our country. The comprehensive interpretation of this problem we propose and new results that can provide important ways for landslide disaster risk reduction strategy.
DE: 7209 Earthquake dynamics (1242)
SC: Seismology [S]
MN: 2007 Fall Meeting