Nonlinear dynamics of crustal blocks and faults and earthquake occurrences in the Transcaucasian regionстатья
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Дата последнего поиска статьи во внешних источниках: 8 декабря 2021 г.
Аннотация:The Caucasus is a part of ongoing collision of the Arabian and Eurasian plates, where moderate to strongearthquakes caused significant losses of lives and livelihood in the past. To better understand seismic hazard inthe region, we develop a model of block-and-fault dynamics for Transcaucasia, the largest part of the Caucasus tothe south of the Greater Caucasus Mountains, to simulate regional earthquakes. The model structure is developedby employing the results of the morphostructural analysis to delineate crustal blocks and the geodetic observationson crustal movements in the region. The model incorporates a nonlinear rate-dependent slip of thefaults separating the blocks. A set of numerical experiments has been performed to address the followingquestions: (i) where strong earthquakes occur and what their reoccurrence time is; (ii) how rigid crustal blocksreact to the Arabian plate push and to movements of the ductile part of the crust in Transcaucasia; and (iii)whether the fault slip rates and the block displacements in the model correlate with observed GPS-velocities. Themodel results confirm that the contemporary crustal dynamics and seismicity pattern in Transcaucasia are determinedby the north-northeastern motion of the Arabian plate relative to Eurasia and by the movement of theductile crust underlying the rigid crustal blocks. Variations in the rheological properties of the fault zones and/orof the ductile crust influence the pattern of seismicity. The number and maximum magnitude of syntheticearthquakes change with the variations in the movements of the crustal blocks and in the rheological propertiesof the lower crust and the fault zones. The model results can be used in comprehensive seismic hazard assessmentof the Caucasus region based on instrumentally observed, historical and synthetic seismicity.