YAKUTIA

Abstract

. The paper presents the results of monitoring seismicity in Yakutia in 2013 based on the data from 24 digital seismic stations. A total of 5197 seismic events with Кp=6–15 are detected. A map of earthquake epicenters is compiled showing their distribution in different areas. Two major clusters of seismic events are recognized. The first one corresponds to the Arctic-Asian seismic belt (AASB) extending across the Laptev Sea shelf and the north eastern Asian continent towards the Sea of Okhotsk. The second Baikal–Stanovoy belt in the south of the region is traced from Lake Baikal through the Stanovoy Highlands and the Stanovoy Ridge to the Sea of Okhotsk. In South Yakutia, the Olekma–Stanovoy zone (OSZ), which makes the eastern part of the belt, is considered. Both belts form boundaries of major lithospheric plates. The first belt separates the Eurasian and North American plates, while the other divides the Eurasian plate from the Amurian one. The minimum seismic level is recorded within the OCZ, with no more than 0.04 % of the total seismic energy re-leased during 2013. The maximum seismicity is noted in the AASB with released energy making up 99.9 % of the total amount. That abrupt change in seismicity is due to the occurrence here of three strong earth-quakes, Ulakhan-Chistay, Ilin-Tas (Abyi), and Tas-Khayakhtakh with the intensities VII-IX in the epicenters (MS=4.9–6.9). The epicentral zone of the Tas-Khayakhtakh event (MS=4.9) that occurred on May, 2013 is considered in more detail. The motion in the source of this event indicate thrusting along the Dogdo fault. All the shakes took place within the Chersky Range, in the zone of influence of major faults of the Kolyma–Indigirka system (Ulakhan, Dogdo, Ilin–Tas) under conditions of NE compression (regime of interplate collision and transpression ). Seismotectonic relations, macroseismic data, and earthquake focal mechanism pa-rameters are discussed.