SEISMICITY of YAKUTIA in 2018–2019

Abstract

According to the information received from 20 stationary digital seismic stations of the Yakutia Branch of Geophysical Survey of the Russian Academy of Sciences, two-year (2018–2019) seismic monitoring of the territory of the Republic of Sakha (Yakutia) was carried out. During this time interval, more than 730 earthquakes with an energy class of KR≥7.2 (magnitude M≥1.8) were registered. During the previous two years, their number was 801. Manifestations of seismicity fixed the spatial position of the contact zones and their constituent blocks of known lithospheric plates: the Eurasian and North American plates in the northeastern and arctic regions, as well as the Eurasian and Amur plates – in the southern areas of Yakutia. The epicentral fields traced individual relief lineaments and identified active boundary structures combined into two large-scale seismic belts – BaikalStanovoy and Arctic-Asian. Their outlines are seen as bands of earthquake epicenters, elongated from the Olekma River to the Sea of Okhotsk in the south and as ensembles of separate groups and chains of earthquakes between the Laptev and Okhotsk Seas in the northeast and in the Arctic. Significant seismic activity has been detected in the northeast of the region – in the Olekminsk region and the Aldan Highlands (South Yakutia), as well as in the Yano-Oymyakon Highlands, the Chersky Ridge and the Laptev Sea. A map of epicenters was constructed for the entire territory of the region, where 12 districts were identified and an analysis of the seismotectonic situation in each of them was given. The map of Arctic earthquakes in the Lena River delta is considered separately. It is compiled according to the processing of digital seismograms obtained at 25 autonomous field stations installed in accordance with the Russian-German project "Seismicity and Neotectonics of the Laptev Sea Region" (SIOLA). In this area during 2016–2019 more than 2 thousand shocks of small energy classes KR≥7.2–10.7 (M≥1.8–3.7) were recorded within the depth interval of 1–36 km of the Earth's crust. The characteristics of the most seismically active local tectonic structures developed in this region are given.