SEISMICITY of the NORTH-EAST of RUSSIA in 2015

Abstract

The results of seismic monitoring of the Magadan oblast, the Chukotka Autonomous okrug, and the shelves of the adjacent seas (Okhotsk, Chukchi, Bering, and East Siberian seas) are considered. There were 14 seismic stations working in the region. The new station “Gadlya” was opened on the Okhotsk sea coast. The catalog includes information about 290 earthquakes with energy classes KR=4.4–12.6. As usual, most of them (93 %) are localized in the Kolyma region. The total seismic energy released within the region’s borders was ΣЕ=4.6341012 J. According to the earthquake energy completeness map Кmin built for the region, minimal energy level of earthquakes, Кmin=5.0, is provided at two areas near the Susuman and Magadan stations. The station network can register without omissions the earthquakes with Kmin≥8 at the Okhotsk sea and Kolyma areas, with Kmin≥10.6 in the Chukotka area. In 2015 three earthquakes with intensities I=2–4 by MSK-64 scale were felt in settlements of North East of Russia. The 2015 strongest earthquake occurred on June 1 at 10h53m with KR=12.6 (MPSP=4.9), h=31 km in the Kolyma area. A maximum shaking intensity of I=4 was observed in Omsukchan settlement (∆=132 km). In March 2015 a swarm of 29 weak earthquakes with KR=6.2–9.8 occurred northeast of Talaya settlement. Epicenters of Kolyma area earthquakes were plotted on the tectonic zoning map of the Magadan region. Most earthquakes are confined to the main deep faults oriented in the northeastern and sublatitudinal directions. All hypocenters are located within the Earth's crust. The seismicity level of the North-East of Russia in 2015 according to the “SOUS09” scale was assessed as "background average" for the observation period from 1968 to 2015. Spatially, all earthquakes in the North-East of Russia are traditionally concentrated within the major seismogenic belts – Chersky, North-Okhotsk, and Trans-Beringian.