On September 13, 2020, an earthquake with a magnitude of Mw = 4.8 occurred in the Uglegorsk district of the Sakhalin region. Residents of the localities nearest to the epicenter felt it with a force of up to 5 points on the MSK-64 scale. A total of 62 aftershocks were recorded. The seismic process lasted for about two days, the major mass of aftershocks was registered during the first 7 hours. The epicenters of the registered earthquakes are confined to the system of the regional West Sakhalin fault. However, the fact of active mining of brown coal at the Solntsevskii quarry and massive blasting in the epicentral zone of the Uglegorsk earthquake does not exclude the relation between the seismic process and technogenic seismicity. The article presents the results of observations of the seismic process in the epicentral zone of the Uglegorsk earthquake in September 2020 and considers the probable causes of its occurrence.

On November 25, 2013, at 03:23 UTC, an earthquake with a magnitude of МwGCMT=5.2 was recorded in the Laperuz Strait water area. This earthquake was the strongest in the south of Sakhalin Island in 2013. Parameters of the earthquake have been determined by data of seismic stations of the regional network of GS RAS Sa-khalin branch, seismic stations of global network IRIS (GSN) and Hokkaido University. Earthquake parameters on data of regional network are in accordance with data of the international seismological centers. The intensity of concussions in some areas of Sakhalin was 4–5 points on a scale of MSK-64 and 3 points on the JMA scale on the island of Hokkaido. The focus shift has happened under conditions of close horizontal compression, seismodislocation type – uplift. The earthquake of 2013 has arisen in the place of regional tec-tonic structures contact – breaks of West Sakhalin and Central Sakhalin. The seismic model was described by data of local network of field stations. Results of observations of an earthquake on November 25, 2013 are written in this article.

On April 23, 2017 at 06h 37m UTC, an earthquake with a magnitude of Mw=5.1 was registered in the foothills of the Yuzhno-Kamyshovy Ridge of the Krillon Peninsula. This earthquake was the strongest on Sakhalin Island in 2017. The earthquake parameters were determined according to the data of the Sakhalin branch of the Geophysical Survey RAS regional network with the use of data from the global IRIS Network (GSN) and stations of Hokkaido University. The obtained earthquake parameters according to the regional network are consistent with the data of international seismological centers. The maximum intensity of shaking from the earthquake on April 23, 2017 in the settlements of Southern Sakhalin was I=4 on the MSK-64 scale, on the Hokkaido Island – I=II on the JMA scale. The displacement in the earthquake foci was realized under conditions of near-horizontal sublatitudinal compression. The type of seismic dislocation is a reverse fault. The use of data from the seismic stations of the local network of Southern Sakhalin allowed analyzing the seismic regime in the epicentral zone of the Krillon earthquake.

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