SEISMICITY of the BAIKAL REGION and TRANSBAIKALIA in 2018–2019

Abstract

We considered a character of the seismic process in the Baikal region and Transbaikalia in 2018–2019. During this time period, 14545 earthquakes with КR≥5.6 were registered. More than 94 % of the seismic events were localized in the Baikal rift zone. Within it, relatively strong earthquakes occurred in Khubsugul-Tunka area (March 29, 2019, Mw=4.8) and in the junction zone of the northeastern flank of the Baikal rift and the Olekma-Stanovoy orogenic system (September 28, 2019, Mw=5.1). 49 earthquakes caused felt macroseismic effects which most often manifested themselves in the settlements of the region with intensity of 3–4 and 4. Intensity of 5–6 was observed in few cases. Earthquake source parameters were determined for 81 seismic events with КR≥9.1. Most of them occurred in the seismotectonic regime of subhorizontal extension. 61 focal mechanisms were determined from P-wave first-motion polarities. Source parameters for 13 earthquakes were estimated using a joint inversion of P-wave first-motion polarities and surface wave amplitude spectra. In general, 2018–2019 are characterized by a moderate level of seismic activity.