SEISMICITY of KAMCHATKA and COMMANDERISLANDS in 2018–2019

Abstract

The seismicity review of Kamchatka and surrounding territories for 2018–2019 is given. In the Kamchatka earthquake catalogue, the minimum local magnitude of completeness is MLmin=3.8, and for the Kamchatka seismically active region (latitude = 50.5–56.5° N, longitude = 156.5–167° E) MLmin=3.7, and for earthquakes with h≥350 km under the Okhotsk sea MLmin=3.8. The Kamchatka earthquake catalogue for 2018–2019, published in the Appendix to this article, includes 3646 events with ML≥3.5; 228 earthquakes with ML=3.65–7.3 were felt in Kamchatka and surrounding areas with seismic intensity I of 1–2 to 6–7 according to the Seismic Intensity Scale-2017 (Russian state standard). For 134 events with ML≥5.0 that occurred in 2018–2019 within the area of responsibility of Кamchatka branch of Geophysical Survey RAS, an attempt to calculate the seismic moment tensor (SMT) was made. The SMT and depth h of the equivalent point source were calculated for 67 earthquakes in 2018 with a range of ML=5.0–7.3, and for 67 events in 2019 with a range of ML=5.0–6.45. The level of seismicity according to the "SOUS'09" scale in 2018 corresponded to the “background increased”, but within the assessment accuracy – “high”; for 2019 it was the “background average”. On December 20, 2018, there was a strong earthquake with Mw=7.3, named “the Angular Uplift earthquake”. This earthquake was the strongest intraplate event, which belongs to the region south of the junction zone of the Kamchatka and Aleutian trenches The earthquake was accompanied by a large number of aftershocks.