Kamchatka and Commander Islands

Abstract

The seismicity of Kamchatka and surrounding territories for 2013 is viewed. The minimum local magnitude of completeness is MLmin=3.25 in the Kamchatka earthquake catalogue totally, and MLmin=4 for earthquakes under the Okhotsk sea (with h≥350 km). The Kamchatka earthquake catalogue of 2013 with ML≥3.6, which includes 1750 events, is published. 146 earthquakes of published catalog with ML=3.6–7.8 were felt with seismic intensity ranged from 2 to 7 of the MSK-64 scale in Kamchatka and surrounding areas. Focal mechanisms were determined in two ways: 1) from first motion P-wave arrivals for 107 earthquakes; 2) using waveforms for 25 earthquakes. The background seismicity level (SESL’09) within the Kamchatka responsibility zone was extremely high in 2013. It exceeded the rate of seismicity in all previous years of observations. There were 6672 earthquakes, including 129 events with КS≥11.5 (ML≥5) in the region during the year. The mechanisms of 107 earthquakes were defined. 148 earthquakes were felt with intensity from 2 up to 7 on the territory of Kamchatskii Krai, North Kuril Islands, and Komandor Islands. There were several unusual events in 2013. The strong earthquake with magnitude Mw=5.8 on March 13 in the area of the Kamchatka Isthmus (Il'pyr earthquake), which is a rare phenomenon for the Northern Kamchatka. There was the strongest deep earthquake in the world (Mw=8.3) on May 24 under the Sea of Okhotsk (Okhotsk earthquake) at the depth of 630 km. The event caused an abnormal macro-seismic effect. The intensive earthquake swarm was observed in the Avacha Bay (Mwmax=6.1) in May 2013. It is the strongest earthquake swarm registered by the Kamchatka network during the period of detailed seismological observations since 1962