The seismicity review of Kamchatka and surrounding territories for 2014 is given. In Kamchatka earthquake catalogue minimum local magnitude of completeness is MLmin=3.5, and for earthquakes under the Okhotsk sea with h≥350 kmMLmin=3.6. The Kamchatka earthquake catalogue for 2014 with ML3.5, published in the Appendix to this annual, includes 1114 events. 86 earthquakes of the catalogue with ML=3.35–6.2 were felt in Kamchatka and surrounding areas with seismic intensity I ranged from 2 to 5 according the MSK-64 scale. For all events with ML5.0 occurred in the area of responsibility of the KB GS RAS in 2014, an attempt to calculate the seismic moment tensor (SMT) was made. There are 40 such events in the regional catalogue. For 36 earthquakes, the SMT and depth h of the equivalent point source were calculated successfully. The calcu-lations were performed for the SMT double-couple model using a nonlinear algorithm. In 2014, a typical location of the earthquake epicenters was observed in the Kamchatka zone. In 2014, the seismicity level in all selected zones and in the region as a whole corresponded to the background one according to the “SESL’09” scale. The number of recorded events with ML3.6 and strong earthquakes with ML5.1 is close to the average annual value. Anomalous and outstanding events were not recorded.
The February 28, 2013 earthquake (MwGCMT=6.8), which occurred on the southeast coast of Kamchatka, is discussed. The instrumental hypocenter location reported by the KB GS RAS is φ=50.67N, λ=157.77E, h=61 km. Three magnitudes were obtained: local magnitude ML=6.9, code-wave magnitude Mc=6.6, mo-ment magnitude Mw=6.7. The focal mechanisms of the February 28, 2013 earthquake and its aftershocks with ML≥6 correspond to the tectonic conditions of subhorizontal compression in the NW–SE direction. For most of these mechanisms, the shallow plane falls under Kamchatka, which corresponds to the geometry of the subduction zone. The small-focus aftershocks cloud of the February 28, 2013 earthquake has the 5828 km size and is extended in the north-east – south-west direction. The aftershock process has the three-phase character and can be considered as a stream of seismic events decreasing in time with three successive stages with different attenuation modes. The change in attenuation modes is associated with strong after-shocks. The duration of the decaying aftershock process is ~ 100 days. The February 28, 2013 earthquake was felt with intensity ranged from 2 to 5–6 on the MSK-64 scale in 33 localities (Δ=81–493 km). The mac-roseismic impact area was about 56∙103 km2. The mainshock and its four strong aftershocks have a similar picture of macroseismic manifestations: the macroseismic effect is larger on the east coast of Kamchatka; the strongest shakes has been observed in Severo-Kurilsk (Paramushir Island). The elongation of the isoseist along the Kamchatka eastern coast has been observed, which is typical for Kamchatka earthquakes. The strong ground motions from the February 28, 2008 earthquake has been recorded using the Kamchatka net-work of digital accelerographs. The level of peak amplitudes for this earthquake is consistent with average trends in the Kamchatka region. Attenuation parameters are typical for Kamchatka. The shallow layer of the seismic focal zone of the Kuriles and South Kamchatka, in which the February 28, 2013 earthquake was recorded, is one of the most active seismic areas in the North-West Pacific. Earthquakes with M>8 were re-peatedly occurred here, causing a tsunami and intensity of shakes up to 9 on the MSK-64 scale in the south of Kamchatka.
In this paper we present brief review of results of Kamchatka Seismic Monitoring and Earthquake Prediction System operations in the last five years. In addition, the retrospective of development of hardware, equipment and software of the System performed. The main direction in the System evolution in this period concerned the creation and modernization of data acquiring and pro-cessing methods. One of main results is creation basic informational space, that includes all pro-cesses if seismic observations, from data acquiring till exchange (including external users) of da-ta processing results. In particular, the system of data storage was deeply modernized, high-speed access to the data archive was provides, high-performance computing clusters were deployed, all seismic stations were combined in the unified network. Development algorithms and software for data processing and seismic regime controlling was continued. Creation and development of the Seismological Data Informational System (SDIS) provide the access to seismic observations re-sults for research community. The service of automatic data exchange with external users was created and incorporated in SDIS. Kamchatka Seismic Monitoring and Earthquake Prediction System in 2016-2020 allowed registering and processing over 83 thousand tectonic and volcanic earthquakes. The complex studies for seven the strongest ones were conducted. Detailed analysis showed, that magnitude of completeness for regional scale is MLc=2.5, and for local scale (for example – volcano seismic monitoring) – MLc=–0.2.
The seismicity review of Kamchatka and surrounding territories for 2015 is given. In the Kamchatka earthquake catalogue, the minimum local magnitude of completeness is MLmin=3.5, and for earthquakes with h≥350 km under the Okhotsk sea MLmin=3.6. The Kamchatka earthquake catalogue for 2015 with ML3.5, published in the Appendix to this issue, includes 1213 events. 92 earthquakes of the catalogue with ML=3.0–6.5 were felt in Kamchatka and surrounding areas with seismic intensity I=2–6 according to the MSK-64 scale. For all events with ML5.0 that occurred in 2015 in the KB GS RAS area of responsibility, an attempt to calculate the seismic moment tensor (SMT) was made. There are 32 such events in the regional catalogue. For 28 earthquakes the SMT and depth h of the equivalent point source were calculated successfully. The calculations were performed for the SMT double-couple model using a nonlinear algorithm. In 2015, a typical location of the earthquake epicenters was observed in the Kamchatka zone. In 2015, the seismicity level in all selected zones and in the region as a whole correspond to the background one according to the “SESL’09” scale. The number of recorded events with ML3.5 and strong earthquakes with ML5.0 is close to the average annual value. Anomalous and significant events were not recorded.
The seismicity review of Kamchatka and surrounding territories for 2016–2017 is given. In the Kamchatka earthquake catalogue, the minimum local magnitude of completeness is MLmin=4.0, and for earth-quakes with h≥350 km under the Okhotsk sea MLmin=4.3. The Kamchatka catalogue of earthquakes with ML=3.6–7.3 for 2016–2017, published in the Appendix to this article, includes 2898 events. 191 earthquakes of the catalogue were felt in Kamchatka and surrounding areas with seismic intensity I=2–6 according to the MSK-64 scale. For all events with ML≥5.0 that occurred in 2016–2017 within the area of responsibility of Kamchatka branch of Geophysical Survey RAS, an attempt to calculate the seismic moment tensor (SMT) was made. There are 109 such events in the regional catalogue. For 102 earthquakes the SMT and depth of the equivalent point source were calculated. The calculations were performed for the SMT double-couple model using a nonlinear algorithm. The level of seismicity according to the “SOUS'09” scale in 2016 corresponds to the “background increased”, for 2017 it is also the “background increased”, but within the assessment accuracy – “high”. In 2016–2017 within the Kamchatka branch area of responsibility, an atypical pattern of the location of earthquake epicenters was observed due to the occurrence of two strong events – the Near Aleutian (Mw=7.8, July 17, 2017) and South Ozernovsky (Mw=6.6, March 29, 2017) earthquakes and their aftershock processes.
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