EAST-BLACK SEA EARTHQUAKE on December 23, 2012 with КР=14.1, Mwreg=6.0, MwGCMT=5.8, I0p=6-7 (Black Sea, Abkhazia)
The instrumental and macroseismic data on the East Black Sea earthquake on December 23, 2012 from КР=14.1, МwGCMT=5.8, which occurred in the Black Sea in 25-30 km from the coast of Abkhazia are given. This earthquake became the strongest in the southeastern part of the Black Sea for the entire historical and instrumental periods. Known historical earthquakes had smaller magnitudes. The area of the earthquake within the limits of tracking the continental structures to the shelf can be attributed to the Adler-Abkhaz regional structural-facies zone, and more specifically to the South Gudauta flexure zone. The earthquake is a unique large sequence of aftershocks. In 2012, 167 aftershocks with КР=5.2-13.0 were registered, the representative level was the Кmin=7.5. For a more accurate position of the hypocenter the double difference method is used. Estimations of errors in the coordinates of hypocenter aftershocks were: latitude δφ=1.6 km, longitude δλ=1.6 km, depth δh=2 km. The bulk of aftershocks occurred at depths of 7-15 km (h aver=11.4 km). The main shock and its strongest aftershock were located at depths of h=7±2 km and h=8±2 km. The «cloud» of the aftershocks is stretched to the northwest along one of the regional faults. The main shock and the strongest aftershocks are on the south-western flank of the region. According to the data of different centers, the mechanism of the focus of the main shock and the strongest earthquake aftershock was constructed as strike-slip type of motion in the source. The distribution of the number of aftershocks in time is complex and, perhaps, partly explained by the trigger character (23 % of aftershocks). The law of Bath on the relationship between the magnitudes of the main shock and the strongest aftershock is not fulfilled. The complexity of the aftershock field is confirmed by the bimodal distribution of the parameter of the amplitude ratio in the P- and S-waves ASmax/APmax and the instability of the slope of the repeatability curve at different time periods. The collected macroseismic data are represented on the points-balls map, but they did not allow the construction of an isolines map.