Crimean-Black Sea Region

Abstract

In 2014, the seismic monitoring of the Crimean Black Sea region was carried out by eight digital seismic stations located on the Crimean peninsula. For the entire territory of the region, earthquakes with Kmin=9 are representative. In 2014, 119 local earthquakes of КП energy classes in the range of 4.3÷11.2 were recorded, most of them have energy classes less than the representative energy level. The total number of earthquakes that occurred in 2014 is almost twice as large, and the total released seismic energy is 4.4 times less than the average values of ΣE for the period 2004–2013. The strongest earthquake of the year with КП=11.2, Mw=4.12 occurred on March 2 at 03h34m with depth of 28 km in the focal zone of the destructive Crimean earthquake of September 11, 1927, in the Yalta region. It was felt on the southern coast of Crimea with the intensity of I=2–3. The focal mechanism of both earthquakes (09/11/1927 and 03/02/2014) is similar: faults-shear with a predominance of the discharge slip. The main shock was preceded by six forshocks with a КП=6.5–8.0 and a depth of h=18–27 km. The energy level between the main shock and the strongest foreshock was 3 orders of magnitude (ΔКП=3.2), and between the strongest aftershock – about one and a half orders of magnitude (ΔКП aft=1.5). The activation of the central zone, including at the expense of aftershocks of the earthquake on March 2, was traced until the end of the year. At the same time, seismic energy was released unevenly: separately and in groups with some migration of foci and varying depth. In the focus of the earthquake on October 18 with a КП=10.1, Mw=3.8 (of the Black Sea Basin region), a strike-slip occurred under the action of sublatitudinal compression and submeridional extension. The time course for the last 10 years of release of the total energy of earthquakes proportional to the removed elastic deformation (Benioff graphs) is considered. Two relatively «calm» stages of deformation are noted: 2004–2007, at the speed of V1=4.45•107 Joules/year and 2009–2012 – V2=5.1‧107 Joules/year. Each of these stages ended with an increased discharge of accumulated deformations. It is concluded that the seismic situation in the region remains potentially dangerous for the next 2–3 years.