Seismicity of Croatia in the period 2006-2015

Abstract

During the ten-year period from 2006 to 2015 a total of 36 733 earthquakes were located in Croatia and its surrounding areas, with 37 main events registering magnitudes from 4.0 to 4.9. Seismically the most active was the coastal part of Croatia confined to two seismically distinguished areas. The NW domain was seismically less active, with almost 10 000 located events (seven were of magnitude M_L ≥ 4.0), among which were the three strongest events that occurred in Croatia during the observed period. Two of them occurred in the Senj epicentral area, the first one on 5 February 2007 at 8:30 UTC (L = 4.9, I_max = VII °MSK) and the second one on 30 July 2013 at 12:58 UTC, (M_L = 4.8, I_max = VI °MSK). The third event occurred near Kornati Islands on 18 July 2007 at 10:54 UTC (M_L = 4.8). The SE domain experienced the highest number of earthquakes (over 19 000 located events, with 24 events of magnitude M_L ≥ 4.0, among which the strongest one was of magnitude M_L = 4.9 with the epicentre in Bosnia and Herzegovina near the Croatian border). The seismicity in the continental part of Croatia was weak-to-moderate, with earthquakes of magnitudes M_L ≤ 4.1. Focal mechanisms were obtained for 31 earthquakes with magnitudes M_L ≥ 4.0, and individual earthquakes have also been macroseismically analysed. Low current moment release rates for both regions (continental and coastal) as compared to long-term averages, indicate the regions are currently in the strain accumulation phase.