The Berkovići (BA) 22 April 2022 earthquake sequence – seismological and seismotectonic analysis

<p>A strong earthquake, <em>M_L</em> = 6.0 (<em>M_W</em> = 5.7), occurred on 22 April 2022 at 21:07 UTC with an epicentre near Berkovi&#263;i in Bosnia and Herzegovina, with focal depth of about 20 km. The earthquake was felt throughout Bosnia and Herzegovina, Montenegro, Croatia (especially Dalmatia), but also in Slovenia, Italy (especially the western coast of the Adriatic), Serbia, Albania and North Macedonia. The maximum intensity of the earthquake was rated as VII&#8211;VIII EMS in Berkovi&#263;i and Ljubinje. A young woman in Stolac lost her life from a rock slide caused by the earthquake. In the wider epicentral area the earthquake caused a number of large or small rock falls, many chimneys were damaged, tiles fell from the roofs, plaster fell off, and there were also large cracks in the walls.</p> <p>By 31 October 2022, the DuFAULT project researchers located 6220 aftershocks (39 with <em>M_L </em>&#8805; 3.0), with as many as 900 located in the first 12 h of the series. The strongest aftershock, <em>M_L</em> = 4.9, occurred on 24 April 2022 at 4:27 UTC with focus at a depth of about 25 km and the epicentre also close to Berkovi&#263;i. The vast majority of earthquakes have their foci relatively deep for this area, at depths between 15 and 28 km. Most of the epicentres form a compact group slightly elongated parallel to the NW-SE Dinaric strike, however two smaller groups northwest and southeast of the main group stand out with extension perpendicular to the Dinaric strike with somewhat shallower foci. The analysis of the focal mechanism and the hypocentral spatial distribution suggest that the mainshock resulted from the NE-SW directed compression and occurred on a reverse fault, on a moderately NE-dipping plane. Interestingly though, this series is also characterized by earthquakes released by a tension along the NE-SW striking and approximately 45&#176; dipping normal faults, documented in the smaller north-western group.</p> <p>We will present spatio-temporal analysis of seismicity, resulting focal plane solutions and seismotectonic interpretation.</p>