STUDY OF THE 2ND DECEMBER 2002 VARTHOLOMIO EARTHQUAKE (WESTERN PELOPONNESE) M5.5 AFTERSHOCK SEQUENCE

On the 2 December 2002 an earthquake (Mw=5.5) occurred near the city of Vartholomio (western Greece) causing damage in more than 1000 buildings. The University of Patras Seismological Laboratory permanent network stations recorded the mainshock and the aftershocks. Furthermore, twenty-six sites were instrumented to study the aftershock sequence. We identified more than 500 aftershocks with Md ranging from 2.0 to 4.3 during the first 30 days following the mainshock. The spatial and temporal evolution of the aftershock sequence is presented. We use the 370 earthquakes recorded at a minimum of 20 stations, with RMS less than 0.1 s and uncertainties less than 1 km, to infer the precise distribution of the seismicity in the fault region. The mainshock moment tensor inversion results are used in parallel to the aftershock sequence distribution in order to identify the causative fault. The results suggest a strike slip fault with dextral movement, which is trending NNE-SSW and fits the regional tectonics.