Seismic scenario including site-effect determination in Torreperogil and Sabiote, Jaén (Spain), after the 2013 earthquake sequence

Abstract The recent seismic activity recorded in Jaén province in the south-east Iberian Peninsula has triggered great alarm among the people of the towns of Torreperogil and Sabiote despite the low magnitude of the events. The main objective of this paper is to examine why these low-magnitude event...
Ausführliche Beschreibung

Abstract The recent seismic activity recorded in Jaén province in the south-east Iberian Peninsula has triggered great alarm among the people of the towns of Torreperogil and Sabiote despite the low magnitude of the events. The main objective of this paper is to examine why these low-magnitude events are responsible for such a high degree of concern in this area of low seismicity. Of all possible explanations, including directivity effects and local geology, we found that the site effect was the most important candidate for clarifying this phenomenon. An earthquake scenario was considered for the maximum 5.2 Mw shock that could occur in the event of the rupture of the identified responsible blind fault. In order to simulate the strong motion derived from such as extreme event, a stochastic finite-fault simulation was generated using the standard values of the different media parameters for the region and a stress drop of 130 bar, deduced from the simulation of the greatest shock of the sequence. In order to include the site effect, which was considered to be very important in this study, a local survey using refraction micro-tremor (ReMi) techniques was performed in both towns (at 33 and 35 sites in Torreperogil and Sabiote, respectively) to determine the Vs30 values. The site response results obtained were taken into account in the simulation process, and the results are shown on peak ground acceleration (PGA) and peak ground velocity (PGV) contour maps for each town, with 200–500 cm/$ s^{2} $ as PGA extreme values. A map of intensities obtained from the PGV map is also shown; for the extreme event, macroseismic EMS98 intensities in the range of V–VII were obtained for those towns. The deterministic earthquake scenario developed here will be of great interest in planning civil defence responses in the event of an earthquake emergency and in regional development. Ausführliche Beschreibung