Geodynamics of Azores-Tunisia

The following four papers deal with the seismicity and seismotectonic of the region. Carrilho et al. present the first results of GEOALGAR, a project initiated in 2000 to monitor the seismic activity in the Algarve region (southern Portugal). In this paper results of the relocation of epicenters and determination of fault plane solutions are presented. The new epicentral locations show a more organized spatial distribution which could indicate a possible correlation with some known tectonic features. Fault plane solutions are predominantly of strike-slip motion consistent with a horizontal compression in the NW-SE to NNW-SSE direction. The paper by Yelles-Chaouche et al. presents a detailed study of the 22 December, 1999 earthquake at Ain Temouchent (northwest Algeria) of magnitude 5. 7. The earthquake caused serious damage in the town of Ain Teemouchent with 25 casualties and 25000 people left homeless. Intensity map, surface features and the focal mechanism, based on wave form analysis, are shown. The mechanism corresponds to reverse fault motion with planes striking NNE-SSW resulting from horizontal compression in the NW-SE direction. This corresponds to the general mechanism found for Algeria earthquakes. Buforn et al. present a study of the characteristics of the plate boundary between Africa and Iberia, from west of Cape San Vicente to Algeria, using seismicity and source mechanism data. The region is divided into three areas which manifest different characteristics.