Active tectonics and first paleoseismological results in Faial, Pico and S. Jorge islands (Azores, Portugal)

dThe neotectonics of the islands of Faial, Pico and S. Jorge (Azores) is presented. Preliminary paleoseismology data from trench exposures across three active fault zones (Lomba do Meio, Lagoa do Capit (a) over tildeo and Pico do Carv (a) over tildeo faults) complement the information. Radiocarbon age constraints of pateoearthquakes suggest clustering of surface rupturing events. Slip rates deduced from paleoseismology analysis range from 0.10 to 0.40 cm/year and validate long-term slip rates obtained by neotectonic studies (using Pleistocene markers). The studied faults allowed a preliminary seismic hazard assessment: magnitudes of the largest pateoearthquakes, determined from slip per event range from M-w = 6.9 to 7. 1, and maximum expected magnitudes, estimated from rupture length or rupture area, vary from M-w = 6.4 to 6.8. The former M-w estimates are in closer agreement with the magnitude of the major historic and instrumental seismic events in the archipelago, even though the used empirical relations between magnitude and rupture parameters may not be the most adequate due to the unique tectonic setting of Azores.