Seismotectonics of the 1755 Meknes earthquake (Morocco)

Abstract

The November 1st, 1755 Lisbon earthquake has been largely studied, its source constrained to be a 200 long structure, its magnitude estimated around 8.7, and the stress regime argued as a NNW-SSE directed compression. Less well knoll is the Meknes earthquake, occurred a few days later in Morocco and considered the effect of a strong aftershock in Portugal. It had destructive effects in the Meknes region, along the E-W trending Rides Prérifaines, the main frontal thrust of the Rif. Historical data indicate an E-W elongation of the epicentral macroseismic area, where we surveyed the major recent faults. Historical descriptions of the earthquake indicate ground ruptures in two areas of the Rides Prérifaines. Field work and air photo interpretation allowed us to relate these ruptures with the local thrust front, so that they may be assumed to correspond to coseismic surface faulting of the Meknes earthquake