Source parameters of the 1992 Melilla (Spain, M-w=4.8), 1994 Alhoceima (Morocco, M-w=5.8), and 1994 Mascara (Algeria, M-w=5.7) earthquakes and seismotectonic implications

Source mechanisms of the Melilla, Alhoceima, and Mascara earthquakes, inclu ding fault-plane solutions, waveform modeling, and spectral analysis, are p resented. Strike-slip solutions have been obtained for the Melilla and Alho ceima earthquakes and reverse faulting for Mascara. Teleseismic P-wave inve rsion, using broadband data, show a complex mechanism for the Alhoceima ear thquake formed by two subevents at very shallow depth (7 and 8 km) and scal ar seismic moments of 1.1 x 10e + 17 N-m and 4.8 x 10e + 17 N-m. The Mascar a earthquake was a single event, with a shallow depth (4.5 km) and a scalar seismic moment of 3.3 x 10e + 17 N-m. Results of the Alhoceima, Melilla, a nd Mascara earthquakes, together with 53 focal mechanisms in the region, sh ow a regional stress regime that corresponds to horizontal compression in a NW-SE direction, associated with the convergence between Eurasia and Afric a. A change of the stress regime in the plate boundary of the Ibero-Maghreb ian region has been found.