Source parameters of theM_W= 6.1 1910 Adra earthquake (southern Spain)

Abstract

SUMMARY We examine and model analogue recordings from 6 early mechanical seismographs for the 1910 June 16 earthquake at Adra, Southern Spain. Modern standard, time‐domain analysis techniques were applied to the historical data to estimate the source parameters of the event: The regional sparse network data were inverted for the deviatoric seismic moment tensor. The best moment tensor solution corresponds to a M0= 1.50 · 1018 Nm, MW 6.1 oblique strike‐slip event at 16 km depth. Our preferred faulting solution is: strike 122°, dip 80°, rake −137°, in very good agreement with available neo‐ and seismotectonic data. The source time function of this earthquake was estimated by deconvolving recordings of a MW 5.5 aftershock that occurred the same day. The time function indicates a total rupture time of 4.5 s, corresponding to estimates for mainshock rupture length of 12 km, and stress drop of 29 bar.

Geomorphic evidence of active tectonics in the Sierra Alhamilla (eastern Betics, SE Spain)

“…2; Martίnez-Martίnez and Azañón, 1997;Martinez-Diaz and Hernandez-Enrile, 2004;MarinLechado et al, 2005;Pedrera et al, 2006;Sanz de Galdeano et al, 2010). These faults generally dip to the SW and sometimes show evidence of synsedimentary activity and, moreover, produce seismicity in nearby areas where extensional focal mechanisms have been determined, for example, the Mw 4.8 2002 Gergal earthquake (Bejar et al, 2006) or the Mw 6.1 1910 Adra earthquake (Stich et al, 2003b).…”

Near-real-time Seismic Moment-tensor Determination in Spain

“…The Instituto Andaluz de Geoffsica y Prevenci6n de Desastres Sfsmicos (IAGPDS) determined the SMT of earthquakes in the Iberian-Maghrebi area between 1984 and November 2003 (Stich et al, 2003a). Buforn and Coca (2002) used P waves recorded on the short-period stations of the National Seismic Network of the Instituto Geogrfifico Nacional (IGN) of Spain to calculate the SMT of four intermediate-depth earthquakes that occurred in the southern Iberian Peninsula between 1987and 1992. Stich et al (2003b calculated the SMT of the 1910 Adra earthquake with recordings obtained from the recovery and digitization of old smoked records from five stations in a distance range from 375 to 1,843 km.…”

Moment Tensor Inversion for the 5 July 1930 Montilla Earthquake (Southern Spain)

“…Gray beach balls correspond to inversion of modern broadband waveforms. Black beach balls are those obtained from digitization and inversion of old analog records (Stich, Batlló, et al 2003;Stich et al 2005;Batlló, Stich, Palombo et al 2008). …”

“…A less routine effort is source parameter retrieval from analog records for Iberia-Maghreb earthquakes that predate the era of digital seismogram recordings in order to supply faulting parameters and seismic moment for those historic earthquakes, particularly relevant for seismic hazard and/or seismotectonic studies (Pondrelli et al 1999;Stich, Batlló et al 2003;Stich et al 2005;Batlló, Stich, Palombo et al 2008). …”