Seismically-induced landslides by a low-magnitude earthquake: The Mw 4.7 Ossa De Montiel event (central Spain)

The Ossa de Montiel (2015/02/23, Mw 4.7) earthquake struck the central part of Spain and was felt far from the epicenter (> 300 km). Even though ground shaking was slight (Imax = V, EMS-98 scale), the earthquake triggered many small rock falls, most at distances of 20–30 km from the epicenter, greater than previously recorded in S Spain (16 km) for earthquakes of similar magnitudes. The comparative analysis of available data for this event with records from other quakes of the Betic cordillera (S and SE Spain) seems to indicate a slower pattern of ground-motion attenuation in central Spain. This could explain why slope instabilities occurred at larger distances. Instability was more frequent, and occurred at larger distances, in road cuts than in natural slopes, implying that such slope types are highly susceptible to seismically induced landslides.

This work has been funded by Spanish Ministry of Economy and Competitiveness, research project CGL2011-30153-C02-02, and by the research groups RNM-374 (Junta de Andalucía), TECTAC (UCM-910368) and VIGROB-184 (Universidad de Alicante). Mr. Loffredo acknowledges funding of the Università di Roma — La Sapienza (post-graduate grant) (Concorso A N.480 - Area CUN 04).