Tectonic and seismic implications of an intersegment rupture The damaging May 11th 2011 Mw 5.2 Lorca, Spain, earthquake

Abstract

On May 11th 2011, a Mw 5.2 earthquake stroke the city of Lorca in the SE Spain. This event caused 9 fatalities, 300 injuries and serious damage on the city and the surrounding areas. The Lorca earthquake occurred in the vicinity of a region bounding two well-known segments of a large active fault, the Alhama de Murcia fault (AMF). The Lorca earthquake offers a unique opportunity to study how strain is accommodated in an intersegment region of a large strike slip fault. We map recent tectonic structures in the epicentral region and we use radar interferometry to analyze the coseismic deformation. Combining these data with seismological observations of Lorca seismic sequence we first model the source of the earthquake. Then we analyze the influence of our preferred model in the adjacent segments by Coulomb failure stress modeling. The proposed earthquake source model suggests that this event ruptured an area of ~4×3 km within the complex structure that limits the Goñar–Lorca and Lorca–Totana segments of the AMF. The induced static stress change on the adjacent segments of the fault represents a seismic cycle advance equivalent to 200 to 1000 years of tectonic loading.