Quaternary faulting in La Laja Zone, and its relation to the 1944 earthquake, Albardón Department, San Juan, Argentina

Abstract

San Juan city is located in the central western region of Argentine Republic, the most seismic zone of the country. The city was affected by a destructive earthquake in 1944 (Ms=7.4) that caused great economic losses and nearly 10,000 casualties.

Historical reports associate this earthquake with an active fault located nearly 25 km north of the city of San Juan, in La Laja zone, with a superficial rupture length of 8 km and a maximum verti- cal displacement of 0.60 m. Correlations of fault length and displacement with earthquake magnitude are utilized to assess the seismic hazard of the area. Subsequent studies demonstrate that these superficial rupture values do not agree with the obtained by applying empirical relationships widely used in the world for a Ms = 7.4.

In this work, we show evidences of superficial rupture in four faults located in La Laja area, which were probably reactivated during the 1944 earthquake and whose total superficial rupture lengths and maximum vertical displacement would coincide with expected values by applying the empirical relationships.