Historic Earthquakes and the urban zone of Gran Mendoza. Mendoza. Argentina
by
Graciela E. Tello
Neotectonic and Geomorphology Research Team. Institute of Geology. University of San Juan. Argentina

The Gran Mendoza urban zone shows how the earthquakes have accompanied the evolution of the urban nucleus. The historic seismic event of April 22, 1782 produced an earthquake known a 'Santa Rita". Nevertheless, the greatest earthquake occurred on March 20, 1861, in the early evening (8:36 p.m.), in the area known as Cerro La Cal, causing the loss of more than 2,000 homes , at least 5,000 fatalities, and 1,000 injured persons. The testimonies of eyewitnesses all coincide on "having heard a tremendous deafening sound, as if produced by many cars rolling together over an arched terrain altogether, or as the simultaneous explosion of a battery of cannons". In this movement there was a sudden movement of the ground, the city literally swayed and almost all of the buildings collapsed.

Later, in 1985, another strong movement was registered, epicenter in an area known as Anticlinal Barrancas Lunlunta-Carrizal, which shook the capital of Mendoza. The worst affected areas were Godoy Cruz, Las Heras, and Maipu.

Considering the instrumental seismic registrations of NEIC, since 1973 to present time, it has been observed that the superficial seismic events (less that 30km) are concentrated to the west 68'30'longitude west. The areas most affected were Las Peñas, Capdevila -Borbollon, and La Cal. Meanwhile, the profound tremors (more than 30km) are concentrated towards the Cordillera area.

These recordings signal that the area north of Mendoza is characteristically vulnerable considering its seismolgical, tectonic, hydraulic, and building features , which, in the event of major seismic activity, and could cause the superficial rupture and/or the destruction of populated areas.

The evaluation of the siesmic-risk to the area, leads to the following inferences as regards to the macro-seismic zoning for Gran Mendoza. The results obtained indicate the Capital to be at very high-risk, Godoy Cruz at high-risk, Las Heras-Guaymallen, at moderate-risk, and Lujan de Cuyo-Maipu at low-risk.

Date received: November 19, 2004

Copyright © 2004 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caod-37.