Liquefaction phenomena associated to historic earthquakes in San Juan and Mendoza provinces, Argentina
by
Laura P. Perucca
CONICET, Gabinete de Neotectónica, INGEO, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina
Coauthors: Stella M. Moreiras (CONICET, IANIGLA-CRICYT,Mendoza, Argentina)

Mendoza and San Juan lack in a brief record of historic earthquakes, reason why is only known a tiny part of their seismic activity. In the region, historic material about seismic movements is scarce; oldest reports come from XVII century after Spanish conquest. They are some vague narrations about high magnitude earthquakes occurred in the past; as an ancient narrative mentioning that before 1561 a huge temblor similar to 1861 earthquake took placed frightening aborigines living on this land. Nevertheless, San Juan and Mendoza have suffered the ocurrence of at least nine destructive earthquakes along last 150 years (1861, 1894, 1903, 1917, 1920, 1927, 1929, 1944 and 1977). During these earthquakes liquefaction effects were among the most widespread and most spectacular results of seismic shake, moreover a large part of the damages was the result of subsurface soils liquefaction.

One of the particularities of all earthquakes mentioned above was the spectacular modification of land in areas very far from the earthquake epicenter. Many landslides and liquefaction phenomena took place, historical sources mentioned cracks, sand boils and water piping occurrence in the saturated soils without cohesion.

Liquefaction process was one of the characteristic of all the earthquakes occurred in the western valleys of central west part of the Argentinian territory; cracks, sand volcanoes and spills have been very abundant affecting an extension of more than 4,000 square kilometers. Damages caused by liquefaction included bearing capacity failures beneath of buildings and tanks, renting of buildings, highways, channels and fields by differential horizontal and vertical displacements. Liquefaction effects were almost restricted to the Holocene deposits of alluvial plain paleochannels and flood plain.

In summary, for minimizing earthquake risk in seismic regions of Argentina, it is indispensable the study of potential areas that could be affected by liquefaction process and their possible impact in densely populated cities.

Palabras claves: terremoto, licuefacción, peligro, fuentes sismogénicas, Mendoza y San Juan.

Key words: earthquake, liquefaction, hazard, seismogenic sources, Mendoza and San Juan.

Date received: November 18, 2004