Geological Hazard in the Department of Pocito, San Juan Province, Argentina
by
Laura P. Perucca
CONICET, Gabinete de Neotectónica, INGEO, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina

Following a comprehensive study of the hazards of geological origin affecting the Department of Pocito (located 5 kilometers south-west of San Juan city), it has been detected that the two most important ones are the seismic and alluvial fan flooding hazards.

An analysis of the seismic hazard and vulnerability in Pocito department is performed. The investigation is first focused on the evaluation of how the singular buildings and life lines of the urban zones are distributed and also on the characterization of La Rinconada fault zone location as a seismogenic source.

A great percentage of adobe buildings exists in Pocito, especially in the proximities of the epicenter of the 1952 earthquake of ML=7.0 associated to Precordillera oriental Faulting System.

Alluvial fan flooding hazard is too analyzed by considering it the most important hazard in regards to the frequency of the occurrence of the events.

The waters of the torrential rains that are common to the summer months, by the time they reach a dry riverbed, are already carrying a great load of solid material. These floods are usually short-lived and violent, reaching relatively high transport speeds.

Large quantities of solid material such a sediments of various size ranges, uprooted vegetation and all sorts of debris are transported and later accumulated in the piedmont and floodplain of the Sierra Chica de Zonda range

Within the floodplain area, where the urban and rural areas are located, the majority of the historical records of floods have been confined to the location of two streets, both oriented parallel to the slope down from the piedmont. During most rainfalls these streets have been transformed into sort of natural riverbeds, influencing the path of the floods and limiting their damaging civil structures.

The development of a predictive and early warning system, combined with public education and structural corrective measures are thought to be the means to minimize earthquakes and alluvial fans floods risks in the region.

Keywords: earthquakes, faults, floods, Pocito, hazards

Palabras claves: terremotos, fallas, inundaciones, Pocito, peligos

Date received: November 18, 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-24.