Is Ël Niño" - ENSO Climatic Phenomenon influencing landslide occurrence in the Central Andes, Mendoza Province, Argentina?
by
Stella Maris Moreiras
Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA) - CRICYT. CONICET. Mendoza. ARGENTINA

ENSO climatic phenomenon has been widely referred around the world because of its devastating impacts. This event is associated with greater landslide occurrence, however in the Argentine Andes this had not been analysed.

In study area (32º S-69º W), El Niño-years are characterised by major precipitation events, as consequent landslides induced by summer rainstorms tend to be more frequently. The extraordinary storms of 1982-1983 and 1991-1992 produced a greater number of landslides in the region with inestimable damages.

Historical data on landslides triggered by rainfall during the last century (1902-2002) were statistically analysed. A greater number of landslides happened in warm episodes rather than cold episodes, moreover during La Niña the mean of landslide records was lower than it was in neutral years; however ANOVA revealed that there is no significant difference (p>0.05). This is probably related to the complexity of convective systems in the region influenced by the Pacific Anticyclone and the Atlantic Anticyclone.

Historical landslide information was statistical analysed, considering wet and dry periods influenced by Atlantic Anticyclone. More landslides happened during wet periods according mean values, but ANOVA showed no significant difference.

Distinguishing landslides happened in Cordillera Frontal and Precordillera, ANOVA showed significant differences during warm phase, and no significant differences during cold phase. Significant differences also exist during dry and wet periods. Moreover, the most persistent dry period that lasted 9 years from 1947 to 1955 recorded landslide events only in Cordillera Frontal.

According results, a greater landslide activity exits during warm episodes for the Cordillera Frontal, with less activity for cold episodes. Likewise more landslide activity is expected in Precordillera during wet period than during dry period. A future increase in landslide hazards should be taken into account in both geological provinces due climatic change.

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-19.