Analysis of the stress field in a lacustrine sequence of eastern Precordillera, San Juan-Mendoza

Abstract

An analysis of faults affecting Late Neogene lacustrine deposits was made in Acequión area, placed in the south of the province of San Juan. These faults are associated with liquefaction structures and rock avalanche deposits originated by paleoearthquakes, extending the earthquake records until the early Holocene in this region. By comparing the present regional stress field (determined by instrumental seismicity, with the focal mechanism analysis of recent earthquakes occurred in the region) with the local stress field, it was observed that whereas the first one is characterized by compression, the local field on the lacustrine sequence is normal. The current regional stress field is compressive due to the subduction of Nazca plate under South America plate. The old lake embedded to Pedernal and Los Pozos range, is affected by normal faults, mainly due to a normal local stress originated by the arrangement of these deposits.