Distribution and stratigraphy of deposits produced by diluted pyroclastic density currents of the 1982 eruption of El Chichón volcano, Chiapas, Mexico

Abstract

The March 29 to April 4, 1982 eruption of El Chichón volcano in southeastern Mexico was characterized by a complex interplay between magmatic and phreatomagmatic eruptive events, that were responsible for the generation of plinian columns and concentrated and diluted density currents. Revision of the stratigraphy indicates that the interaction between magma and hydrothermal acid water played an important role during the last phases of the eruption. Diluted density currents were widely dispersed, mainly to the eastern side of the volcano due to the particular topographic conditions in this area. The overall distribution of pyroclastic surge deposits reflects the dispersal of fallout deposits determined by the direction of tropospheric (ENE) winds at the time of the eruption. This observation suggests that near-ground winds were strong and blowing in the same direction as high altitude (<18 km) winds, thus enhancing the dispersion of the vanishing portions of the pyroclastic density currents.