Los flujos piroclásticos del Volcán de Colima, México

Abstract

Several pyroclastic flow producing eruptions have occurred at Colima Volcano which include the 1611, 1818 and 1913 eruptions. Flows followed topographic lows to the south. The measured sections and maps of the volcano are presented. Grain size analyses showed Md varied from -1 to 3 and comparison showed similarity with intermediate pyroclastic flows. Flows contain abundant lithic fragments in a fine grained matrix and can be separated in flow units of 2 to 10 m which represent surges and avalanches. Chaotic, unstratified and unsorted pyroclastic flows are also present. Based on these characteristics we favor a dome collapse origen for the flows against the St. Vincent and Merapi types. The high degree of fluidity and high temperature of the flows is inferred from the charcoal present, bubble pipes and elongated lithic lenses. A mafic alkaline sequen ce was found interbedded with the andesitic pyroclastic flows which reflects the complex magmatic origen.