Geologic mapping of the Colima volcanic complex (Mexico) and implications for hazard assessment

During the past 15 yr, volcanological studies in Mexico have been mostly focused on the pyroclastic stratigraphy and petrologic evolution of the volcanoes, with very little attention paid to detailed mapping of volcanic areas. In this study, we present a geologic map of the Colima volcanic complex, which covers approximately 3780 km (super 2) . The Colima volcanic complex is made of El Cantaro, Nevado de Colima, Paleofuego, and Colima volcanoes, totaling 422 km (super 3) in volume. The activity of the Colima volcanic complex started at El Cantaro with the emission of lava flows and domes ca. 1.7 Ma. About 0.53 Ma, 15 km southward, the formation of Nevado began with the emission of lava flows. Nevado produced at least four collapses that generated debris avalanches, debris flows, and pyroclastic-flow deposits. During late Pleistocene (>>38,500 yr B.P.), the formation of Paleofuego began 5 km further south with the emission of lava flows. Paleofuego collapsed at least five times, producing debris avalanches and pyroclastic-flow deposits. The last collapse of Paleofuego, at 2505 yr B.P., produced a 5-km-wide caldera, inside of which grew Colima volcano. Colima is the most active volcano in Mexico, with 45 eruptions during the past 426 yr, representing a potential hazard for the surrounding population of approximately 0.9 million people. From the geological mapping, it is clear that volcanic activity and collapses of the Colima volcanic complex have been controlled by the active Tamazula fault, which generated the NE-SW Alceseca-Atenquique graben.