Estudio de los depósitos volcánicos desde el Pleistoceno superior del volcán Sumaco, provincias de Napo y Orellana

Abstract

Sumaco volcano (3830 msnm) is characterized by a conical and very symmetrical main volcanic building with an approximate base of 20 km and with a slope of its high flanks of up to 30º inclination. In the present work the products of the volcano from the Upper Pleistocene until the recent one were identified. The products found have been studied petrographically, and several representative samples were collected to perform geochemical analyzes and thin sections. In total, four avalanche deposits were studied, three lava flows, a lahar deposit and two deposits of pyroclastic flows. It has been identified by studying four stratigraphic sections at least five layers of ash around the Sumaco volcano. The thickness of the layers and the size of the lithic ones suggest that the eruptions were with VEI between 3 and 4. A manual drilling carried out on the “Laguna Guagua Sumaco” allowed us to know the volcano experienced at least 6 small eruptions during the last 360 years. Confirming its recent activity with a last eruption approximately in 1660 AD, this allows it to be classified within the group of potentially active volcanoes of Ecuador.