Erupciones del volcán Nevado del Huila, en febrero y abril de 2007, y los cambios en su masa glaciar

Abstract

The volcano Nevado del Huila is located in southwest Colombia. lts behavior has been mostly effusive and predominately andesitic. Lava flows, domes and pyroclastic flows have been generated during its development. On February 18th and April 17th 2007, two phreatic eruptive events were registered. These events were associated with a 4 km high column of ash, formation of a N-S directed 2 km long fissure, change in the pre-existing glacial crack system, an ash fall that covered Pico Central, formation of a new 2-3 km long fissure that cut through the SW and NE slopes of the Pico Central, partial loss of El Oso Glacier (to the east) and the formation of two small lahars which were directed to the Paez and Simbola streams which affected important road infrastructure and left the local populations isolated. Presently, the morphological changes of glacial mass include gradual melting due to hot gases that emerge from permanent fumaroles along the two big fissures which formed recently, tilting and melting of ice-blocks near the edges of the big fissures and partial loss of some glacial tongue fronts. Previous studies of glacial retreat looked at the total loss of this glacial mass during the 1960's and 1970's without considering the accelerations due to volcanic eruptions and earthquakes. Therefore, these changes caused by the recent volcanic activity and its subsequent effects are generating a much faster glacial retreat which may lead to a faster retreat of this glacial mass.