Short chronological analysis of the 2007-2009 eruptive cycle and its nested cones formation at Llaima volcano

Resumen

The Llaima volcano (38°41’S / 71°43†²W) is one of the most active volcanoes of South America. In the present work we have combined direct field and sequential photography observation plus remote sensing of low cost, making possible to reconstruct its 2007-2009 eruptive cycle. Llaima volcano eruption began on January 1, 2008 at 18:11 local time, preceded by seismic and surface precursory activity. The onset of eruptive activity was followed by a second paroxysmal eruption occurred on April 2009, and the occurrence of Hawaiian, strombolian and phreatomagmatic reactivation pulses which edified a series of small nested scoriae and spatter cones inside the main crater of volcano. Their evolution was widely registered, defining with clarity two eruptive stages and nine eruptive phases. Several basaltic pahoehoe and AA lava flows descended from the main crater, producing glaciers melting and then lahars, which transported large-size blocks of ice and boulders. Also, pyroclastic flows and ash fall events where observed. This activity persisted until 2009 when finally ended. The record is very important to learn about Llaima eruptive behavior and could be used in population risk management.