Geophysical and geochemical precursors to changes in activity at Poás Volcano

Abstract

Acidic crater lakes at persistently active volcanoes act as both a moderator and an index of volcanic processes. Poás exhibits cyclic behavior characterized by calm periods alternating with periods of phreatic eruptions that last 2–10 years, which roughly correspond to liquid or vapor dominance. However, what causes the system to move on from one phase to the other remains unclear. By integrating the insights gained from different methods of monitoring, a view of the physical and chemical changes occurring before, during and after alterations in activity can be gleaned.