Characterizing and modeling the Onset of recurrent PHREatic eruptions (COPHRE) – COPHRE

Phreatic eruptions are small but dangerous events that occur with limited unrest and little warning. They can eject bombs and ash, and even give rise to pyroclastic density flows. Despite the increasing awareness of the high risk associated with phreatic eruptions, a knowledge gap exists regarding the processes that lead to them. Several hypotheses have been proposed to explain them, including a seasonal modulation due to rain infiltration, changes in the hydrothermal system, and/or input from the magmatic system at depth. The lack of knowledge results in significant uncertainty when anticipating phreatic eruptions, and assessing whether an ongoing phreatic eruption will evolve to larger phreato-magmatic and/or magmatic events.

The project COPHRE aims at addressing this knowledge gap. We will integrate a series of complementary studies of phreatic eruptions, including numerical simulations of the hydrothermal dynamics in the system, imaging the internal structure of shallower parts of a volcanic edifice, and collecting and analyzing petrological data on recent eruptions. Copahue volcano is one of the most active volcanoes in Patagonia and has been experiencing recurrent phreatic eruptions for the past few years. Because of its activity and the communities located nearby, it carries the highest volcanic risk out of 39 active volcanoes in Argentina. The ongoing recurrent phreatic activity and the priority of monitoring make this volcano an ideal case for our investigations. An improved understanding of the fundamental processes that drive phreatic eruptions could be used to mitigate their hazards at this volcano, and similar ones around the world (e.g. La Soufrière de Guadeloupe).