Volcano seismology

Seismic activity is one of the main precursors of volcanic eruptions. This activity, which is low during volcanic quiescence, can strongly increase in the months, weeks or days preceding eruptions. The study of volcanic seismicity is the basis of monitoring methods and eruption forecasting. Furthermore, the analysis of the various types of earthquake which occur inside volcanoes allow understanding better physical processes in magmatic and hydrothermal systems.

We develop specific methods for volcanic earthquakes studies which are based on spectral or autoregressive methods, seismic array processing, or precise source location. We aim at explaining in term of physical mechanisms both the seismic events associated with ruptures of solid rock and the vibrations related to the fluids (magma, water, gas) that fill cavities in the structure. Thus, we try to extract from seismic observations useful information in order to constrain models of magmatic processes.

Figure : 24 hours recording of the seismic activity of Colima volcano, Mexico, during 24 hours. Earthquakes are drawn in colors that depend on the type of event (red = explosion ; green = fluid related event ; etc.). This classification is carried out automatically using a voice recognition system adapted for volcano seismology (collaboration with University of Granada, Spain, and University of Colima, Mexico).

These researches are based on the analysis of records of seismic events and ambient noise from permanent monitoring networks or from temporary field experiments. Whenever possible, we interpret the seismic data together with other geophysical observations. The methods which are developed can be implemented in volcanological observatories where they improve volcano monitoring.

We mainly study the seismic activity of volcanoes in Latin America (Mexico, Costa Rica, Peru), in Indonesia (Merapi), and Piton de la Fournaise volcano (La Reunion Island).