What can we learn from progressive rock failure in volcanoes?

Volcanic eruptions are often preceded by intense deformation and volcano-tectonic microearthquakes, which evidence the progressive failure of the volcanic edifice. Studying this process may be of interest for the more general understanding of the progressive failure of rocks.

Active volcanoes are pressurized by fluids and undergo considerable deformation prior to eruption. Surface deformation and seismicity are recorded continuously by volcanological observatory networks; both are due to the action of fluid pressure and rock weakening with deformation, and can be used to quantify fluid pressure variations and rock damage. In this talk we will show how coupling a simple fluid pressurization model with a seismicity-based damage model can be used to explain the surface deformations recorded on basaltic volcanoes. In particular, we will describe the foundations of the damage model. We'll show how damage, crack interaction and stress diffusion can explain the inverse Omori law often evidenced before eruptions, and the relationship between this law and entropy production during progressive rock failure. Finally, using a dataset from 24 pre-eruptive periods at Piton de la Fournaise, we’ll show how these concepts can be used to track the temporal evolution of the state variables that can help describe pre-eruptive processes.