Seismo Lab Seminar

Caldera collapse eruptions are among the most destructive forces in nature. Yet, we have very little knowledge regarding their dynamics at the time scales of seconds to minutes. Rare seismic observations of caldera collapses at silicic volcanoes suggest that large earthquakes accompany these eruptions. The key question is, how do these earthquakes couple with the dynamics of the eruptions?

A window into these coupled dynamics comes from the more frequently observed caldera collapse eruptions at basaltic volcanoes. A defining feature of these eruptions are the episodic, Mw > 5 collapse earthquakes. These collapse earthquakes display puzzling characteristics defying conventional understanding of earthquakes: they do not obey scaling laws of rupture duration and magnitudes for tectonic earthquakes.

Up until recently, efforts to understand these earthquakes were hampered by the lack of a self-consistent model accounting for the earthquake-magma reservoir coupling.

I will present the first model that simultaneously explains seismic observations (at Kīlauea volcano in 2018) of earthquake nucleation, rupture propagation on the ring fault, and subsequent coupling between the caldera block and the underlying magma reservoir. Next, I will examine the role of magma viscoelasticity in controlling the dynamics of collapse. High viscosity of magma results in the development of boundary-layer flow near the chamber walls, which can significantly reduce the magnitude of collapse earthquakes. Lastly, I will demonstrate that, observations of meter-per-day fault creep in between the collapse earthquakes, accompanied by tens of thousands of micro-seismicity, reveal the spatial heterogeneity of friction on the ring fault