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Inter-Seismic Slip in Caldera Collapse Earthquake Cycles

Description: 

In most tectonic settings, multiple complete characteristic earthquake cycles have not been observed and loading histories can be complicated, which limits the extent to which field-scale fault frictional behavior can be resolved. Empirical rate-and-state dependent friction formulations based on small-scale lab experiments are a standard starting point, and there is experimental and observational evidence for the importance of processes such as dynamic weakening. However, the relevant physical mechanisms and potentially heterogeneous parameters controlling friction are generally not well constrained. In this work, we approach field-scale fault mechanics by studying caldera collapse at basaltic volcanoes, which has been observed to occur via sequences of multiple discrete ring fault earthquakes. We focus specifically on the well-monitored 2018 eruption of Kīlauea Volcano, which exhibited large amounts of both co- and inter-seismic slip. We use 2D axisymmetric earthquake cycle simulations, with fully dynamic elasticity and compressible viscous fluid flow, which show that standard rate-and-state friction formulations cannot readily produce the amount of co- and inter-seismic slip observed. We investigate whether adding dynamic weakening and asperities to primarily velocity-strengthening faults can better explain seismic and geodetic data. Additionally, we explore what depth-dependent fault properties and physical weakening mechanisms (e.g., thermal pressurization or shear heating) are most consistent with observations. These findings have implications for understanding fault mechanics in general, fault properties in volcanic and geothermal settings, and the dynamics of collapse eruptions.

Session: Learning Across Geological, Geophysical & Model-Derived Observations to Constrain Earthquake Behavior - II

Type: Oral

Date: 5/1/2024

Presentation Time: 10:30 AM (local time)

Presenting Author: Josh

Student Presenter: No

Invited Presentation: 

Authors