Abstract

The 2018 eruption of Kilauea volcano in Hawaii was unique in several ways. One of the interesting aspects was the well recorded incremental collapse of the summit caldera over the course of three months. This collapse was accompanied by over 50,000 earthquakes. These earthquakes tell an interesting story in themselves, but we are using them to measure seismic anisotropy using shear wave splitting at a spatial and temporal resolution that has not been achieved at volcanoes before. Preliminary results suggest that cracking of ring faults associated with the caldera collapse can be detected using shear wave splitting, and hence the timing and evolution of the deformation can be mapped in this way.

Seismic anisotropy is also affected by evolving stress and migrating fluids. Here, we use the unprecedented seismicity to complete the picture of seismic anisotropy in the Lower East Rift Zone (where it has not been imaged previously), investigate the transfer of stress between the propagating intrusion and the M6.9 earthquake that occurred concurrently on the décollement, and how stress and fluids affected the start and end of the eruption.