Understanding Summit Failure Processes During the 2018 Kilauea Eruption Through Analysis of Earthquake Swarms

Date: 4/26/2019

Time: 09:15 AM

Room: Puget Sound

In early May 2018, Kilauea’s summit lava lake began to quickly drain after a rift zone intrusion and subsequent collapse at the Pu’u ‘O’o vent, marking the start of a major eruption. As fissures opened and magma poured out in the Lower East Rift Zone, the summit crater began to collapse. Major summit collapse events occurred roughly every 1-2 days between May 16 (local time) and August 2 and were each preceded by swarms of earthquakes. The rate of earthquakes in each swarm increased leading up to the collapse events and dropped significantly after a collapse event occurred. Along with the increases in earthquake rate, the earthquake magnitudes also increased on average with more large earthquakes occurring in the latter stages of the swarms.

We examine the characteristics of the summit swarms to improve understanding of the failure processes involved in the summit collapse events. In particular, we focus on the inverse moment rate, which is a measure of seismic energy release over time. When all earthquakes are considered as part of the swarms, the character of the inverse moment rate of each swarm appears to change over the duration of the eruption, with major changes occurring concurrently with changes in the collapse event waveforms. This suggests that the failure processes may have evolved over time. We also consider sub-swarms of repeating earthquakes. Each family of repeating earthquakes can be assumed to come from one fault or area around the crater. Thus, the inverse moment rate of each family provides more detailed information about how the failure during each collapse event proceeded. Over the duration of the eruption, swarm families and the character of their inverse moment rates changed over time, providing more insight into the progression of the summit failure. We compare these results with other information about the collapse events to further understand the processes involved in the summit crater collapse.

Presenting Author: Gabrielle Tepp

Authors