Natural time analysis of quasi-periodic caldera collapse events during the 2018 Kīlauea volcano eruptive sequence

Rebecca A. Fildes, Donald L. Turcotte, & John B. Rundle

Submitted August 12, 2019, SCEC Contribution #9451, 2019 SCEC Annual Meeting Poster #038

The period of heightened volcanic and seismic activity occurring at Kīlauea volcano on the island of Hawai’i, USA from late spring through summer 2018 included a remarkable quasi-periodic sequence of caldera collapse events. From early-June to early-August, 47 collapse events, each releasing the energy equivalent of a Mw 5.3 ± 0.1 earthquake, occurred about every 1.30 days with over 300 M ≥ 2.5 earthquakes occurring between sequential collapses. Nowcasting is a type of statistical analysis that uses small magnitude events to estimate the occurrence of large magnitude events. This is done utilizing the concept of natural time in which time is counted by small magnitude event occurrences between large magnitude events, not in terms of clock time (days passed). This method can produce a “nowcasted” set of large earthquakes, for this study large collapse events, that are in good agreement with the actual catalogued number of events. This analysis is not a single fault-based model, but is based on regional seismicity in an area that can include many different faults and provides insight into the changing stress state and seismic hazard in that region. Therefore, the summit caldera region of Kīlauea, which underwent a large amount of deformation with relatively fast changes in fault structure during this period of heightened activity, is a good candidate to which to apply a regional seismic hazard analysis approach such as nowcasting. The subset of 47 collapse events used in this study displayed the strongest temporal periodicity and had an abundance of smaller seismicity occurring between them, making them the best candidates of the 62 total large collapse events which occurred during the 2018 Kīlauea sequence. Previously applied to tectonic earthquakes and induced seismicity over longer time frames, this is the first test of nowcasting large caldera collapse events in volcanic associated seismicity and on a relatively short time scale.

Citation
Fildes, R. A., Turcotte, D. L., & Rundle, J. B. (2019, 08). Natural time analysis of quasi-periodic caldera collapse events during the 2018 Kīlauea volcano eruptive sequence. Poster Presentation at 2019 SCEC Annual Meeting.


Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)