V002-0001
An improved earthquake catalog during the 2018 Kīlauea Volcano eruption from combined onshore and offshore seismic arrays

Monday, 7 December 2020
Poster
Xiaozhuo Wei, University of Rhode Island, Narragansett, RI, United States, Yang Shen, University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, United States, Jacqueline Caplan-Auerbach, Western Washington University, Bellingham, WA, United States and Julia Morgan, Rice University, Earth and Planetary Sciences, Houston, TX, United States
Abstract:
The 2018 eruption was the most intense eruption of Kilauea Volcano in the last 200 years. The eruption was monitored by a comprehensive network of geophysical and geochemical sensors spread across the volcano. In addition to the permanent seismic networks, a rapid-response nodal array, an ocean-bottom-seismometer (OBS) array and a temporary broadband array were deployed in response to the unfolding events. It was the first time that such an eruption was observed by concurrent onshore-offshore seismic arrays and an accurate earthquake catalog could help to better understand the eruption process. In this presentation, we report earthquake activities during the eruption determined from the onshore-offshore seismic data.

All the seismic data from March 1st, 2018 to September 16th, 2018 were collected to perform earthquake detection. Recursive STA/LTA triggers were used to detect earthquakes from continuous data streams. Detections were associated with different events based on the moving window of 6 km/s and 3 km/s, before located individually. The P and S arrivals were picked using a kurtosis-rate-based picker. The arrival time picking was performed on traces after polarization decomposition, when three component data were available. Some of the nodal network stations were not used due to large traffic-induced noise, as many of their sites were along the local roads.

The resulting preliminary catalog contains more than three times the number of earthquakes in the Hawaiian Volcano Observatory (HVO) catalog. The addition of the OBS array resulted in over a thousand unique earthquakes under the submarine south flank that are not in the HVO catalog. Furthermore, the number of earthquakes detected in the caldera region also increased, due to the inclusion of the rapid-response nodal array. A sharp drop in the daily number of earthquakes in the caldera region, which marked the end of caldera collapses, was followed by a rapid rise and then oscillating and gradual decrease in earthquake activities in both the East Rift Zone and the submarine south flank, indicating a complex interplay among the tectonic-volcanic units of Kilauea Volcano.

Previous Abstract | Next Abstract >>