Gaining new insights into the magmatic and tectonic processes at Kilauea Volcano from analysis of data recorded by the 2018 RAPID OBS array

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In 2018, Kilauea Volcano, Hawaii underwent a series of major events including more than a 500-meter collapse of the summit, lava eruptions, and a magnitude 6.9 earthquake and its numerous aftershocks. The consequences of these events were extensive damage to infrastructure and property. In early July 2018, a team funded by the NSF Grants for Rapid Response Research (RAPID) program deployed 12 ocean bottom seismometers (OBSs) offshore Kilauea. Eleven of the twelve OBSs were recovered in mid-September. All but one of the recovered OBSs had useful seismic and hydroacoustic data for the full recording period. During the two-month OBS recording periods, around 16,000 magnitude 1 and larger earthquakes were located by the U.S. Geological Survey (USGS) Hawaiian Volcano Observatory (HVO), many occurring offshore or near the coast. Because all HVO seismic stations are on land, many offshore earthquakes were likely missed or poorly located in the USGS HVO catalog. Preliminary data analysis shows that the OBS deployment successfully captured a significant portion of abundant aftershock activity and spanned the termination of active lava eruption. It was the first time that such events are observed by concurrent onshore-offshore seismic arrays and these events provided an extraordinary opportunity to observe the interplay between magmatic and tectonic processes in exceptionally rich detail and dimension. This project is to analyze the OBS data to obtain a better understanding of the plumbing system and faults at Kilauea Volcano. The analyses will be done in collaboration with scientists at the USGS Hawaii Volcano Observatory, Western Washington University, and Rice University. The project supports the training of one graduate and two undergraduate students.In this project, we will analyze the data collected by the offshore OBSs to gain new insights into the magmatic and tectonic processes at Kilauea Volcano, focusing on four main scientific questions: (1) What structures within Kilauea's south flank were activated during the 2018 events, and what deformation did they accommodate? (2) What are the physical properties of the main faults? (3) How does deep magma migrate in space and time? And (4) What are the stress states of the submarine south flank? These are long-standing questions about the magmatic and tectonic processes at Kilauea Volcano and oceanic shield volcanoes in general. The answers will provide constraints on flank deformation and deep magma migration and will have implications for seismic hazards, submarine landslides, and tsunami risks. The data analyses will include detecting and locating earthquakes and determining the physical properties of major faults and stress states of the Kilauea south flank. The expected results include a catalog of offshore earthquakes and refined offshore velocity models, which will enable the development, with support by the USGS, of new offshore seismicity monitoring capabilities with the potential to enhance societal preparedness and resilience against such impacts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.