Hydroacoustic Recordings of Lava-Water Interactions During the 2018 Eruption of Kilauea Volcano

Session: Ocean Bottom Seismology – New Data, New Sensors, New Methods [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

The majority of lava erupted during the 2018 Lower East Rift Zone eruption on Kilauea Volcano was emplaced offshore. This resulted in the formation of nearly 900 acres of new land and offshore deposits exceeding 200 meters in thickness. Emplacement of this material was often a passive process, with lava flows observed flowing into the sea. At other times, however, violent littoral explosions were observed, some of which posed significant a threat to tour boats in the area.

Signals from these and other eruptive processes were recorded by a network of ocean-bottom seismometers deployed on Kilauea’s submarine south flank. Hydrophones included in the instrument package recorded sounds that reflect different mechanisms of lava-water interaction. These signals include high frequency (10-100 Hz) bursts, continuous low-frequency (< 10 Hz) tremor and broadband signals lasting 10s of seconds. These signals are interpreted as lava-water explosions, tremor caused by flowing lava and submarine mass wasting events, respectively. The intensity of hydroacoustic activity near the ocean entry varied over the course of hours. We propose that increases in lava flux, observed in association with summit collapse events (Patrick et al., 2019) result in increased explosive activity at the ocean entry that manifests as increased acoustic signal strength. We use ray tracing, along with variations in signal amplitude and reflected phases, to distinguish events from different ocean entries or source depths. The hydroacoustic data reveal that most activity at the Kilauea ocean entry was constructive rather than destructive: the number of landslide events is significantly lower than observed ocean entries active during the Pu`u O`o eruption despite steeper slopes. This may be due to differences in the material properties of the growing deltas that, for the 2018 eruptions, are coarser grained and include intact lava flows that traverse the delta from the shoreline to the toe.

Presenting Author: Jacqueline Caplan-Auerbach

Authors