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Hydroacoustic, seismic, and bathymetric observations of the 2014 submarine eruption at Ahyi Seamount, Mariana Arc

July 2, 2019

Ahyi seamount, a shallow submarine volcano in the Northern Mariana Islands, began erupting on April 23, 2014. Hydroacoustic eruption signals were observed on the regional Mariana seismic network and on distant hydrophones, and NOAA scuba divers working in the area soon after the eruption began heard and felt underwater explosion sounds. The NOAA crew observed yellow orange bubble mats along the shore of neighboring Farallon de Pájaros island, but no other surface manifestations of the eruption were reported by the crew or observed in satellite data. Here, we detail the eruption chronology and its morphologic impacts through analysis of seismic and hydroacoustic recordings and repeat bathymetric mapping. Throughout the 2-week-long eruption, Ahyi produced several thousand short, impulsive hydroacoustic signals that we interpret as underwater explosions as well as tremor near the beginning and end of the sequence. The initial tremor, which occurred for 2 hours, is interpreted as small phreatomagmatic explosions. This tremor was followed by a 90 min pause before the characteristic impulsive signals began. Occasional tremor (lasting up to a few minutes) during the last 1.5 days of the eruption is interpreted as more sustained eruptive activity. Bathymetric changes show that a new crater, about 150 m deep, formed near the former summit and a large landslide chute formed on the southeastern flank. Comparing to other geophysically-detected submarine eruptions, we find that the signals from the 2014 Ahyi eruption were more similar to those from other shallow or at surface submarine eruptions than those at deep (>500 m) eruptions.

Publication Year 2019
Title Hydroacoustic, seismic, and bathymetric observations of the 2014 submarine eruption at Ahyi Seamount, Mariana Arc
DOI 10.1029/2019GC008311
Authors Gabrielle Tepp, William W. Chadwick, Matthew M. Haney, John J. Lyons, Robert Dziak, Susan Merle, Dave Butterfield, Charles W. Young
Publication Type Article
Publication Subtype Journal Article
Series Title Geochemistry, Geophysics, Geosystems
Index ID 70204499
Record Source USGS Publications Warehouse
USGS Organization Volcano Science Center