Long‐Range Multi‐Year Infrasonic Detection of Eruptive Activity at Mount Michael Volcano, South Sandwich Islands

• Published in: Geophysical research letters Vol. 49; no. 7
• Main Authors: De Negri, R. S., Rose, K. M., Matoza, R. S., Hupe, P., Ceranna, L.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.04.2022
• Subjects: Acoustic waves; acoustics; Annual variations; Atmospheric models; Atmospheric structure; Empirical analysis; Eruptions; Infrasound; Islands; long‐range; Methods; Monitoring; Monitoring systems; Mount Michael; Propagation; Ray tracing; Remote observing; remote volcano; Satellite observation; Satellites; Spacecraft recovery; Stratospheric winds; Transmission loss; Volcanic activity; volcanic eruption; Volcanism; Volcanoes; Waveguides; South Sandwich Islands; Antarctica
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL096061

Mount Michael stratovolcano, South Sandwich Islands is extremely remote and challenging to observe, but eruptive activity has been sporadically observed since 1820 and captured by satellite methods since 1989. We identify long‐range infrasound signals recorded by the International Monitoring System attributable to episodes of persistent eruptive activity at Mount Michael. Analysis of multi‐year (2004–2020) infrasound array data at station IS27, Antarctica (range 1,672 km) reveals candidate signals especially from May 2005 to January 2008 and from May 2016 to April 2018. By combining ray‐tracing with empirical climatologies and atmospheric specifications, we show that systematic variations in the observed backazimuth of the signals (at IS27) are broadly consistent with annual variability in stratospheric propagation conditions for a source at Mount Michael. Observed signal amplitudes combined with transmission loss estimates are consistent with moderate explosive eruption. We highlight a selection of infrasound signals that correspond to satellite observation of eruptions. Plain Language Summary Atmospheric infrasound is an acoustic wave with frequencies in the range ∼0.01–20 Hz, less than the human hearing threshold. Infrasound from explosive volcanism can propagate hundreds to thousands of kilometers in atmospheric waveguides under favorable stratospheric wind conditions. The utility and limitations of infrasound for detecting and cataloging Earth's volcanism is presently under investigation. Mount Michael stratovolcano, South Sandwich Islands is extremely remote and challenging to observe, but eruptions there have been captured by satellite methods since 1989. Using data from the International Monitoring System infrasound network, we identify long‐range infrasound signals recorded at a distance of 1,672 km from Mount Michael at an infrasound station IS27 in Antarctica. The signals recorded in Antarctica can be plausibly attributed to eruptive activity at Mount Michael based on modeling the infrasound propagation in the atmosphere using ray‐tracing and empirical knowledge of time‐varying atmospheric structure. We also highlight a selection of the infrasound signals that correspond to satellite observation of eruptions. Key Points Long‐range (1,672 km) infrasonic detections attributed to eruptions at Mount Michael, Saunders Island Mount Michael is a remote volcano with no local ground‐based geophysical observations, but Saunders Island a significant penguin habitat Remote infrasound supports prior satellite‐based detections of eruptions and provides complementary time‐series of possible eruption events