Volcanology seminars

A currently quiescent stratovolcano, Mount Shasta, California, still poses a significant hazard to nearby communities thanks to impactful non-eruptive debris flows that can occur throughout the year. In this work, we have built a more complete record of debris flow occurrence using monitoring campaigns and research into historical newspaper records; analyze debris flow frequency and triggering in the context of regional weather and climate patterns; and forecast the future of debris flow hazards at Mount Shasta. This topic is timely because of its relevance to the ongoing efforts to create up-to-date, usable, and relevant hazards assessments at United States Volcanoes, as well as a need expressed by local land managers for debris flow data. Ultimately, this work will not only enhance our understanding of debris flow occurrence at Mount Shasta, but will also aid stakeholders in land planning, hazard mitigation, and preparedness.

Graham Ryan examines how the Soufrière Hills volcano has shaped Montserrat since the eruption began in 1995. Fatalities, displacement and economic damage were followed by continuing volcanic unrest, leaving uncertainty even after eruptive activity stopped. The same geology also offers potential resources. The lecture considers indigenous geothermal electricity that could supply the island and research with the Oxford Martin School into extracting critical metals from magma-derived fluids. It connects ongoing volcanic risk with opportunities for energy independence and a more sustainable economic base.

Volcanic edifice flank collapses are low-frequency, high-magnitude events that can rapidly mobilize tens of km3 of material and transport it large distances (>10 km) from the edifice. In ocean basins, these failures induce secondary hazards through the generation of tsunamis that can impact both neighboring and distal coastlines. These high-risk, far-reaching events have historically generated significant damage and loss of life, such as the 1792 collapse of the Mayuyama dome (Japan) that led to ~15,000 fatalities, and recently the 2018 collapse of Anak Krakatau (Indonesia) that resulted in ~440 deaths. Globally, there are 400–800 oceanic and coastal volcanic edifices with the potential for future collapses and associated tsunamis. Although previous studies have evaluated edifice collapse potential at both single volcanoes and over entire arcs, a global assessment of the edifices that are most capable of producing a tsunami-generating collapse is incomplete, in part because of remote locations and lack of detailed investigations. Building on previous studies, we develop a multi-component weighting procedure to rank the potential for edifice flank collapse and tsunami generation using three criteria: 1) edifice morphology; 2) satellite-derived estimations on the extent of hydrothermal alteration; and 3) 3D slope-stability analysis of potential collapses. We test this approach on oceanic and coastal volcanic edifices from the Marianas, Aleutians, Indonesia, and Philippines. After describing the results and relative ranking of edifices with the highest potential for collapse, we discuss implications for future tsunami hazard assessment.