Larry G. Mastin, Ph.D.
I have spent much of my career working to understand, assess, and mitigate the hazards of volcanic ash.
To understand the nature of the hazard, I have studied tephra deposits in the field and designed experiments to generate volcanic ash in the laboratory. I also develop and use models that simulate the ascent of magma in conduits, rise of ash in volcanic plumes, and downwind movement of ash clouds. I have been involved in the development and application of several models that simulate these processes.
I have worked with emergency managers, Volcanic Ash Advisory Centers, and specialists from more than a dozen volcano observatories around the world to improve the accuracy of volcanic ash forecasts, both for aviation safety and for ground-based communities. From 2010-2020 I served as co-chair of the World Meteorological Organization’s Volcanic Ash Scientific Advisory Group, an expert panel dedicated to advising Volcanic Ash Advisory Centers on the science and practice of volcanic ash-cloud detection and forecasting.
My professional life began as a mud logger working on the North Slope of Alaska in 1980-81. While studying for my master’s degree at Stanford in 1982-84, I worked part time for the Tectonophysics branch of the USGS in Menlo Park, California, where I assisted with hydraulic fracturing stress measurements, and studied the growth of fractures and the development of breakouts, i.e. stress-induced zones of failure, around boreholes in sandstone.
My Ph.D. work at Stanford, from 1984-1988, under Professor David Pollard, involved field and laboratory study of the growth of surface faults above a shallow dike in Long Valley Caldera, California. A second half of this study focused on how the dike heated groundwater that erupted to produce several large explosion craters, the Inyo Craters, north of the town of Mammoth Lakes.
After completing my Ph.D., I worked from 1988-1990 as a post-doctoral researcher in the Geophysics Institute at the University of Karlsruhe, Germany. My tasks included compiling data for the European part of a World Stress Map project, and examining the state of stress at a deep drillhole site in northern Bavaria.
At the Cascades Volcano Observatory, from 1990 through the late 2000s, I concentrated on the role of water in the style and timing of eruptions. This work involved, for example, an examination of correlations between rainfall and gas explosions at Mount St. Helens; on the conditions that produced explosive phreatomagmatic eruptions at Kilauea, and effects of turbulent water-magma mixing on eruptive style.
Since the late 2000s, I have been involved primarily in volcanic ash hazards, as described above.
Education and Certifications
1988 Ph.D. Geomechanics, Stanford University
1984 M.S. Engineering Geology, Stanford University
1980 B.S. Geology, University of California, Davis (cum Laude)
Affiliations and Memberships*
Fellow, Geological Society of America
Member, American Geophysical Union
Member, International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI)
Member, American Meteorological Society
Member, American Association
Honors and Awards
2018: Fellow, Geological Society of America
Abstracts and Presentations
2021: “Comparing the hazards of wildfire smoke and volcanic ash in the Pacific Northwest”, invited talk in the Cascadia Wildfire and Urban Smoke seminar series, sponsored by Portland State University and the Cascadia Innovation Corridor Iniative (search for it on YouTube)
2020: “Protecting air travel from volcanic ash in the coming decade”, invited talk V08-15 at 2020 American Geophysical Union Fall Meeting.
2016: “Forecasting Ashfall Impacts from a Yellowstone Supereruption”, USGS Menlo Park Public Lecture, May 26, 2016, https://www.usgs.gov/media/videos/forecasting-ashfall-impacts-a-yellowstone-supereruption
Science and Products
Asteroid impacts - downwind and downstream effects
Near-real-time volcanic cloud monitoring: Insights into global explosive volcanic eruptive activity through analysis of Volcanic Ash Advisories
Turbulence, entrainment and low-order description of a transitional variable-density jet
A probabilistic assessment of tephra-fall hazards at Hanford, Washington, from a future eruption of Mount St. Helens
Comparing simulations of umbrella-cloud growth and ash transport with observations from Pinatubo, Kelud, and Calbuco volcanoes
Did ice-charging generate volcanic lightning during the 2016–2017 eruption of Bogoslof volcano, Alaska?
Investigating the accuracy of one‐dimensional volcanic plume models using laboratory experiments and field data
Laboratory experiments of volcanic ash resuspension by wind
Modeling ash dispersal from future eruptions of Taupo supervolcano
Globally detected volcanic lightning and umbrella dynamics during the 2014 eruption of Kelud, Indonesia
New Zealand supereruption provides time marker for the Last Glacial Maximum in Antarctica
Ongoing efforts to make ash-cloud model forecasts more accurate
Science and Products
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Filter Total Items: 53
Asteroid impacts - downwind and downstream effects
For this abstract, we have selected an impact location, consistent with the PDC2021 initial scenario [1], in the San Juan Mountains, in southwestern Colorado. This is a low-density population area but is part of the watershed system within the Colorado River basin, a major source for water and power for the southwestern United States. Several large cities and major airports are potentially downwinAuthorsTimothy N. Titus, D. G. Robertson, Joel B. Sankey, Larry G. MastinNear-real-time volcanic cloud monitoring: Insights into global explosive volcanic eruptive activity through analysis of Volcanic Ash Advisories
Understanding the location, intensity, and likely duration of volcanic hazards is key to reducing risk from volcanic eruptions. Here, we use a novel near-real-time dataset comprising Volcanic Ash Advisories (VAAs) issued over 10 years to investigate global rates and durations of explosive volcanic activity. The VAAs were collected from the nine Volcanic Ash Advisory Centres (VAACs) worldwide. InfoAuthorsSamantha Engwell, Larry G. Mastin, Andrew C. Tupper, Jamie Kibler, Paula Acethorpe, G. Lord, R. FilgueiraTurbulence, entrainment and low-order description of a transitional variable-density jet
Geophysical flows occur over a large range of scales, with Reynolds numbers and Richardson numbers varying over several orders of magnitude. For this study, jets of different densities were ejected vertically into a large ambient region, considering conditions relevant to some geophysical phenomena. Using particle image velocimetry, the velocity fields were measured for three different gases exhauAuthorsBianca Viggiano, Tamara Dib, Nasim Ali, Larry G. Mastin, Raul Bayoan Cal, Stephen A. SolovitzA probabilistic assessment of tephra-fall hazards at Hanford, Washington, from a future eruption of Mount St. Helens
Hanford, Washington (USA) is the construction site of a multi-billion-dollar high-level nuclear waste treatment facility. This site lies 200 kilometers (km) east of Mount St. Helens (MSH), the most active volcano in the contiguous United States. Tephra from a future MSH eruption could pose a hazard to the air intake and filtration systems at this plant. In this report, we present a probabilistic eAuthorsLarry G. Mastin, Alexa R. Van Eaton, Hans F. SchwaigerComparing simulations of umbrella-cloud growth and ash transport with observations from Pinatubo, Kelud, and Calbuco volcanoes
The largest explosive volcanic eruptions produce umbrella clouds that drive ash radially outward, enlarging the area that impacts aviation and ground-based communities. Models must consider the effects of umbrella spreading when forecasting hazards from these eruptions. In this paper we test a version of the advection–dispersion model Ash3d that considers umbrella spreading by comparing its simulaAuthorsLarry G. Mastin, Alexa R. Van EatonDid ice-charging generate volcanic lightning during the 2016–2017 eruption of Bogoslof volcano, Alaska?
The 2016–2017 shallow submarine eruption of Bogoslof volcano in Alaska injected plumes of ash and seawater to maximum heights of ~ 12 km. More than 4550 volcanic lightning strokes were detected by the World Wide Lightning Location Network (WWLLN) and Vaisala’s Global Lightning Dataset (GLD360) over 9 months. Lightning assisted monitoring efforts by confirming ash-producing explosions in near-realAuthorsAlexa R. Van Eaton, David J. Schneider, Cassandra Marie Smith, Matthew M. Haney, John J. Lyons, Ryan Said, David Fee, Robert H. Holzworth, Larry G. MastinInvestigating the accuracy of one‐dimensional volcanic plume models using laboratory experiments and field data
During volcanic eruptions, model predictions of plume height are limited by the accuracy of entrainment coefficients used in many plume models. Typically, two parameters are used, α and β, which relate the entrained air speed to the jet speed in the axial and cross‐flow directions, respectively. To improve estimates of these parameters, wind tunnel experiments have been conducted for a range of crAuthorsJames S. McNeal, Larry G. Mastin, Raul B. Cal, Stephen A. SolovitzLaboratory experiments of volcanic ash resuspension by wind
Fresh volcanic eruption deposits tend to be loose, bare, and readily resuspended by wind. Major resuspension events in Patagonia, Iceland, and Alaska have lofted ash clouds with potential to impact aircraft, infrastructure, and downwind communities. However, poor constraints on this resuspension process limit our ability to model this phenomenon. Here, we present laboratory experiments measuring tAuthorsVicken Etyemezian, Jack Gillies, Larry G. Mastin, Alice Crawford, Robert Hasson, Alexa R. Van Eaton, G. NikolichModeling ash dispersal from future eruptions of Taupo supervolcano
Hazard analysis at caldera volcanoes is challenging due to the wide range of eruptive and environmental conditions that can plausibly occur during renewed activity. Taupo volcano, New Zealand, is a frequently active and productive rhyolitic caldera volcano that has hosted the world's youngest known supereruption and numerous smaller explosive events. To assess ashfall hazard from future eruptions,AuthorsSimon J Barker, Alexa R. Van Eaton, Larry G. Mastin, Colin JN Wilson, Mary Anne Thompson, Tom M Wilson, Cory Davis, James A RenwickGlobally detected volcanic lightning and umbrella dynamics during the 2014 eruption of Kelud, Indonesia
Volcanic lightning shows considerable promise as a monitoring and research tool to characterize explosive eruptions. Its key strengths are rapid and remote detection, because the radio signals produced by lightning can propagate thousands of km at the speed of light. Despite these tantalizing properties, the scientific work on volcanic lightning has only recently started gaining momentum. Much morAuthorsKirstin A Hargie, Alexa R. Van Eaton, Larry G. Mastin, Robert H. Holzworth, John W. Ewert, Michael J. PavolonisNew Zealand supereruption provides time marker for the Last Glacial Maximum in Antarctica
Multiple, independent time markers are essential to correlate sediment and ice cores from the terrestrial, marine and glacial realms. These records constrain global paleoclimate reconstructions and inform future climate change scenarios. In the Northern Hemisphere, sub-visible layers of volcanic ash (cryptotephra) are valuable time markers due to their widespread dispersal and unique geochemical fAuthorsNelia W. Dunbar, Nels A. Iverson, Alexa R. Van Eaton, Michael Sigl, Brent V. Alloway, Andrei V. Kurbatov, Larry G. Mastin, Joseph R. McConnell, Colin J. N. WilsonOngoing efforts to make ash-cloud model forecasts more accurate
The 2010 eruption of Eyjafjallajökull volcano in Iceland changed the rules for air travel in Europe and introduced the use of restricted fly zones based on ash-cloud concentrations calculated by dispersion models. This change prompted a sustained effort to improve the accuracy of ash-cloud model forecasts. In this paper we describe how this goal is being advanced on three fronts: (1) assessing curAuthorsLarry G. Mastin, Alexa R. Van Eaton, David J. Schneider, Roger P. Denlinger - Software
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*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government