19-17. Distributed volcanism and distributed volcanic hazards in the U.S. Intermountain West

Although central volcanoes that erupt repeatedly, like shields and stratocones, tend to receive the most attention from volcanologists, most subaerial volcanoes are found in widely distributed volcanic fields made up of tens to hundreds of vents. These distributed fields occur in a variety of tectonic settings and present the full range of eruption styles and associated hazards. 

The United States Intermountain West hosts dozens of such distributed volcanic fields, and the USGS Volcano Science Center (VSC) is responsible for the monitoring and timely reporting of any potential hazards associated with resurgence of volcanic activity. Unfortunately, eruptive histories (time and style) are not well understood for the majority of U.S. distributed volcanic fields, and the fields are poorly monitored. Sparse geologic evidence suggests one eruption every 700 years in a typical volcanic field within the contiguous western U.S., meaning that it is more likely there will be an eruption from one of these fields during the next decades than an eruption from most Cascade volcanoes. The 1943 eruption of Paricutin, in Mexico, continued for 9 years; such an eruption today in the U.S. could directly impact nearby communities, air traffic, water reservoirs, transportation corridors, etc. Continued growth of cities, communities, and critical infrastructure near these sparsely monitored volcanic fields makes it increasingly important that we develop more robust hazards assessments. 

There are significant challenges in developing volcano hazards assessments and monitoring plans for these vast areas with poorly constrained eruption history. We do not know when or where the next eruption might occur, and we have very little data on which to base any estimates. For example, the Black Rock Desert Volcanic Field covers nearly 7,000km2 in central Utah and has been active for over six million years. This field has erupted cinder cones, shields, lava domes, maars, and a caldera, which collectively produce an array of volcanic hazards. The most recent eruption occurred only 720 years ago, and there will be eruptions in the field again; however, spatio-temporal and geochemical variations are not well known. Other fields, such as the San Francisco volcanic field, have some geochronologic data that suggest migration of activity over time. This has implications for the sites of potential future eruptions, but the trends are too poorly defined to be used with any reasonable degree of certainty. 

How can we successfully forecast future eruptions that might occur anywhere within these geographically large and tectonically complex regions? How do we improve our models of how such volcanic systems work, including the timescales of unrest and eruptive activity? And how do we prepare for rare but potentially widespread eruptive impacts? These questions point to several fundamental research challenges for distributed volcanic fields:  

• What are the recurrence rates, volumetric eruption rates, and distributions of eruption magnitudes within and between volcanic fields? 

• How can geophysical and geochemical investigations inform conceptual models of magma ascent and interaction with the crust, and how do we integrate those models into eruption forecasts? 

• How do we develop sufficient hazard assessments and eruption response plans for geographically large areas that span governmental jurisdictions? 

• How can we best monitor widespread, dispersed, rarely active volcanic systems? 

The VSC seeks a postdoctoral fellow who has expertise in geochemical, geophysical, and/or geological studies applied to melt generation, ascent, storage and/or eruption within distributed volcanic fields. The Fellow’s work will provide a better understanding of the location, timing and nature of eruptions in, and possibly between, volcanic fields. Research approaches could include geological investigations to establish a volcanological framework, geochronological studies aimed at understanding the timing of eruptive activity, geophysical measurements that target the structure and volume of magmatic systems, petrologic analyses to better understand the timescales and conditions of magma storage, ascent, and eruption, and other relevant approaches. 

Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas. 

Proposed Duty Station: Vancouver, WA 

Areas of PhD: Geophysics, petrology, volcanology, or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered). 

Qualifications: Applicants must meet one of the following qualifications: Research Geologist, Research Geodesist, Research Geophysicist 

(This type of research is performed by those who have backgrounds for the occupations stated above.  However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.) 

Human Resources Office Contact: Beverly Ledbetter, 916-278-9396, bledbetter@usgs.gov

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