The Clear Lake Volcanic Field (CLVF) in Northern California is a long lived (~2 Ma) and currently active volcanic system located within the San Andreas Transform at the northern edge of the San Francisco Bay Area. Past magmatic activity in the CLVF is characterized by voluminous intrusion and extrusion, including caldera-forming eruptions. Surface manifestations of current volcanic activity include hot springs, fumaroles, seismicity, and the world’s largest producing geothermal field, The Geysers. Because of its proximity to the densely-populated Bay Area, long-lived history of explosive eruption, decades of deep long-period seismic events, a central silicic dome, and abundant young volcanic features, the National Volcano Early Warning System (NVEWS) has categorized the CLVF as a potentially high-risk volcanic hazard.
The CLVF is situated in a unique tectonic setting, lying between parallel strands of the active San Andreas Fault system and along the track of the northward migrating Mendocino Triple Junction, the nexus of three tectonic plates marking the southernmost subducting edge of the Gorda Plate beneath North America. Though it has long been hypothesized that CLVF magmatism is related to slab window processes, there is a suggestion that the trailing edge of the subducting slab somehow controls location and type of volcanism. Details of the deep heat source beneath the CLVF are not well understood, nor is the tectonic relationship between the CLVF, the edge of the subducting Gorda Plate and related slab window, and the San Andreas Fault system.
Geophysical data characterizing the CLVF include gravity, magnetic, seismic, geochemical, gas, and electromagnetic datasets, and were largely collected in the 1970’s – 1990’s. Very few of these datasets have been updated as methods and technology have greatly improved. The unique tectonic position of the CLVF related to major faults and subducting plates, proximity to the densely-populated Bay Area, its importance as a geothermal energy producer, and its potential for continued and possibly hazardous volcanic activity make further study of the system imperative.
We seek a Mendenhall Fellow to better characterize the seismic and volcanic hazard associated with the Clear Lake Volcanic Field. The candidate should have a strong background in geophysics, or a related field (e.g. physics, geology, math, computer science), and will address primary CLVF research questions such as:
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What is the nature of the magmatic system?
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How is the slab window beneath CLVF related to the subducted Gorda Plate, and can CLVF be used as a general model for tectonic settings near the edge of subducting plates?
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How do the CLVF and San Andreas Fault system interact?
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How deep is the heat source beneath the CLVF and what is its geometry?
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Is magmatic storage and transport concentrated along pre-existing structural boundaries?
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Are there similarities between the CLVF and the geothermally and tectonically active Coso Volcanic Field in southeastern California?
Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.
Proposed Duty Station: Menlo Park, CA
Areas of PhD: Geology, seismology, geophysics, mathematics 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 the qualifications for: Research Geologist, Research Geophysicist, Research Mathematician.
(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: Audrey Tsujita, 916-278-9395, atsujita@usgs.gov
