Structure, Stress, Earthquake Sources, and Dynamic Triggering in Katmai, Alaska

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The investigators will study earthquakes, crustal structure, and stress in the Katmai area of Alaska, taking advantage of data collected by a dense, temporary seismic array. The seismic array was deployed in 2008, centered on Trident volcano, and will be operated through mid-2010. Katmai was the locus of the largest volcanic eruption in the 20th century and is one of the most seismically active volcanic regions in the United States. Based on previous research, it is likely that a magma reservoir resides under the Katmai Pass area. The research focus will be on the subsurface structure beneath this area, the types of earthquakes that are occurring and their possible implications for storage and movement of magma, and the forces that are driving the seismic and volcanic activity. This project is important for understanding the volcanic hazard posed by Katmai. This project involves the analysis of data from a temporary array of 11 three-component, broadband seismic instruments deployed in July 2008 in a 15 km diameter area centered on Katmai Pass, Alaska, supplemented by data from the surrounding Alaska Volcano Observatory (AVO) network stations. The temporary array will operate until late spring or early summer 2010. Katmai was the locus of the largest volcanic eruption in the 20th century and is one of the most seismically active volcanic regions in the United States. The main goals of the study are to explore the subsurface structure, seismicity, source mechanisms, state of stress, and earthquake triggering in the Katmai area. The research will focus on velocity and attenuation tomography, seismicity, source mechanisms, and shear wave splitting studies. The tomography work, including both P and S models for velocity and attenuation, will be aimed at determining if a magma body is present beneath the Katmai Pass area. The velocity model will be used to obtain accurate earthquake locations and fault plane solutions. The relocated seismicity and source mechanisms will be used to examine the character of the seismogenic structures beneath the area, and the source mechanisms and shear wave splitting will yield insight into the state of stress. They will also explore the process of dynamic triggering of earthquakes using data from their array.