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Surface wave phase velocity tomography across Alaska


The tectonic processes that characterize Alaska and the surrounding region remain relatively unstudied. Large-scale features of interest (Figure 1) include the Queen Charlotte-Fairweather fault system (a source of powerful earthquakes), the Aleutian arc (a chain of volcanic islands along the North American-Pacific plate boundary), and the subducting Yakutat plate, but the complex interactions between these features and the tectonic plate motions that govern them stand to be modeled with greater precision. My project seeks to learn more about these processes and to determine more about the crustal and lithospheric mantle structure beneath this region. This research uses wavefront tracking to perform surface wave tomography, which generates images of seismic wave speed variations at different depths inside the Earth. I utilize data primarily from the EarthScope Transportable Array, a dense network of seismometers (Figure 2) that is currently deployed in Alaska. Using vertical-component data from distant earthquakes with depths < 50 km and Mw > 6 that occurred between January 2014 and June 2018, I measure the travel times and amplitudes of Rayleigh waves at long periods (25-200 seconds), which are sensitive to the entire mantle lithosphere and even the upper asthenosphere (up to ~300 km depths). I use these measurements to generate maps of 2D variations in wave speed. Lower velocities may indicate higher temperatures and perhaps the presence of partially molten rock, while higher velocities may indicate lower temperatures and the absence of partially molten rock. The ultimate goal is to use these results to elucidate how plate motions and other geophysical processes operating in the crust and mantle control the distribution of volcanism, seismicity, and surface deformation in Alaska.


Quintal, Dylan, "Surface wave phase velocity tomography across Alaska" (2018). Summer Research Symposium. Brown Digital Repository. Brown University Library.



  • Summer Research Symposium

    Each year, Brown University showcases the research of its undergraduates at the Summer Research Symposium. More than half of the student-researchers are UTRA recipients, while others receive funding from a variety of Brown-administered and national programs and fellowships and go …