EAR-PF: The role of temperature of the crust and lithosphere in the magnitude and style of far-field deformation: EarthScope Transportable Array in Interior Alaska

Nakai Jenny, Boulder CO

Investigators

Abstract

Dr. Jenny Nakai has been granted an NSF EAR Postdoctoral fellowship to carry out research and education activities at the University of New Mexico. Seismic data from the NSF-funded Transportable Array in Alaska and northwestern Canada are being utilized to investigate how deformation of a continent far from a plate boundary is controlled by the material properties of the Earth's crust and upper mantle. The influence of temperature, and therefore the strength, of the crust and upper mantle on topography of Interior Alaska north of the Alaska Range and a large (2000 km long), potentially weak continental fault are being explored. Analyzing the temperature of the crust and upper mantle will lead to improved understanding of why strike-slip faults form inland of major continental boundaries. Undergraduate students from underrepresented minorities in earth science are participating in the research. The PI is engaging in outreach to the Alaska Native Science and Engineering Program and Albuquerque Native American community college and undergraduate students in order to disseminate results and expose students to active Geophysics and Seismology research. Temperature of the lithosphere is known to influence the style of deformation inland of a major plate boundary (for example, in Tibet), but data sets on a continental scale in these environments are rare. The advent of the Transportable Array in Alaska and northwestern Canada provides the opportunity to investigate the strength profile of the crust and lithosphere. Key methodologies will include using Pn seismic velocities to constrain upper mantle lithologies and extrapolate upper mantle heat flow and investigating seismic energy attenuation using local earthquakes to infer temperature of the crust and upper mantle. The resulting lithologic and temperature constraints will be combined with local geologic information to recover strength profiles of the crust and lithosphere. The profiles will be interpolated to produce a 3D map of crustal and upper mantle strength throughout Interior Alaska, a region which the seismological community knows little about due to its inaccessibility. Results will be jointly interpreted with existing geophysical data to determine the role of rheology and temperature in the far-field deformation of the continent, and as a consequence, earthquake hazard in Interior Alaska. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.