Collaborative Research: Driving forces at the top of the world: Characterizing the kinematics and dynamics of the eastern Eurasian and western North American Arctic

Michigan State University, East Lansing MI

Investigators

Abstract

An array of forces act on the Earth's crust in the Arctic (on the margins of Russia, Alaska, and Canada), giving rise to this region's active faults and earthquakes. Some of these forces are from sideways pushing by tectonic plates and from drag by the Pacific Plate as it slides beneath the Alaska crust. Other forces result from gravity acting on the high mountains and from buoyancy as the crust slowly recovers its shape following the loss of heavy ice sheets that once weighed the region down. New data from high-precision GPS sensors and seismometers now suggest that flow of the Earth’s mantle causes drag along the base of the crust, and also contributes to faulting and earthquakes. Flesch, Elliott, and their students will analyze all available GPS data from the region to make a detailed map showing how points in the surface are moving right now. They will make computer models representing the Arctic region as blocks bounded by active faults, and use this with the GPS velocity map to estimate how fast these faults are slipping, which is important for understanding earthquake risk. After this, they will develop more sophisticated computer models to understand which forces are most important for causing observed surface movements and fault slip rates, and how big these forces are. This project will determine a synoptic regionally internally consistent multi-tectonic plate scale velocity field by incorporating both GPS and mid-oceanic ridge spreading rates in the Arctic that represent motions over hundreds of thousands of years. This work will incorporate the most recent seismic analysis providing constraints on the geometry and strength of the lithosphere, perform instantaneous and time dependent 3-D geodynamic simulations of Alaska and the Arctic. Observed surface motions will be compared to the predicted velocities from the geodynamic simulations at the volume surface to address the questions: (1) How does gravity acting on topography in the Arctic and opening at the Gakkel ridge contribution to force balance in Alaska? (2) How do southward directed mantle tractions beneath northern Alaska distribute in central and southern Alaska? Does the generated uplift in the McKenzie mountains provide a torque responsible for rotation of the Bering plate? (3) Is there an incipient subduction zone forming at continental margin north of 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.