The Interactions of Glacial Isostatic Adjustment and Plate Tectonic Processes

The weight of thick ice sheets from the last ice age depressed the land surface and pushed the underlying mantle away. Since the melting of these ice sheets, the land has been rebounding upwards as the underlying mantle returns. This process affects plate motions and seafloor spreading rates. This project will determine how glacial forcing affects the San Andreas fault and earthquake hazards. The project will also assess how ongoing rapid deglaciation in Greenland affects volcanic eruptions in Iceland. Project results will determine how glacial uplift and mantle convection processes interact with each other. This project will promote society's understanding of Earth hazards and computing for geoscience research. It will also build the STEM workforce of the future. Dynamic processes determine Earth’s long-term thermal history and large-scale plate tectonics on timescales of many millions of years, while glaciation cycles operate on timescales of 40,000 to 100,000 years. These competing processes represent significant mass movement on Earth’s surface in the past few million years. Glacial isostatic adjustment (GIA) due to glacial cycles affects global sea-level change, erosional and depositional processes, tectonics, and Earth’s rotation. Recent research established an interplay between tectonic processes and GIA, as regulated by mantle viscosity. This project will develop a mantle viscosity model that is consistent with the observations of sea level, GIA-induced crustal motion and gravity change, structures of subducted slabs, and geoid anomalies above subduction zones. Mantle convection and GIA models will be computed to predict the present-day geoid, convective slab structures, relative sea level, and crustal motions. This will lead to a unified mantle viscosity structure to examine the effects of GIA on plate motions at mid-ocean ridges and across the San Andreas fault system. This project will further develop the open-source software packages for modeling mantle convection, viscoelastic deformation, and tidal deformation on global and regional scales. 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. NSF Award ID: 2544796 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Shijie Zhong | Institution: University of Colorado at Boulder, Boulder, CO | Award Amount: $414,127 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2544796 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2544796.html