Geophysics and Tectonics Seminar spring-2024

Human activity and climate change are rapidly transforming Earth's hydrological and glaciological systems, posing critical challenges for global water security, coastal communities, and ecosystem resilience. In recent years, geophysics has become pivotal in both tracking hydro-cryospheric changes and unveiling the physics behind them. In this talk, I will discuss insight gained from applying a comprehensive geophysical approach to two critical and rapidly evolving systems: The Sacramento Valley aquifer system in California and supraglacial lakes on the Greenland Ice Sheet. Combining GNSS, InSAR, and GRACE/-FO satellite observations with in situ groundwater level measurements and lithologic logs in the Sacramento Valley reveals that the aquifer system has transitioned from a primarily reversible to irreversible deformation regime over the 2021-22 drought, indicating severe permanent compaction and loss of aquifer storage capacity that pose a serious threat to California’s water resources and infrastructure. In Greenland, we harness observations from on-ice GNSS stations, satellite imagery, ice-penetrating radar, seismometers, and water pressure instruments to decipher how meltwater lakes that form at the surface of the ice sheet interact through englacial stress to rapidly funnel surface meltwater to the ice-sheet bed and modulate ice basal sliding. Together, these case studies highlight the importance of multi-technique geophysical surveys in understanding the Earth’s changing hydro-cryosphere and enabling space-based monitoring at the global scale.