Collaborative Research: CEDAR: Sky-High Seismology: Decoding Upper Atmospheric Transcripts of Seismic Ruptures

Earthquakes that generate tsunamis can pose significant hazards to coastal communities, including those along the U.S. East and West Coasts, Alaska, Hawaii, and U.S. territories. Timely tsunami warnings depend on rapidly and accurately characterizing earthquake sources. However, ground- and ocean-based monitoring instruments are sparsely distributed, limiting the assessment of complex earthquake dynamics. This project addresses these observational gaps by investigating the upper atmosphere as a complementary sensor for natural hazards. Surface motion generated by earthquakes launches low-frequency acoustic waves with periods ranging from seconds or minutes that disturb the ionosphere in ways that can be detected using satellite navigation signals, providing an additional source of information about earthquakes and associated tsunamis. The project will support workforce development, foster international collaborations, and produce open-access software and datasets. By bringing together Earth science and space physics, the research will advance the scientific foundation for future ionosphere-based hazard monitoring and early-warning capabilities. The resulting methods may also support the detection and characterization of other impulsive events, including bolides and explosions, through their atmospheric wave signatures. The primary goal of this project is to advance ionospheric seismology from qualitative observations to rigorous, quantitative diagnostics to resolve the non-uniqueness of earthquake source models. The research investigates vertical coupling and electrodynamic feedback processes within the ionosphere-thermosphere system driven by co-seismic infrasonic acoustic waves. These waves travel to altitudes of 100-300 km, creating disturbances routinely tracked globally in near-real-time using everyday Global Positioning System/Global Navigation Satellite Systems (GPS/GNSS). The team will integrate atmosphere-ionosphere coupled models with seismic wave propagation models and perform direct comparisons with the GPS data suite. Using this methodology, the team will conduct demonstrative case studies of earthquakes to assess the sensitivity of GPS/GNSS signals to rupture dynamics under varying thermospheric and ionospheric background states. The work also evaluates wave-driven ionospheric dynamo currents as a secondary diagnostic. Technical contributions include delivering a robust, scalable, end-to-end seismic-ionospheric modeling pipeline resolving nonlinear coupled processes from the ground to the exobase. 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.