RAPID: The East Anatolian fault earthquake sequence of 6 February 2023: epicentral afterslip and anticipated future rupture propagation

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

The PI proposes to build four "extensometers", which are devices that precisely measure offsets across faults exposed at the Earth's surface, and install them along the East Anatolian Fault Zone (EAFZ) in Turkey. The EAFZ is responsible for the M 7.8 and M 7.5 6 February 2023 earthquakes that recently devastated much of southeastern Turkey. These instruments will measure in detail how slow-motion offset along the fault is continuing, weeks to months after the earthquakes - and in the event of future earthquakes, they will measure sudden or gradual offsets across the fault. This information helps seismologists understand how earthquakes occur, estimate the probability of future large earthquakes in the region, and identify parts of the EAFZ that tend to move gradually instead of generating large earthquakes. The PI will be doing this work with Turkish scientists he knows well and has worked with in the past. He and his collaborators will also make needed repairs to extensometers monitoring other dangerous faults in Turkey, so they can send out their data in real time via 5G cellular service. The PI proposes to install four extensometers along segments of the East Anatolian Fault that were loaded by the 6 February 2023 M 7.8 and M 7.5 earthquakes. The extensometer data, together with seismic and geodetic observations, will provide information about ongoing postseismic creep and stress transfer, which feeds into probabilistic estimates of seismic hazard. These data will also constrain frictional properties of the EAFZ seismogenic zone and provide coseismic and postseismic slip constraints for potential, future EAFZ earthquakes. In addition to installing and telemetering new extensometers, the PI will work with Turkish colleagues to upgrade the telemetry on existing GAGE extensometers along the North Anatolian Fault Zone (NAFZ) to 5G. Bilham will work closely with Turkish scientists from Istanbul Technical University and Kandilli Observatory, strengthening an existing collaboration and sharing creepmeter design, installation, and interpretation knowledge with students. The new creep data will be freely and publicly shared via the UNAVCO/GAGE data archive. 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.