Investigating rupture characteristics of global large earthquakes with advanced seismic array back-projection

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Large earthquakes can cause devastating ground shaking and tsunamis, but understanding their rupture behavior in real time remains a major scientific challenge. This project aims to improve imaging and interpretation of the rupture processes of large earthquakes around the world. By improving an analysis method that uses waves recorded by seismic array called "back-projection," it is possible to visualize an earthquake rupture in time and space. The outcome of this research will produce more accurate measurements of how fast and how far earthquake ruptures travel. The results will help scientists identify unusual behaviors of large earthquakes like so called ‘super-shear ruptures’, which radiate unusually intense shaking. The findings of this study may lead to better earthquake early warning and hazard mitigation strategies. This research also provides valuable training to graduate students and includes science outreach efforts to engage K–12 students and the broader public through hands-on activities and educational field trips. The outcomes will support public safety by advancing our fundamental knowledge of how earthquakes happen. This project aims to systematically investigate the rupture characteristics of global large earthquakes (M ≥ 7.0) from 2000 to 2022 using advanced seismic back-projection (BP) techniques. Applying the Slowness-Enhanced Back-Projection method to correct spatial errors caused by 3D Earth structures will allow more accurate estimates of rupture speed, extent, and segmentation. This work will expand the geographical reach of BP by incorporating core-phase BP techniques that utilize PKIKP and PKP phases to image events from near-antipodal distances. A key goal is to build a comprehensive global database of rupture histories, which will be made publicly available. The investigators will perform synthetic tests using Incoherent Green’s Functions to quantify uncertainties and identify artifacts such as shadowing and tailing effects in BP imaging. The database will serve as a foundation for analyzing complex rupture behaviors, including the prevalence and dynamics of super-shear ruptures and the potential for ruptures to extend beyond the down-dip limit of the seismogenic zone. We will test hypotheses related to dynamic weakening mechanisms through earthquake cycle simulations using 2.5-dimensional spectral element modeling. These observations and models will be compared to determine the physical conditions that promote super-shear rupture and rupture depth extension. Ultimately, this research will improve the fidelity of rupture imaging, provide benchmark datasets for theoretical modeling, and enhance the ability to interpret the physics governing earthquake rupture processes. 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.