The break of earthquake asperities imaged by distributed acoustic sensing

Jiaxuan Li, Taeho Kim, Nadia Lapusta, Ettore Biondi, & Zhongwen Zhan

Published August 2, 2023, SCEC Contribution #12737

Rupture imaging of megathrust earthquakes with global seismic arrays revealed frequency-dependent rupture signatures, but the role of high-frequency radiators remains unclear. Similar observations of the more abundant crustal earthquakes could provide critical constraints but are rare without ultra-dense local arrays. Here, for the first time, we use the distributed acoustic sensing technology to image the high-frequency earthquake rupture radiators. By converting a 100-kilometer dark-fiber cable into a 10,000-channel seismic array, we image four high-frequency subevents for the 2021 Antelope Valley, California, Mw 6.0 earthquake. After comparing our results with long-period moment release and dynamic rupture simulations, we suggest that the imaged subevents are due to the breaking of fault asperities – stronger spots or pins on the fault - that modulate substantially the overall rupture behavior. An otherwise fading rupture propagation could be promoted by the breaking of fault asperities in a cascading sequence. This study highlights how we can use the extensive pre-existing fiber networks as high-frequency seismic antennas to systematically investigate the rupture process of regional moderate-sized earthquakes. Coupled with dynamic rupture modeling, it could improve our understanding of earthquake rupture dynamics.

Li, J., Kim, T., Lapusta, N., Biondi, E., & Zhan, Z. (2023). The break of earthquake asperities imaged by distributed acoustic sensing. Nature, 620(7975), 800-806. doi: 10.1038/s41586-023-06227-w.