TY - JOUR
T1 - Tracking seismic velocity perturbations at Ridgecrest using ballistic correlation functions
AU - Sheng, Yixiao
AU - Mordret, Aurélien
AU - Brenguier, Florent
AU - Tomasetto, Lisa
AU - Higueret, Quentin
AU - Aubert, Coralie
AU - Hollis, Dan
AU - Vernon, Frank
AU - Ben‐Zion, Yehuda
N1 - Publisher Copyright:
© Seismological Society of America.
PY - 2024/7
Y1 - 2024/7
N2 - We present results based on data of a dense nodal array composed of 147 stations, deployed in 2022 near the epicenter of the 2019 MW 7.1 Ridgecrest earthquake to investigate characteristics of the seismic wavefields. Through array analyses, we identified two primary components. First, we observed far‐field P waves dominating the 0.5–1.2 Hz frequency range, which are likely primarily generated by wind‐driven oceanic swell activity. Second, we detected near‐field body waves resulting from anthropogenic activities in the frequency range 2–8 Hz. We examined noise correlation functions derived from data of the dense deployment and regional stations to explore fault‐zone seismic velocity changes using ballistic arrivals, with a focus on velocity perturbation shortly before and after the Ridgecrest earthquake sequence. Our findings exhibit distinct behavior compared to results obtained through standard coda‐wave interferometry. Particularly, we observed a decrease in P‐wave travel time on certain station pairs prior to the 2019 earthquake sequence. Supported by detailed investigation of the local seismic wavefields, we interpret the decreasing P‐wave travel time as likely caused by a velocity increase away from the fault, possibly related to fluid migration. However, additional information is necessary to verify this hypothesis.
AB - We present results based on data of a dense nodal array composed of 147 stations, deployed in 2022 near the epicenter of the 2019 MW 7.1 Ridgecrest earthquake to investigate characteristics of the seismic wavefields. Through array analyses, we identified two primary components. First, we observed far‐field P waves dominating the 0.5–1.2 Hz frequency range, which are likely primarily generated by wind‐driven oceanic swell activity. Second, we detected near‐field body waves resulting from anthropogenic activities in the frequency range 2–8 Hz. We examined noise correlation functions derived from data of the dense deployment and regional stations to explore fault‐zone seismic velocity changes using ballistic arrivals, with a focus on velocity perturbation shortly before and after the Ridgecrest earthquake sequence. Our findings exhibit distinct behavior compared to results obtained through standard coda‐wave interferometry. Particularly, we observed a decrease in P‐wave travel time on certain station pairs prior to the 2019 earthquake sequence. Supported by detailed investigation of the local seismic wavefields, we interpret the decreasing P‐wave travel time as likely caused by a velocity increase away from the fault, possibly related to fluid migration. However, additional information is necessary to verify this hypothesis.
UR - http://www.scopus.com/inward/record.url?scp=85197423347&partnerID=8YFLogxK
U2 - 10.1785/0220230348
DO - 10.1785/0220230348
M3 - Article
SN - 0895-0695
VL - 95
SP - 2452
EP - 2463
JO - Seismological Research Letters
JF - Seismological Research Letters
IS - 4
ER -