Near-fault amplification and ground motion variability during the 2019 Ridgecrest, California sequence
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Abstract
We estimate ground-motion variability near the 2019 M 7.1 Ridgecrest earthquake sequence. Accurate seismic hazard estimation requires understanding ground-motion spatial correlations, yet many studies lack the dense station coverage needed to resolve small-scale variability. The 2019 M 7.1 Ridgecrest earthquake sequence presents a unique opportunity to examine ground motions and their spatial correlations at a range of interstation distances. The permanent seismic network was augmented with hundreds of temporary stations including several fault-crossing nodal arrays. We compute the event (δEi) and within-event (δWij) residuals from the observed peak ground velocity and peak ground acceleration data to isolate potential sources of ground-motion variability. We then compare δWij between station pairs that record an event to understand the semivariance of the ground motion versus interstation distance. By fitting an exponential model to the semivariances, we determine a correlation range of 25 km for the Ridgecrest region. Although the exponential model fits the broad-scale increase of semivariance with interstation distance, we also observe smaller-scale trends. We find that ground motions are less correlated for station pairs that are near or across faults that ruptured during the 2019 Ridgecrest sequence. We also find large, positive median δWij with relative values 2–3 times larger than nearby stations for individual stations’ near-fault traces. Near-fault amplification and greater ground-motion variability can delineate fault zones and may locally increase the seismic hazard.
Suggested Citation
Cochran, E.S., Parker, G.A., Minson, S.E., and Baltay, A.S., 2025, Near-fault amplification and ground motion variability during the 2019 Ridgecrest, California sequence: Bulletin of the Seismological Society of America, v. 116, no. 1, p. 467-481, https://doi.org/10.1785/0120250160.
ISSN: 1943-3573 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Near-fault amplification and ground motion variability during the 2019 Ridgecrest, California sequence |
| Series title | Bulletin of the Seismological Society of America |
| DOI | 10.1785/0120250160 |
| Volume | 116 |
| Issue | 1 |
| Publication Date | November 10, 2025 |
| Year Published | 2025 |
| Language | English |
| Publisher | Seismological Society of America |
| Contributing office(s) | Earthquake Science Center |
| Description | 15 p. |
| First page | 467 |
| Last page | 481 |
| Country | United States |
| State | California |
| City | Ridgecrest |