Revised kinematic slip model of the 2019 Ridgecrest (California) earthquakes

The published slip model of Jin and Fialko (2020) features a complex rupture geometry in the shallow crust, including a “flower structure” formed by intersecting splay faults. Slip inversions were performed using the first-order Tikhonov regularization to moderate extreme variation in slip between the adjacent slip patches, including between slip patches that belonged to different sub-faults. This resulted in a highly peaked along-strike averaged normalized coseismic slip at the bottom of the inferred flower structure (3-4 km, Figure 15a in Jin and Fialko, 2020). However, in case of bifurcating faults, or “Y-shaped” fault intersections, a more appropriate regularization would be to preserve the slip budget between the bifurcated fault strands and a “parent” fault segment such that \(U_s^1 + U_s^2 = U_p\), where \(U_s^1, U_s^2\) are slip components that belong to two (or more) splay faults, and \(U_p \) is the respective slip component on the parent fault (Jin and Fialko, 2021). We re-run inversions of space geodetic data for the Ridgecrest earthquakes, as described in Jin and Fialko (2020), but with the imposed “slip budget” constraint for the intersecting faults. 

References:

Jin, Z., & Fialko, Y. (2020). Finite slip models of the 2019 Ridgecrest earthquake sequence constrained by space geodetic data and aftershock locations. Bull. Seism. Soc. Am., 110, 1660–1679.

Jin, Z., & Fialko, Y. (2021). Coseismic and early postseismic deformation due to the 2021 M7.4 Maduo (China) earthquake. Geophys. Res. Lett., 48, e2021GL095213.