How Did the 2016 Mw 7.8 Kaikōura Earthquake Affect the Megathrust Earthquake Potential in the Hikurangi Subduction Zone?
Description:
The 2016 Mw 7.8 Kaikōura Earthquake occurred near the Hikurangi subduction zone (HSZ) and triggered slow slip events (SSEs), but not a megathrust earthquake. Considering the widespread SSEs along the HSZ, it is of interest to understand whether background and triggered aseismic processes may affect the megathrust earthquake potential. In this study, we use numerical simulations to investigate how the Kaikōura earthquake affected ongoing sequences of seismic and aseismic slip events in the HSZ. We use the open-source software Tandem to model quasi-dynamic seismic cycles with realistic slab geometry, convergence rate, and velocity structure along several representative profiles across the HSZ with varying degrees of interseismic locking, paleoseismicity, and spatiotemporal distribution of ongoing SSEs. For example, shallow and frequent East Coast SSEs and deep and less frequent Kaimanawa SSEs in northern HSZ are reproduced using depth-dependent normal stress with small asperities of increased pore fluid pressure embedded in a predominantly creeping fault. These seismic cycle models also produce occasional megathrust earthquakes that rupture areas of preceding SSEs. We validate the cycle models by comparing modeled surface displacements with GNSS data and comparing synthetic and data-driven locking models. These data-guided cycle models match the observed characteristics of the SSEs in different margins of HSZ, allowing the exploration of realistic triggering scenarios. We perturb the seismic cycle models using dynamic and static stress changes on the HSZ due to the Kaikōura earthquake calculated from existing dynamic (Ulrich et al., 2019) and kinematic (Inchin et al., 2021) models. The stress perturbation is applied at different stages in the megathrust earthquake cycle, with and without active SSEs. We examine the conditions in which megathrust earthquakes and SSEs are triggered in each profile. This study highlights the role of aseismic activities on the triggering potential of a megathrust earthquake as a response to a nearby crustal earthquake. Tandem Apps are accessible through QuakeWorx Science Gateway.
Session: Predictability of Seismic and Aseismic Slip: From Basic Science to Operational Forecasts [Poster]
Type: Poster
Date: 4/16/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Jeena
Student Presenter: Yes
Invited Presentation:
Poster Number: 49
Authors
Jeena Yun Presenting Author Corresponding Author j4yun@ucsd.edu University of California, San Diego |
Jeremy Wing Ching Wong wcwong@ucsd.edu University of California, San Diego |
Alice-Agnes Gabriel algabriel@ucsd.edu University of California, San Diego |
Yuri Fialko yfialko@ucsd.edu University of California, San Diego |
Laura Wallace lwallace@utexas.edu University of Texas at Austin |
Charles Williams C.Williams@gns.cri.nz GNS Science |
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How Did the 2016 Mw 7.8 Kaikōura Earthquake Affect the Megathrust Earthquake Potential in the Hikurangi Subduction Zone?
Session
Predictability of Seismic and Aseismic Slip: From Basic Science to Operational Forecasts