Modeling the Proposed Deep Slab-Deformation Processes Behind Potential Precursory Signals Preceding Large Subduction Zone Earthquakes
Description:
Recent studies suggest that large-scale, transient signals in GNSS velocities, satellite gravity measurements, and intermediate-depth foreshock occurrences may precede large earthquakes in subduction zones. Specifically, investigations focused on the 2011 Mw 9.0 Tohoku-Oki and the 2010 Mw 8.8 Maule earthquakes found that these precursory signals preceded the respective main shocks by 2-8 months. If correctly resolved, these deformation signals appear to record a rapid geodynamic process occurring deep within subduction zones and may be instrumental in the initiation of some megathrust earthquakes. While qualitative models have been proposed to explain the physical processes behind these potential precursory signals, such as an intra-slab extension, mineral phase changes, and large-scale fluid flow, numerical models exploring Earth’s geodynamic response to these processes have yet to be investigated.
Here, we use the finite element code Pylith to model geodynamic processes that plausibly occur deep within subduction zones, and that could produce the potential precursory signals observed. Given the high density of GNSS stations across Japan, we focus on the deformation preceding the 2011 Mw 9.0 Tohoku-Oki Earthquake. We model the intraslab extension and mineral phase change processes to obtain predicted surface displacements and compare those to GNSS observations of deformation prior to the earthquake. We explore how changes in rheological properties and subduction zone structure impact modeled predictions of surface displacement and gravity measurements for the tested geodynamic mechanisms. The model predictions and data comparisons will provide valuable insights into the plausibility of the proposed physical processes in generating the observed geodetic signatures. Furthermore, these models will help to establish how transient deformation deep within subduction zones may be expressed at Earth’s surface independent of their timing with respect to great earthquakes.
Session: From Geodynamics to Earthquake Rupture, Models That Cross Time- and Length-Scales [Poster Session]
Type: Poster
Date: 5/3/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Isis
Student Presenter: Yes
Invited Presentation:
Authors
Isis Lemus Presenting Author Corresponding Author ilemus@berkeley.edu University of California, Berkeley |
Curtis Baden c.w.baden@berkeley.edu University of California, Berkeley |
Kristel Chanard kristel.chanard@gmail.com Université de Paris |
Lei Wang wang.1115@osu.edu Ohio State University |
Roland Bürgmann burgmann@berkeley.edu University of California, Berkeley |
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Modeling the Proposed Deep Slab-Deformation Processes Behind Potential Precursory Signals Preceding Large Subduction Zone Earthquakes
Category
From Geodynamics to Earthquake Rupture, Models That Cross Time- and Length-Scales