Insights From Distinct Element Method Models on Fault Scarp Morphology in Thrust and Reverse Fault Earthquakes.
Description:
We seek to better understand and forecast the near-surface coseismic deformation that occurs as a result of large magnitude thrust and reverse fault earthquakes using geomechanical models. We developed a distinct element method (DEM) model to evaluate the physical processes that control the pattern of ground surface ruptures on thrust and reverse faults. In prior work, we used 45 initial 2D DEM models to develop a classification system for fault scarp morphology (monoclinal, pressure ridge, and simple scarps) each of which can subsequently modified by hanging wall collapse. These relationships are supported by natural rupture patterns from recent and paleo-earthquakes across a range of geologic settings. In this next phase of our study, we tested a suite of 3,425 2D DEM experiments in dense, medium-dense, and loose sediment in a model 50 m wide with 3, 5, and 10 m of sediment depth. These models include homogeneous and heterogeneous sediment mechanics, a range of fault dips (20 – 70º), and displacements of up to 5 m. We used a machine learning model (based on computer vision) to take measurements of the DEM experiments every 5 cm of slip on the fault at depth. This resulted in ~250,000 measurements of the homogeneous DEM models, which enabled robust statistical relationships between model parameters (slip, fault dip, sediment strength, and sediment depth) with the observed surface deformation characteristics (scarp height, width, and dip as well as the tendency to form backthrusts and secondary fault splays). These relationships are supported by natural rupture patterns from recent and paleo-earthquakes across a range of geologic settings. In conjunction with these natural examples, our models provide a basis to more accurately forecast ground surface deformation characteristics that will result from future earthquakes based on limited information about the earthquake source and local sediment properties.
Session: Assessing Seismic Hazard for Critical Facilities and Infrastructure – Insights and Challenges [Poster Session]
Type: Poster
Date: 5/3/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Kristen
Student Presenter: Yes
Invited Presentation:
Authors
Kristen Chiama Presenting Author Corresponding Author kchiama@g.harvard.edu Harvard University |
William Bednarz william_bednarz@brown.edu Brown University |
Robb Moss rmoss@calpoly.edu California Polytechnic State University, San Luis Obispo |
John Shaw shaw@eps.harvard.edu Harvard University |
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Insights From Distinct Element Method Models on Fault Scarp Morphology in Thrust and Reverse Fault Earthquakes.
Category
Assessing Seismic Hazard for Critical Facilities and Infrastructure – Insights and Challenges