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Evaluating the Impact of 3D Fault Geometry on Surface Rupture Probabilities Using Earthquake-cycle Simulations

Description: 

Surface rupture and deformation are common processes during large earthquakes, often worsening damage caused by ground shaking. The ongoing growth of urban areas and the expansion of critical infrastructure—such as dams, power plants, and lifelines—near seismically active faults increase exposure to earthquake ruptures and amplify seismic risk. Consequently, quantifying surface rupture probabilities and related hazard in active regions has become a key focus in fault displacement hazard analyses (FDHA). Despite this, a primary challenge for FDHA, especially in slower deforming regions, is the limited availability of surface rupture records needed for robust statistical analyses. These records are often insufficient to characterize the long-term, seismic cycle-scale behavior of fault systems, ultimately limiting forecasting capabilities.

In this study, we adopt a novel approach to estimate surface rupture probabilities by analyzing simulated earthquake ruptures generated with the RSQSim earthquake cycle simulator at the Monte Vettore Fault System (MVFS) in Central Italy. Following benchmarking tests to select rate-and-state parameters that best match empirical relationships, we simulate 100 kyr-long earthquake catalogs using three distinct 3D fault geometry models for the MVFS. These models incorporate variations in fault dip—constant and listric—and segment connectivity at depth, employing a detailed fault discretization (~150 m elements) to capture the complexity of mapped fault traces. We evaluate the impact of these geometries on surface fault rupture probabilities, and we discuss their feasibility by comparing simulated cumulative throw and earthquake recurrence intervals at surface locations against geomorphic and paleoseismic records, as well as empirical regressions of rupture probabilities from the literature. This approach highlights the potential of earthquake cycle simulations to improve FDHA and provides insights into the long-term behavior of geometrically complex fault systems and their surface rupturing potential.

Session: Testing, Testing 1 2 3: Appropriate Evaluation of New Seismic Hazard and Risk Models - I

Type: Oral

Date: 4/15/2025

Presentation Time: 08:15 AM (local time)

Presenting Author: Bruno

Student Presenter: No

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