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Epistemic Uncertainties in Seismic Source Modeling for Finite-fault Ground-motion Simulations

Description: 

Modern Probabilistic Seismic Hazard Assessment (PSHA) increasingly requires finite-fault ground-motion simulations, in particular for critical facilities, to either augment existing databases of recorded ground-motions (in magnitude-distance ranges of limited or missing data) or to generate ground-motion time-series for specific scenarios of interest and importance. To capture the epistemic uncertainties in seismic source modeling for finite-fault ground-motion simulations, three key components have to be considered: (1) modeling and parameterizing seismic-wave propagation; (2) modeling and parameterizing fault geometry and fault segmentation; (3) modeling and parameterizing the spatio-temporal earthquake rupture process. I refer to these components as Step 1-3, as they are typically considered in this sequence. A fourth component, local site effects, is not subject of this contribution.

In this presentation, I first briefly summarize the key ingredients (geological and physical parameters) to be defined. Next, I succinctly review the most common computational methods in use for conducting finite-fault ground-motions simulations for PSHA purposes. The goal is to identify corresponding epistemic uncertainties and to aggregrate these into a general logic-tree structure to be used in PSHA for critical facilities. Given the resulting and rather complicated logic-tree, admissible simplifications in the logic-tree structure need to be developed, i.e. acceptable short-cuts given the geological and seismotectonic boundary conditions and knowledge for a given site. My talk concludes with discussing the question of how many finite-fault ground-motion simulations may be needed to adequately quantify epistemic ground-motion uncertainty.

Session: Challenges and Opportunities in Constraining Ground-motion Models from Physics-based Ground-motion Simulations - I

Type: Oral

Date: 4/17/2025

Presentation Time: 08:30 AM (local time)

Presenting Author: Paul Martin

Student Presenter: No

Invited Presentation: Yes

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