Development of a Non-ergodic Ground Motion Model for the Groningen, Netherlands Region Based on a Hybrid Empirical and Simulation Dataset
Description:
We present a new non-ergodic ground motion model (GMM) for the Groningen natural gas field in the Netherlands, aimed at improving the region's seismic hazard characterization. Non-ergodic GMMs offer the ability to reduce aleatory variability, which often controls the seismic hazard, especially at longer return periods. This reduction, however, is accompanied by epistemic uncertainty in areas with sparse observations, while it shifts the median ground motion in regions with available recordings. To further constrain epistemic uncertainties, we conduct a series of 3D wave propagation simulations using a detailed 3D velocity model for Groningen. These simulations employ point sources to illuminate seismic wave paths absent in the empirical datasets.
We propagate ground motions up to a maximum usable frequency of 5 Hz by using a dense spectral element mesh and a modified Burne source time function to mitigate spatial aliasing. The non-ergodic GMM is based on a Gaussian Process Regression framework. We represent systematic source and site effects using isotropic kernels, while a new vector-integral kernel function is proposed to capture the systematic path effects. This kernel accounts for correlations along entire seismic rays, incorporating source and site locations, azimuthal dependence, while honoring reciprocity.
To handle large empirical and simulated datasets efficiently, we implement a sparse approximation of the precision matrix through a Kullback-Leibler (KL) divergence minimization. We estimate hyperparameters through a cross-correlation Kernel Flow scheme, which enhances model predictability for previously unobserved scenarios. Our formulation achieves a 40% reduction in aleatory variability, significantly improving the accuracy of seismic hazard assessments for Groningen.
Session: Challenges and Opportunities in Constraining Ground-motion Models from Physics-based Ground-motion Simulations - III
Type: Oral
Date: 4/17/2025
Presentation Time: 02:00 PM (local time)
Presenting Author: Grigorios
Student Presenter: No
Invited Presentation:
Poster Number:
Authors
Grigorios Lavrentiadis Presenting Author Corresponding Author glavrent@caltech.edu California Institute of Technology |
Elif Oral elifo@caltech.edu California Institute of Technology |
Domniki Asimaki domniki@caltech.edu California Institute of Technology |
|
|
|
|
|
|
Development of a Non-ergodic Ground Motion Model for the Groningen, Netherlands Region Based on a Hybrid Empirical and Simulation Dataset
Session
Challenges and Opportunities in Constraining Ground-motion Models from Physics-based Ground-motion Simulations