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Quantifying Uncertainties in Earthquake Source Models: Implications of Slip Distribution Variations and Fault Parameters on Ground Motion Studies

Description: 

Accurate prediction of ground motion is important for seismic hazard assessments. One important aspect of ground motion prediction is understanding the uncertainties in earthquake source models, particularly those related to the choice of slip distributions and fault parameters. Here, we quantify such uncertainties. Some models assume that the k-square slip distribution will produce the omega-square spectral shape of radiation. This assumption is based on a point-source geometry and an instantaneous fault motion. To test this assumption, we solve the representation integral of elasticity, which allows us to isolate important physical parameters of faulting and their effects on the entire relevant frequency range. By applying a kinematic approach, we can prescribe a finite-fault geometry considering a non-instantaneous fault motion. This approach reveals variations in the slopes of the spectra generated by the k-square slip distributions varying between -6 and -3.5. This contrasts with the expected slope of -2 resulting from the omega- square spectral shape. We produce the same spectral shape independent on the modeled slip distribution (k-square or random). Density plots were used to visualize the slip distributions across the fault plane, revealing heterogeneity and showing fault complexity. The k-square slip distribution proves effective in identifying consistent patterns of amplitude distributions across different frequencies making it valuable for theoretical investigations. In contrast, randomized slip distributions provide a comprehensive range of variations, enhancing our understanding of complex fault behaviors. Furthermore, we explore the effect of hypocenter position on the spectral shape, revealing that variations in hypocenter location significantly influence the frequency content of the seismic waves. Our findings show that the choice of slip distribution model does not constrain the spectral shape outcomes, as both k-square and randomized models yield similar spectral characteristics when accounting for finite-fault geometry and other fault parameters.

Session: Recent Advances in Modeling Near-source Ground Motions for Seismic Hazard Applications [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Elizabeth

Student Presenter: Yes

Invited Presentation: 

Poster Number: 57

Authors