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Evaluating the Relationship Between Slip and Slip-velocity on Large-magnitude Ruptures Based on Surface Displacement

Description: 

Defining proper relationships between the dynamic parameters that govern the spatiotemporal evolution of a seismic rupture is a foundational step to constraining earthquake source modeling. The energy flux in the process zone balances how much energy is spent in the rupture growth and how much energy is radiated, among other physical processes involved in the rupture, such as the breaking and damage evolution of the source volume and diabatic processes. Thus, building baselines of the actual scaling of these parameters is a fundamental step to constrain rheology models for dynamic rupture simulations. In this study, we evaluate the relationship between the main outputs of dynamic rupture processes: slip, slip velocity and rupture velocity. We start by performing a set of dynamic simulations which shows that the total slip and maximum slip velocity are conceptually uncorrelated: the total slip is mainly related to global features of fault systems' geometry, whereas the slip velocity depends on the environmental stress and the dynamic process occurring in the process zone. We then use empirical data to explore these features by evaluating the correlation between surface fault displacement, a measured proxy for slip, and the Fourier amplitude of the wave field recorded at near-fault stations of four large-magnitude earthquakes that occurred in the past 25 years. Additionally, we estimated the arrival time of the rupture front from near-fault ground motion recordings with significant permanent fault displacement, allowing us to evaluate the relationship between the rupture velocity, slip and slip velocity. Surprisingly, our analysis shows that the fault displacement is not only non-correlated with the Fourier amplitude, but they exhibit an anti-correlation for frequencies above 0.3 Hz: regions of the rupture developing larger displacements radiate energy with weaker high-frequency content. Based on our findings, we proposed a model to constrain frequency-dependent near-fault ground-motion amplitudes for historical earthquakes based on paleoseismic displacement data for seismic hazard analysis applications.

Session: Challenges and Opportunities in Constraining Ground-motion Models from Physics-based Ground-motion Simulations [Poster]

Type: Poster

Date: 4/17/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Camilo Ignacio

Student Presenter: No

Invited Presentation: 

Poster Number: 47

Authors