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Global Evaluation of Large Strike-Slip Ruptures Using a Bayesian Estimation of Stress Glut Second Moments

Description: 

Earthquake ruptures are complex processes that may vary with the structure and tectonics of the region in which they occur. Characterizing this potential variability may yield fundamental insights into how fault zones control how earthquakes happen. We investigate this by determining second moments of the stress glut for a global dataset of large strike-slip earthquakes. Our approach uses a Bayesian inverse formulation with teleseismic body and surface waves, which yields a low-dimensional probabilistic description of rupture properties including spatial extent, directivity, and duration. This technique is useful for comparing events, because it makes only minor geometric constraints, avoids bias due to rupture velocity parameterization, and yields a full ensemble of possible solutions given the uncertainties of the data. We apply this framework to all great strike-slip earthquakes of the past three decades, and we use the resultant second moments to compare source quantities like directivity ratio, rectilinearity, stress drop, and depth extent. We also use these second moments to resolve nodal plane ambiguity for oceanic intraplate earthquakes. We find that most strike-slip earthquakes have a large component of unilateral directivity, oceanic intraplate earthquakes usually rupture much deeper than other strike-slip earthquakes, and the strikes of oceanic intraplate earthquakes usually do not align with encompassing fossil fracture zones.

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: James Atterholt

Student Presenter: Yes

Invited Presentation: 

Authors