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Finite Source Properties of Large Strike-Slip Earthquakes

Atterholt, James and Ross, Zachary E. (2023) Finite Source Properties of Large Strike-Slip Earthquakes. . (Unpublished)

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Earthquake ruptures are complex physical processes that may vary with the structure and tectonics of the region in which they occur. Characterizing the factors controlling this variability would provide fundamental constraints on the physics of earthquakes and faults. We investigate this by determining finite source properties from 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 find that most strike-slip earthquakes have a large component of unilateral directivity, and many of these earthquakes show a mixture of unilateral and bilateral behavior. We also notice that oceanic intraplate earthquakes usually rupture a much larger width of the seismogenic zone than other strike-slip earthquakes, suggesting these earthquakes consistently breach the expected thermal boundary for oceanic ruptures. We also use these second moments to resolve nodal plane ambiguity for the large oceanic intraplate earthquakes and find that the rupture orientation is usually unaligned with encompassing fossil fracture zones.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Atterholt, James0000-0003-1603-5518
Ross, Zachary E.0000-0002-6343-8400
Additional Information:This work was partially funded by the National Science Foundation’s Graduate Research Fellowship Program (GRFP) with grant number DGE-1745301. The authors would like to thank Dr. Joann Stock for her insightful comments and suggestions regarding intraplate oceanic ruptures. The map shown in Figure 1 was created using The Generic Mapping Tools (GMT), version 6 (Wessel et al., 2019), which is available at The centroid moment tensor solutions used in this study are from the Global Centroid Moment Tensor (gCMT) catalog (Ekström et al., 2012) which is accessible online at The theoretical Green’s functions were computed using Salvus (Afanasiev et al., 2019), which is available at The waveform data in this study are from the Global Seismographic Network operated by both the Albuquerque Seismological Laboratory (IU: IRIS/USGS; (Albuquerque Seismological Laboratory (ASL)/USGS, 1988) and the Scripps Institution of Oceanography (II: IRIS/IDA; (Scripps Institution Of Oceanography, 1986). These waveforms may be accessed through the IRIS Data Management Center (DMC).
Group:Division of Geological and Planetary Sciences, Seismological Laboratory
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1745301
Record Number:CaltechAUTHORS:20230327-962779000.5
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:120419
Deposited By: George Porter
Deposited On:30 Mar 2023 14:36
Last Modified:30 Mar 2023 14:36

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