Assessing Margin-Wide Rupture Behaviors along the  Cascadia Megathrust with 3-D Dynamic Rupture Simulations

This is a Preprint and has not been peer reviewed. This is version 2 of this Preprint.

Downloads

Download Preprint

Authors

Marlon Dale Ramos , Yihe Huang , Thomas Ulrich, Duo Li , Alice-Agnes Gabriel , Amanda Thomas

Abstract

From California to British Columbia, the Pacific Northwest coast bears an omnipresent earthquake and tsunami hazard from the Cascadia subduction zone. Multiple lines of evidence suggests that magnitude eight and greater megathrust earthquakes have occurred - the most recent being 321 years ago (i.e., 1700 A.D.). Outstanding questions for the next great megathrust event include where it will initiate, what conditions are favorable for rupture to span the convergent margin, and how much slip may be expected. We develop the first 3-D fully dynamic rupture simulations that are driven by fault stress, strength and friction to address these questions. The initial dynamic stress drop distribution in our simulations is constrained by geodetic coupling models, with segment locations taken from paleoseismic analyses. We document the sensitivity of nucleation location and stress drop to the final seismic moment and coseismic subsidence amplitudes. We find that the final earthquake size strongly depends on the amount of slip deficit in the central Cascadia region, which is inferred to be creeping interseismically, for a given initiation location in southern or northern Cascadia. Several simulations are also presented here that can closely approximate recorded coastal subsidence from the 1700 A.D. event without invoking localized high-stress asperities along the down-dip locked region of the megathrust. These results can be used to inform earthquake and tsunami hazards for not only Cascadia, but other subduction zones that have limited seismic observations but a wealth of geodetic inference.

DOI

https://doi.org/10.31223/X5SC8C

Subjects

Physical Sciences and Mathematics

Keywords

Seismology, Geophysics

Dates

Published: 2021-03-04 23:01

Last Updated: 2021-03-06 06:23

Older Versions
License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
Data is currently unavailable because the simulations must be reformatted for ease of access at the University of Michigan. Access to software and simulation parameters may be readily obtained from the manuscript itself.

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.