Does a damaged fault zone mitigate the near-field landslide risk during supershear earthquakes?—Application to the 2018 magnitude 7.5 Palu earthquake.

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Authors

Elif Oral , Huihui Weng , Jean-Paul Ampuero 

Abstract

The impact of earthquakes can be severely aggravated by cascading secondary hazards.
The 2018 Mw 7.5 Palu, Indonesia earthquake led to devastating tsunamis and landslides, while triggered submarine landslides possibly contributed substantially to generate the tsunami. The rupture was supershear over most of its length, but its speed was unexpectedly low, between the S-wave velocity Vs and Eshelby’s speed sqrt(Vs), an unstable speed range in conventional theory. Here, we investigate whether dynamic rupture models including a low-velocity fault zone (LVFZ) can reproduce such steady, slow supershear rupture. We then examine numerically how this peculiar feature of the Palu earthquake could have affected the near-field ground motion and thus the secondary hazards. Our findings suggest that the presence of a LVFZ can explain the slowness of the rupture and may have mitigated the near-field ground motion and induced landslides in Palu.

DOI

https://doi.org/10.31223/osf.io/5nugq

Subjects

Civil and Environmental Engineering, Earth Sciences, Engineering, Geotechnical Engineering, Physical Sciences and Mathematics

Keywords

Supershear rupture, Damaged fault zones, Dynamic rupture modelling, Earthquake-induced landslides, Seismic wave propagation

Dates

Published: 2019-10-03 12:05

Last Updated: 2019-10-06 18:55

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License

GNU Lesser General Public License (LGPL) 2.1

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