Bimodal seismicity in the Himalaya controlled by fault friction and geometry
Abstract
There is increasing evidence that the Himalayan seismicity can be bimodal: blind earthquakes (up to Mw ~ 7.8) tend to cluster in the downdip part of the seismogenic zone, whereas infrequent great earthquakes (Mw 8+) propagate up to the Himalayan frontal thrust. To explore the causes of this bimodal seismicity, we developed a two-dimensional, seismic cycle model of the Nepal Himalaya. Our visco-elasto-plastic simulations reproduce important features of the earthquake cycle, including interseismic strain and a bimodal seismicity pattern. Bimodal seismicity emerges as a result of relatively higher friction and a non-planar geometry of the Main Himalayan Thrust fault. This introduces a region of large strength excess that can only be activated once enough stress is transferred upwards by blind earthquakes. This supports the view that most segments of the Himalaya might produce complete ruptures significantly larger than the 2015 Mw 7.8 Gorkha earthquake, which should be accounted for in future seismic hazard assessments.
Additional Information
© 2018 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received 05 April 2018; Accepted 30 November 2018; Published 03 January 2019. This study was funded by the SNF 2-77090-14 project Swiss-AlpArray SINERGIA. We gratefully acknowledge A.A. Gabriel, E. Kissling, J.-P. Ampuero, L. Bollinger, R. Jolivet, G. Hetényi, R. Almeida, S. Barbot and the STM-group for comments. V.L. Stevens kindly provided the coupling data. We are grateful to J. Singer for providing us with a basic GMT script to plot Fig. 1a. Numerical simulations were performed on ETH cluster Euler. Code availability: Computer code used within the manuscript and its Supplementary Information are available from the corresponding author upon reasonable request. Data availability: Data within the manuscript and its Supplementary Information are available from the corresponding author upon reasonable request. Author Contributions: L.D.Z. designed the study and model setup, carried out and analysed the numerical experiments, and wrote the paper. Y.v.D. and T.G. developed the STM methodology and analysed the results. J.-P.A. contributed to the concept development. All authors discussed the results and commented on the paper. The authors declare no competing interests.Attached Files
Published - s41467-018-07874-8.pdf
Supplemental Material - 41467_2018_7874_MOESM1_ESM.pdf
Supplemental Material - 41467_2018_7874_MOESM2_ESM.pdf
Supplemental Material - 41467_2018_7874_MOESM3_ESM.pdf
Supplemental Material - 41467_2018_7874_MOESM4_ESM.mp4
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Additional details
- PMCID
- PMC6318329
- Eprint ID
- 92101
- Resolver ID
- CaltechAUTHORS:20190107-082842022
- Swiss National Science Foundation (SNSF)
- 2-77090-14
- Created
-
2019-01-07Created from EPrint's datestamp field
- Updated
-
2022-02-24Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory, Division of Geological and Planetary Sciences (GPS)