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- Title
Bimodal seismicity in the Himalaya controlled by fault friction and geometry.
- Authors
Dal Zilio, Luca; van Dinther, Ylona; Gerya, Taras; Avouac, Jean-Philippe
- 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. There is increasing evidence that the seismicity of large Himalayan earthquakes can be bimodal, but the underlying mechanisms are unclear. Here, the authors present a model and show that the bimodal seismicity results from a relatively higher friction and a non-planar geometry of the Himalayan megathrust.
- Publication
Nature Communications, 2019, Vol 10, Issue 1, p1
- ISSN
2041-1723
- Publication type
Article
- DOI
10.1038/s41467-018-07874-8