| Title | The mechanism of partial rupture of a locked megathrust: The role of fault morphology |
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| Author | Qiu, Q; Hill, E M; Barbot, S; Hubbard, J; Feng, W ; Lindsey, E O; Feng, L; Dai, K; Samsonov, S V; Tapponnier, P |
| Source | Geology vol. 44, no. 10, 2016 p. 875-878, https://doi.org/10.1130/G38178.1  Open Access |
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| Year | 2016 |
| Alt Series | Natural Resources Canada, Contribution Series 20170208 |
| Publisher | Geological Society of America |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Gorkha; Kathmandu; Nepal |
| Lat/Long WENS | 84.0000 86.0000 28.0000 27.0000 |
| Subjects | earthquakes; geodesy; seismicity; health hazards; faults; faults, thrust; modelling |
| Illustrations | location maps; graphs; 3-D models |
| Released | 2016 08 31 |
| Abstract | Assessment of seismic hazard relies on estimates of how large an area of a tectonic fault could potentially rupture in a single earthquake.
Vital information for these forecasts includes which areas
of a fault are locked and how the fault is segmented. Much research has focused on exploring downdip limits to fault rupture from chemical and thermal boundaries, and along-strike barriers from subducted structural features, yet we regularly see only
partial rupture of fully locked fault patches that could have ruptured as a whole in a larger earthquake. Here we draw insight into this conundrum from the 25 April 2015 Mw 7.8 Gorkha (Nepal) earthquake. We invert geodetic data with a structural
model of the Main Himalayan thrust in the region of Kathmandu, Nepal, showing that this event was generated by rupture of a décollement bounded on all sides by more steeply dipping ramps. The morphological bounds explain why the event ruptured only a
small piece of a large fully locked seismic gap. We then use dynamic earthquake cycle modeling on the same fault geometry to reveal that such events are predicted by the physics. Depending on the earthquake history and the details of rupture
dynamics, however, great earthquakes that rupture the entire seismogenic zone are also possible. These insights from Nepal should be applicable to understanding bounds on earthquake size on megathrusts worldwide. |
| GEOSCAN ID | 305978 |
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