Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling
The updip limit of the seismogenic zone of megathrusts is poorly understood. The relative absence of observed microseismicity in such regions, together with laboratory studies of friction, suggests that the shallow fault is mostly velocity strengthening, and likely to creep. Inversions of geodetic d...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/89817 http://hdl.handle.net/10220/46378 |
| _version_ | 1826116258055061504 |
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| author | Lindsey, Eric Ostrom Bradley, Kyle Hubbard, Judith Mallick, Rishav Hill, Emma Mary Almeida, Rafael |
| author2 | Asian School of the Environment |
| author_facet | Asian School of the Environment Lindsey, Eric Ostrom Bradley, Kyle Hubbard, Judith Mallick, Rishav Hill, Emma Mary Almeida, Rafael |
| author_sort | Lindsey, Eric Ostrom |
| collection | NTU |
| description | The updip limit of the seismogenic zone of megathrusts is poorly understood. The relative absence of observed microseismicity in such regions, together with laboratory studies of friction, suggests that the shallow fault is mostly velocity strengthening, and likely to creep. Inversions of geodetic data commonly show low to zero coupling at the trench, reinforcing this view. We show that the locked, downdip portion of the megathrust creates an updip stress shadow that prevents the shallow portion of the fault from creeping at a significant rate, regardless of its frictional behavior. Our models demonstrate that even if the shallowest 40% of the fault is frictionally unlocked, the expected creep at the fault tip is at most 30% of the plate rate, often within the uncertainties of surface geodetic measurements, and below current resolution of seafloor measurements. We conclude that many geodetic models significantly underestimate the degree of shallow coupling on megathrusts, and thus seismic and tsunami hazard. |
| first_indexed | 2024-10-01T04:08:23Z |
| format | Journal Article |
| id | ntu-10356/89817 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T04:08:23Z |
| publishDate | 2018 |
| record_format | dspace |
| spelling | ntu-10356/898172020-09-26T21:28:17Z Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling Lindsey, Eric Ostrom Bradley, Kyle Hubbard, Judith Mallick, Rishav Hill, Emma Mary Almeida, Rafael Asian School of the Environment Earth Observatory of Singapore Zero Coupling DRNTU::Science::Geology Megathrusts The updip limit of the seismogenic zone of megathrusts is poorly understood. The relative absence of observed microseismicity in such regions, together with laboratory studies of friction, suggests that the shallow fault is mostly velocity strengthening, and likely to creep. Inversions of geodetic data commonly show low to zero coupling at the trench, reinforcing this view. We show that the locked, downdip portion of the megathrust creates an updip stress shadow that prevents the shallow portion of the fault from creeping at a significant rate, regardless of its frictional behavior. Our models demonstrate that even if the shallowest 40% of the fault is frictionally unlocked, the expected creep at the fault tip is at most 30% of the plate rate, often within the uncertainties of surface geodetic measurements, and below current resolution of seafloor measurements. We conclude that many geodetic models significantly underestimate the degree of shallow coupling on megathrusts, and thus seismic and tsunami hazard. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version 2018-10-19T05:31:00Z 2019-12-06T17:34:09Z 2018-10-19T05:31:00Z 2019-12-06T17:34:09Z 2018 Journal Article Almeida, R., Lindsey, E. O., Bradley, K., Hubbard, J., Mallick, R., & Hill, E. M. (2018). Can the Updip Limit of Frictional Locking on Megathrusts Be Detected Geodetically? Quantifying the Effect of Stress Shadows on Near-Trench Coupling. Geophysical Research Letters, 45(10), 4754-4763. doi:10.1029/2018GL077785 0094-8276 https://hdl.handle.net/10356/89817 http://hdl.handle.net/10220/46378 10.1029/2018GL077785 en Geophysical Research Letters © 2018 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. 10 p. application/pdf |
| spellingShingle | Zero Coupling DRNTU::Science::Geology Megathrusts Lindsey, Eric Ostrom Bradley, Kyle Hubbard, Judith Mallick, Rishav Hill, Emma Mary Almeida, Rafael Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling |
| title | Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling |
| title_full | Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling |
| title_fullStr | Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling |
| title_full_unstemmed | Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling |
| title_short | Can the updip limit of frictional locking on megathrusts be detected geodetically? Quantifying the effect of stress shadows on near-trench coupling |
| title_sort | can the updip limit of frictional locking on megathrusts be detected geodetically quantifying the effect of stress shadows on near trench coupling |
| topic | Zero Coupling DRNTU::Science::Geology Megathrusts |
| url | https://hdl.handle.net/10356/89817 http://hdl.handle.net/10220/46378 |
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