Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra
Geometry and frictional states of the megathrust in subduction zones play critical roles on the rupture extent, hence the magnitude, of great earthquakes. However, their details are often difficult to obtain, primarily due to limited offshore geophysical observations. Here we overcome this challenge...
| Main Authors: | , , , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/179231 |
| _version_ | 1811677689631735808 |
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| author | Wang, Xin Wei, Shengji Morales-Yáñez, Catalina Duputel, Zacharie Chen, Ling Hao, Tianyao Zhao, Liang |
| author2 | Asian School of the Environment |
| author_facet | Asian School of the Environment Wang, Xin Wei, Shengji Morales-Yáñez, Catalina Duputel, Zacharie Chen, Ling Hao, Tianyao Zhao, Liang |
| author_sort | Wang, Xin |
| collection | NTU |
| description | Geometry and frictional states of the megathrust in subduction zones play critical roles on the rupture extent, hence the magnitude, of great earthquakes. However, their details are often difficult to obtain, primarily due to limited offshore geophysical observations. Here we overcome this challenge by precisely determining source parameters (i.e., location and focal mechanism) of medium-sized earthquakes using global broadband seismic waveform data. The dip angles of 108 Mw 5.0+ plate interface events from 1990 to 2017 in the central Sumatran subduction zone are tightly constrained by waveform inversion, and their locations are refined with surface-wave relocation and depth phases modeling. Our results reveal compact trench parallel earthquake belts at the up-dip and down-dip boundaries of the ruptures of the Mentawai 2007 Mw 8.4 and Mw 7.9 earthquakes. The down-dip seismicity belt marks ∼8º bending of the plate interface, suggesting that the change of fault geometry may have played a role in halting the megathrust rupture along with thermal effects. The up-dip seismicity belt shows a clear spatial complementarity to the largest events’ slip distribution. This belt is quite narrow (∼20 km) for the Mw 8.4 rupture but much broader (∼50 km) for the Mw 7.9 event. The combination of the up-dip seismicity belt and slip distributions matches well with the positive residual bathymetry and gravity anomalies, suggesting that these events resulted from long-term coupling on the plate boundary. Our findings suggest the importance of considering both up-dip and down-dip seismicity belts, along with residual bathymetry and gravity data, in understanding megathrust rupture behaviors and assessing the associated hazards. |
| first_indexed | 2024-10-01T02:41:22Z |
| format | Journal Article |
| id | ntu-10356/179231 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T02:41:22Z |
| publishDate | 2024 |
| record_format | dspace |
| spelling | ntu-10356/1792312024-07-23T05:24:10Z Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra Wang, Xin Wei, Shengji Morales-Yáñez, Catalina Duputel, Zacharie Chen, Ling Hao, Tianyao Zhao, Liang Asian School of the Environment Earth Observatory of Singapore Earth and Environmental Sciences Slab geometry Earthquake source parameters Geometry and frictional states of the megathrust in subduction zones play critical roles on the rupture extent, hence the magnitude, of great earthquakes. However, their details are often difficult to obtain, primarily due to limited offshore geophysical observations. Here we overcome this challenge by precisely determining source parameters (i.e., location and focal mechanism) of medium-sized earthquakes using global broadband seismic waveform data. The dip angles of 108 Mw 5.0+ plate interface events from 1990 to 2017 in the central Sumatran subduction zone are tightly constrained by waveform inversion, and their locations are refined with surface-wave relocation and depth phases modeling. Our results reveal compact trench parallel earthquake belts at the up-dip and down-dip boundaries of the ruptures of the Mentawai 2007 Mw 8.4 and Mw 7.9 earthquakes. The down-dip seismicity belt marks ∼8º bending of the plate interface, suggesting that the change of fault geometry may have played a role in halting the megathrust rupture along with thermal effects. The up-dip seismicity belt shows a clear spatial complementarity to the largest events’ slip distribution. This belt is quite narrow (∼20 km) for the Mw 8.4 rupture but much broader (∼50 km) for the Mw 7.9 event. The combination of the up-dip seismicity belt and slip distributions matches well with the positive residual bathymetry and gravity anomalies, suggesting that these events resulted from long-term coupling on the plate boundary. Our findings suggest the importance of considering both up-dip and down-dip seismicity belts, along with residual bathymetry and gravity data, in understanding megathrust rupture behaviors and assessing the associated hazards. This research was supported by the National Key R&D Program of China (2022YFF0802600), Singapore MOE2019-T2-1-182(S) and MOEMOET32021–0002, Chile FONDECYT 3220307, and the Key Research Program of the Institute of Geology and Geophysics, Chinese Academy of Sciences No. IGGCAS-201904. 2024-07-23T05:24:10Z 2024-07-23T05:24:10Z 2024 Journal Article Wang, X., Wei, S., Morales-Yáñez, C., Duputel, Z., Chen, L., Hao, T. & Zhao, L. (2024). Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra. Earth and Planetary Science Letters, 637, 118726-. https://dx.doi.org/10.1016/j.epsl.2024.118726 0012-821X https://hdl.handle.net/10356/179231 10.1016/j.epsl.2024.118726 2-s2.0-85191662155 637 118726 en MOE2019-T2-1-182(S) MOE-MOET32021-0002 Earth and Planetary Science Letters © 2024 Published by Elsevier B.V. All rights reserved. |
| spellingShingle | Earth and Environmental Sciences Slab geometry Earthquake source parameters Wang, Xin Wei, Shengji Morales-Yáñez, Catalina Duputel, Zacharie Chen, Ling Hao, Tianyao Zhao, Liang Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra |
| title | Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra |
| title_full | Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra |
| title_fullStr | Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra |
| title_full_unstemmed | Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra |
| title_short | Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra |
| title_sort | plate interface geometry complexity and persistent heterogenous coupling revealed by a high resolution earthquake focal mechanism catalog in mentawai sumatra |
| topic | Earth and Environmental Sciences Slab geometry Earthquake source parameters |
| url | https://hdl.handle.net/10356/179231 |
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