Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake Sequence
On 10 February 2021, an Mw 7.7 thrust earthquake ruptured the megathrust along the southeast Loyalty Islands within the strong bend in the plate boundary between the Australian plate and the North Fiji basin. The mainshock involved rupture with ∼50 s duration, with pure thrust slip concentrated in a...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Seismological Society of America
2021-12-01
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| Series: | The Seismic Record |
| Online Access: | https://doi.org/10.1785/0320210035 |
| _version_ | 1797358073141002240 |
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| author | Lingling Ye Wenzheng Gong Thorne Lay Hiroo Kanamori Xiaofei Chen |
| author_facet | Lingling Ye Wenzheng Gong Thorne Lay Hiroo Kanamori Xiaofei Chen |
| author_sort | Lingling Ye |
| collection | DOAJ |
| description | On 10 February 2021, an Mw 7.7 thrust earthquake ruptured the megathrust along the southeast Loyalty Islands within the strong bend in the plate boundary between the Australian plate and the North Fiji basin. The mainshock involved rupture with ∼50 s duration, with pure thrust slip concentrated in an east–west-trending slip patch with up to 4.2 m of slip extending from 10 to 25 km depth. Slip at depths <10 km is negligible on the curved fault surface, which conforms to the SLAB2 interface model. Static stress-drop estimates are ∼5.5 MPa, and the radiated energy is 2.38×10^15 J, with the moment-scaled value of 5.7×10^−6. The relatively shallow rupture from 10 to 25 km was moderately efficient in generating tsunami, with waves amplitudes up to 20 cm recorded in New Caledonia, New Zealand, Kermadec, and Fiji. Numerous M5+ normal-faulting aftershocks occur south of the trench, indicating effective stress change transfer from the megathrust to the bending flange of the Australian plate that is negotiating the bend in the trench. Highly productive sequences involving paired thrust and normal faulting have repeatedly occurred westward along the northwest-trending portion of the Loyalty Islands region, also indicating unusually efficient stress communication. |
| first_indexed | 2024-03-08T14:54:33Z |
| format | Article |
| id | doaj.art-9fd6cfefb57643fd8c89604a416d4cd3 |
| institution | Directory Open Access Journal |
| issn | 2694-4006 |
| language | English |
| last_indexed | 2024-03-08T14:54:33Z |
| publishDate | 2021-12-01 |
| publisher | Seismological Society of America |
| record_format | Article |
| series | The Seismic Record |
| spelling | doaj.art-9fd6cfefb57643fd8c89604a416d4cd32024-01-10T16:38:59ZengSeismological Society of AmericaThe Seismic Record2694-40062021-12-011315416310.1785/032021003521035Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake SequenceLingling Ye0https://orcid.org/0000-0001-9689-4149Wenzheng Gong1https://orcid.org/0000-0001-6078-3498Thorne Lay2https://orcid.org/0000-0003-2360-4213Hiroo Kanamori3https://orcid.org/0000-0001-8219-9428Xiaofei Chen4https://orcid.org/0000-0002-0950-8121Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, ChinaDepartment of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, ChinaDepartment of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California, U.S.A.Seismological Laboratory, California Institute of Technology, Pasadena, California, U.S.A.Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, ChinaOn 10 February 2021, an Mw 7.7 thrust earthquake ruptured the megathrust along the southeast Loyalty Islands within the strong bend in the plate boundary between the Australian plate and the North Fiji basin. The mainshock involved rupture with ∼50 s duration, with pure thrust slip concentrated in an east–west-trending slip patch with up to 4.2 m of slip extending from 10 to 25 km depth. Slip at depths <10 km is negligible on the curved fault surface, which conforms to the SLAB2 interface model. Static stress-drop estimates are ∼5.5 MPa, and the radiated energy is 2.38×10^15 J, with the moment-scaled value of 5.7×10^−6. The relatively shallow rupture from 10 to 25 km was moderately efficient in generating tsunami, with waves amplitudes up to 20 cm recorded in New Caledonia, New Zealand, Kermadec, and Fiji. Numerous M5+ normal-faulting aftershocks occur south of the trench, indicating effective stress change transfer from the megathrust to the bending flange of the Australian plate that is negotiating the bend in the trench. Highly productive sequences involving paired thrust and normal faulting have repeatedly occurred westward along the northwest-trending portion of the Loyalty Islands region, also indicating unusually efficient stress communication.https://doi.org/10.1785/0320210035 |
| spellingShingle | Lingling Ye Wenzheng Gong Thorne Lay Hiroo Kanamori Xiaofei Chen Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake Sequence The Seismic Record |
| title | Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake Sequence |
| title_full | Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake Sequence |
| title_fullStr | Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake Sequence |
| title_full_unstemmed | Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake Sequence |
| title_short | Shallow Megathrust Rupture during the 10 February 2021 Mw 7.7 Southeast Loyalty Islands Earthquake Sequence |
| title_sort | shallow megathrust rupture during the 10 february 2021 mw 7 7 southeast loyalty islands earthquake sequence |
| url | https://doi.org/10.1785/0320210035 |
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