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Tonga Slab Morphology and Stress Variations Controlled by a Relic Slab: Implications for Deep Earthquakes in the Tonga‐Fiji Region

Liu, Hao and Gurnis, Michael and Leng, Wei and Jia, Zhe and Zhan, Zhongwen (2021) Tonga Slab Morphology and Stress Variations Controlled by a Relic Slab: Implications for Deep Earthquakes in the Tonga‐Fiji Region. Geophysical Research Letters, 48 (7). Art. No. e2020GL091331. ISSN 0094-8276. doi:10.1029/2020gl091331. https://resolver.caltech.edu/CaltechAUTHORS:20210323-070959264

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Abstract

Deep focus earthquakes within the Tonga‐Fiji subduction system account for about two‐thirds of the global total and provide significant constraints on slab deformation. The factors controlling the intense deformation remain unclear. Here, we use two‐dimensional, time‐dependent geodynamic models to study the morphology, stress state, and thermal structure of the Tonga‐Fiji subduction zone. The results, consistent with tomographic images and focal mechanisms, demonstrate that collision between a relic slab from the Vanuatu Trench and the Tonga slab may control the steeper dip of the Tonga slab and earthquakes in the mantle transition zone. We suggest that the magnitude 8.2 and 7.9 earthquakes in 2018 mostly ruptured within the warm rim of the Tonga slab and occurred beneath the folding relic slab with high temperatures of at least ∼900°C and ∼1100°C, respectively. The findings support the hypothesis that local slab temperature likely controls rupture of deep earthquakes.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2020gl091331DOIArticle
https://geodynamics.org/cigRelated ItemCode
https://www.earth.ox.ac.uk/~smachine/cgi/index.phpRelated ItemCode
ORCID:
AuthorORCID
Liu, Hao0000-0002-3200-5215
Gurnis, Michael0000-0003-1704-597X
Leng, Wei0000-0002-7979-4100
Jia, Zhe0000-0002-2484-3550
Zhan, Zhongwen0000-0002-5586-2607
Additional Information:© 2021 American Geophysical Union. Issue Online: 09 April 2021; Version of Record online: 09 April 2021; Accepted manuscript online: 22 March 2021; Manuscript accepted: 07 March 2021; Manuscript revised: 08 February 2021; Manuscript received: 19 October 2020. H. Liu's visit to Caltech was supported by the Strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB 41000000 and the China Scholarship Council. Additional support provided by the National Science Foundation through award EAR‐1645775, and National Natural Science Foundation of China (41774105 and 41820104004). Data Availability Statement: The mantle convection code Citcom and the P wave tomography models are available at https://geodynamics.org/cig/and https://www.earth.ox.ac.uk/∼smachine/cgi/index.php, while model data files will be available at https://data.caltech.edu/
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Chinese Academy of SciencesXDB 41000000
China Scholarship CouncilUNSPECIFIED
NSFEAR-1645775
National Natural Science Foundation of China41774105
National Natural Science Foundation of China41820104004
Subject Keywords:deep earthquakes; relic slab; stress variations; thermal structure; Tonga slab
Issue or Number:7
DOI:10.1029/2020gl091331
Record Number:CaltechAUTHORS:20210323-070959264
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210323-070959264
Official Citation:Liu, H., Gurnis, M., Leng, W., Jia, Z., & Zhan, Z. (2021). Tonga slab morphology and stress variations controlled by a relic slab: Implications for deep earthquakes in the Tonga‐Fiji region. Geophysical Research Letters, 48, e2020GL091331. https://doi.org/10.1029/2020GL091331
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108522
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:23 Mar 2021 17:21
Last Modified:09 Apr 2021 20:14

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