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Extensional earthquakes in the absence of magma in northern Afar: insights from InSAR

Extensional earthquakes in the absence of magma in northern Afar: insights from InSAR
Extensional earthquakes in the absence of magma in northern Afar: insights from InSAR
In magma-rich rifts, normal faulting is commonly thought to be induced by dike intrusions. However, whether fault slip occurs purely tectonically is unclear. An earthquake sequence starting with a Mw 5.5 earthquake occurred in December 2022 in northern Afar, a continental rift near breakup. InSAR measurements show that seismicity was caused by normal faulting alone, without involvement of magma movements. Our best-fit InSAR models show that conjugate faults ruptured during the seismic sequence with mainly normal dip-slip and total deformation corresponding to a Mw 5.7 event, in agreement with local seismic recordings. Our models show that tectonic faulting accommodates 26 cm of extension corresponding to ∼30 years of plate spreading without any link to magma. Our observations point toward significant along-rift variation in the proportion of extension from faulting, potentially caused by along-rift variations in rate of extension and/or from a spatially and temporally segmented supply of magma.
Afar, InSAR, earthquakes, rift margins
0094-8276
La Rosa, Alessandro
3443c440-23fe-437e-b908-80f6b923c4ba
Raggiunti, Martina
c9bb1c87-dabf-4c37-a3de-9fa0b4ef0de2
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Wang, Hua
d2464222-af0f-49da-a6bb-8770dc1f0b11
Ayele, Atalay
730f62fb-c461-4a4e-b52d-b143a7936df6
La Rosa, Alessandro
3443c440-23fe-437e-b908-80f6b923c4ba
Raggiunti, Martina
c9bb1c87-dabf-4c37-a3de-9fa0b4ef0de2
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Wang, Hua
d2464222-af0f-49da-a6bb-8770dc1f0b11
Ayele, Atalay
730f62fb-c461-4a4e-b52d-b143a7936df6

La Rosa, Alessandro, Raggiunti, Martina, Pagli, Carolina, Keir, Derek, Wang, Hua and Ayele, Atalay (2023) Extensional earthquakes in the absence of magma in northern Afar: insights from InSAR. Geophysical Research Letters, 50 (10), [e2023GL102826]. (doi:10.1029/2023GL102826).

Record type: Article

Abstract

In magma-rich rifts, normal faulting is commonly thought to be induced by dike intrusions. However, whether fault slip occurs purely tectonically is unclear. An earthquake sequence starting with a Mw 5.5 earthquake occurred in December 2022 in northern Afar, a continental rift near breakup. InSAR measurements show that seismicity was caused by normal faulting alone, without involvement of magma movements. Our best-fit InSAR models show that conjugate faults ruptured during the seismic sequence with mainly normal dip-slip and total deformation corresponding to a Mw 5.7 event, in agreement with local seismic recordings. Our models show that tectonic faulting accommodates 26 cm of extension corresponding to ∼30 years of plate spreading without any link to magma. Our observations point toward significant along-rift variation in the proportion of extension from faulting, potentially caused by along-rift variations in rate of extension and/or from a spatially and temporally segmented supply of magma.

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Geophysical Research Letters - 2023 - La Rosa - Extensional Earthquakes in the Absence of Magma in Northern Afar Insights - Version of Record
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Accepted/In Press date: 2 May 2023
e-pub ahead of print date: 11 June 2023
Additional Information: Funding Information: ALR, CP, DK, MR are supported by Ministero dell’Universita e della Ricerca (MiUR) through PRIN Grant 2017P9AT72. HW is supported by the National Natural Science Foundation of China (42274001). Publisher Copyright: © 2023. The Authors.
Keywords: Afar, InSAR, earthquakes, rift margins

Identifiers

Local EPrints ID: 477819
URI: http://eprints.soton.ac.uk/id/eprint/477819
ISSN: 0094-8276
PURE UUID: f112c52a-cef8-44d4-a2c6-7f4da6b40a59
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 15 Jun 2023 16:45
Last modified: 06 Jun 2024 01:49

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Contributors

Author: Alessandro La Rosa
Author: Martina Raggiunti
Author: Carolina Pagli
Author: Derek Keir ORCID iD
Author: Hua Wang
Author: Atalay Ayele

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