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Plate‐boundary kinematics of the Afrera linkage zone (Afar) from InSAR and seismicity

Plate‐boundary kinematics of the Afrera linkage zone (Afar) from InSAR and seismicity
Plate‐boundary kinematics of the Afrera linkage zone (Afar) from InSAR and seismicity
Studying the mechanisms of interaction between rift segments is key to understanding the kinematics of plate boundaries in continental rifts. However, the spatial and temporal evolution of deformation at rift linkage zones is rarely observed directly. Here we combine InSAR data spanning 2005‐2010 and 2014‐2019 from ENVISAT and Sentinel‐1 satellites, respectively, with local seismicity from the Afar rift to investigate the plate‐boundary kinematics of the Afrera linkage zone, the junction between the Erta Ale and Tat Ali magmatic segments in Northern Afar (Ethiopia). We obtain time‐series of cumulative InSAR Line‐Of‐Sight displacements that show deformation is accommodated by a series of active en‐echelon faults striking ∼NS and characterized by normal slip associated with a left‐lateral strike‐slip component. Additionally, we observe spatial variation in faults behavior with stick‐slip and creep. The faults in the center of the linkage zone behave primarily in a stick‐slip mode (with abrupt fault displacements up to ∼40 mm) and fault motions are associated with earthquakes of ML > 5. Conversely, faults at the edge of the linkage zone, near the magmatic segments, show creep and some stick‐slip behavior (with cumulative LOS displacement up to ∼30‐40 mm over a ∼5 years period) accompanied by low‐level seismicity. Some of the creeping faults are also spatially associated with hydrothermal springs. We interpret that the temporal behavior of the faults in the linkage zone is controlled by the interplay between tectonic extension, high heat flows and fluid circulation near the magmatic segments where creeping of some faults is favored.
Afar, InSAR, rift linkage, seismicity, time-series
2169-9356
La Rosa, Alessandro
3443c440-23fe-437e-b908-80f6b923c4ba
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Wang, Hua
d2464222-af0f-49da-a6bb-8770dc1f0b11
Doubre, Cecile
9f348925-f5b6-445c-8663-7f58f58b97f3
Leroy, Sylvie
627c503b-1036-41fc-a24c-3d09954fab0a
Sani, Federico
6c59b4c4-ecca-4ecc-ba2c-66efa5e5e3df
Corti, Giacomo
dce88b12-5b7a-43b1-8a58-5bd1bc13634c
Ayele, Atalay
5b4eeb35-d229-4325-8940-d934dab7563d
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
La Rosa, Alessandro
3443c440-23fe-437e-b908-80f6b923c4ba
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Wang, Hua
d2464222-af0f-49da-a6bb-8770dc1f0b11
Doubre, Cecile
9f348925-f5b6-445c-8663-7f58f58b97f3
Leroy, Sylvie
627c503b-1036-41fc-a24c-3d09954fab0a
Sani, Federico
6c59b4c4-ecca-4ecc-ba2c-66efa5e5e3df
Corti, Giacomo
dce88b12-5b7a-43b1-8a58-5bd1bc13634c
Ayele, Atalay
5b4eeb35-d229-4325-8940-d934dab7563d
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65

La Rosa, Alessandro, Pagli, Carolina, Wang, Hua, Doubre, Cecile, Leroy, Sylvie, Sani, Federico, Corti, Giacomo, Ayele, Atalay and Keir, Derek (2021) Plate‐boundary kinematics of the Afrera linkage zone (Afar) from InSAR and seismicity. Journal of Geophysical Research: Solid Earth, 126 (5), [e2020JB021387]. (doi:10.1029/2020JB021387).

Record type: Article

Abstract

Studying the mechanisms of interaction between rift segments is key to understanding the kinematics of plate boundaries in continental rifts. However, the spatial and temporal evolution of deformation at rift linkage zones is rarely observed directly. Here we combine InSAR data spanning 2005‐2010 and 2014‐2019 from ENVISAT and Sentinel‐1 satellites, respectively, with local seismicity from the Afar rift to investigate the plate‐boundary kinematics of the Afrera linkage zone, the junction between the Erta Ale and Tat Ali magmatic segments in Northern Afar (Ethiopia). We obtain time‐series of cumulative InSAR Line‐Of‐Sight displacements that show deformation is accommodated by a series of active en‐echelon faults striking ∼NS and characterized by normal slip associated with a left‐lateral strike‐slip component. Additionally, we observe spatial variation in faults behavior with stick‐slip and creep. The faults in the center of the linkage zone behave primarily in a stick‐slip mode (with abrupt fault displacements up to ∼40 mm) and fault motions are associated with earthquakes of ML > 5. Conversely, faults at the edge of the linkage zone, near the magmatic segments, show creep and some stick‐slip behavior (with cumulative LOS displacement up to ∼30‐40 mm over a ∼5 years period) accompanied by low‐level seismicity. Some of the creeping faults are also spatially associated with hydrothermal springs. We interpret that the temporal behavior of the faults in the linkage zone is controlled by the interplay between tectonic extension, high heat flows and fluid circulation near the magmatic segments where creeping of some faults is favored.

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2020JB021387 - Accepted Manuscript
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e-pub ahead of print date: 7 April 2021
Keywords: Afar, InSAR, rift linkage, seismicity, time-series

Identifiers

Local EPrints ID: 448962
URI: http://eprints.soton.ac.uk/id/eprint/448962
ISSN: 2169-9356
PURE UUID: c2e89e31-5466-4293-b3b0-5af99c89ee6c
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 12 May 2021 16:30
Last modified: 09 Jun 2021 01:43

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Contributors

Author: Alessandro La Rosa
Author: Carolina Pagli
Author: Hua Wang
Author: Cecile Doubre
Author: Sylvie Leroy
Author: Federico Sani
Author: Giacomo Corti
Author: Atalay Ayele
Author: Derek Keir ORCID iD

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