The University of Southampton
University of Southampton Institutional Repository

Depth extent and kinematics of faulting in the southern Tanganyika rift, Africa

Depth extent and kinematics of faulting in the southern Tanganyika rift, Africa
Depth extent and kinematics of faulting in the southern Tanganyika rift, Africa
Unusually deep earthquakes occur beneath rift segments with and without surface expressions of magmatism in the East African Rift system (EARS). The Tanganyika rift is part of the Western rift and has no surface evidence of magmatism. The TANG14 array was deployed in the southern Tanganyika rift, where earthquakes of magnitude up to 7.4 have occurred, to probe crust and upper mantle structure and evaluate fault kinematics. 474 earthquakes detected between June 2014 and September 2015 are located using a new regional velocity model. The precise locations, magnitudes and source mechanisms of local and teleseismic earthquakes are used to determine seismogenic layer thickness, delineate active faults, evaluate regional extension direction, and evaluate kinematics of border faults. The active faults span more than 350 km with deep normal faults transecting the thick Bangweulu craton, indicating a wide plate boundary zone. The seismogenic layer thickness is 42 km, spanning the entire crust beneath the rift basins and their uplifted flanks. Earthquakes in the upper mantle are also detected. Deep earthquakes with steep nodal planes occur along subsurface projections of Tanganyika and Rukwa border faults, indicating that large offset (≥ 5 km) faults penetrate to the base of the crust, and are the current locus of strain. The focal mechanisms, continuous depth distribution, and correlation with mapped structures indicate that steep, deep border faults maintain a half‐graben morphology over at least 12 My of basin evolution. Fault scaling based on our results suggests M > 7 earthquakes along Tanganyika border faults are possible.
0278-7407
Lavayssiere, Aude
4754825b-d4c7-45ec-b715-b46a7c92f042
Drooff, Connor
c6041312-ba45-4cdd-b98b-7c914640af51
Ebinger, Cynthia
9aab3b18-294f-4cda-b64d-375b1cae85bb
Gallacher, Ryan
689f755f-b4a0-4a3b-9959-93c2fae0ac2c
Illsley-Kemp, Finnigan
c24ef4cb-cbf9-4a58-af8d-da9c7eabd84d
Oliva, Sarah J.
3696088e-d5c2-492b-8515-c039a672740b
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Lavayssiere, Aude
4754825b-d4c7-45ec-b715-b46a7c92f042
Drooff, Connor
c6041312-ba45-4cdd-b98b-7c914640af51
Ebinger, Cynthia
9aab3b18-294f-4cda-b64d-375b1cae85bb
Gallacher, Ryan
689f755f-b4a0-4a3b-9959-93c2fae0ac2c
Illsley-Kemp, Finnigan
c24ef4cb-cbf9-4a58-af8d-da9c7eabd84d
Oliva, Sarah J.
3696088e-d5c2-492b-8515-c039a672740b
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65

Lavayssiere, Aude, Drooff, Connor, Ebinger, Cynthia, Gallacher, Ryan, Illsley-Kemp, Finnigan, Oliva, Sarah J. and Keir, Derek (2019) Depth extent and kinematics of faulting in the southern Tanganyika rift, Africa. Tectonics. (doi:10.1029/2018TC005379).

Record type: Article

Abstract

Unusually deep earthquakes occur beneath rift segments with and without surface expressions of magmatism in the East African Rift system (EARS). The Tanganyika rift is part of the Western rift and has no surface evidence of magmatism. The TANG14 array was deployed in the southern Tanganyika rift, where earthquakes of magnitude up to 7.4 have occurred, to probe crust and upper mantle structure and evaluate fault kinematics. 474 earthquakes detected between June 2014 and September 2015 are located using a new regional velocity model. The precise locations, magnitudes and source mechanisms of local and teleseismic earthquakes are used to determine seismogenic layer thickness, delineate active faults, evaluate regional extension direction, and evaluate kinematics of border faults. The active faults span more than 350 km with deep normal faults transecting the thick Bangweulu craton, indicating a wide plate boundary zone. The seismogenic layer thickness is 42 km, spanning the entire crust beneath the rift basins and their uplifted flanks. Earthquakes in the upper mantle are also detected. Deep earthquakes with steep nodal planes occur along subsurface projections of Tanganyika and Rukwa border faults, indicating that large offset (≥ 5 km) faults penetrate to the base of the crust, and are the current locus of strain. The focal mechanisms, continuous depth distribution, and correlation with mapped structures indicate that steep, deep border faults maintain a half‐graben morphology over at least 12 My of basin evolution. Fault scaling based on our results suggests M > 7 earthquakes along Tanganyika border faults are possible.

Text
Lavayssi-re_et_al-2019-Tectonics - Accepted Manuscript
Download (1MB)

More information

Accepted/In Press date: 30 January 2019
e-pub ahead of print date: 3 February 2019
Published date: 7 February 2019

Identifiers

Local EPrints ID: 428264
URI: https://eprints.soton.ac.uk/id/eprint/428264
ISSN: 0278-7407
PURE UUID: 777af5fe-21c0-4163-94b9-edb915c4ac0d
ORCID for Finnigan Illsley-Kemp: ORCID iD orcid.org/0000-0002-7114-033X
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

Catalogue record

Date deposited: 19 Feb 2019 17:30
Last modified: 15 Aug 2019 04:01

Export record

Altmetrics

Contributors

Author: Connor Drooff
Author: Cynthia Ebinger
Author: Ryan Gallacher
Author: Sarah J. Oliva
Author: Derek Keir ORCID iD

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×