Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana: The 3 April 2017 Central Botswana Earthquake Linked to the East African Rift System

Islam Fadel; Hanneke Paulssen; Mark van der Meijde; Motsamai Kwadiba; Onkgopotse Ntibinyane; Andrew Nyblade; Raymond Durrheim

doi:10.1029/2019GL085598

Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana: The 3 April 2017 Central Botswana Earthquake Linked to the East African Rift System

Islam Fadel^*, Hanneke Paulssen, Mark van der Meijde, Motsamai Kwadiba, Onkgopotse Ntibinyane, Andrew Nyblade, Raymond Durrheim

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Rayleigh wave group and phase velocity measurements obtained from ambient noise and earthquake data at 51 broadband stations were used to construct the first 3-D crustal and upper mantle shear wave velocity model of Botswana. The model shows low crustal velocities associated with the Passarge and Nosop sedimentary basins, whereas the Kaapvaal, Zimbabwe, Maltahohe, and Congo Cratons are recognized by high mantle velocities. The lowest upper mantle shear wave velocity, beneath northeastern Botswana, is associated with the southwestern branch of the East African Rift System. This low-velocity mantle anomaly appears to be linked to the crust of the Okavango Rift Zone and the location of the 3 April 2017 M_w 6.5 earthquake in central Botswana. We suggest that fluids or melt at the base of the crust from the southward continuation of the East African Rift Zone triggered the intraplate earthquake in an extensional tectonic setting.

Original language	English
Article number	e2019GL085598
Number of pages	12
Journal	Geophysical Research Letters
Volume	47
Issue number	4
DOIs	https://doi.org/10.1029/2019GL085598
Publication status	Published - 28 Feb 2020

Funding

This work was funded by the Netherlands Organization for Scientific Research (NWO), Grant ALW-GO-AO/11-30. We thank Arie van Wettum (Utrecht University) and the deployment team of the Botswana Geoscience Institute for their efforts to install and maintain the NARS-Botswana network. Data used in this study can be accessed from the IRIS data management center (http://ds.iris.edu/ds/).

Keywords

ambient noise
continental rift
craton
earthquakes
seismology
surface wave tomography

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title = "Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana: The 3 April 2017 Central Botswana Earthquake Linked to the East African Rift System",

abstract = "Rayleigh wave group and phase velocity measurements obtained from ambient noise and earthquake data at 51 broadband stations were used to construct the first 3-D crustal and upper mantle shear wave velocity model of Botswana. The model shows low crustal velocities associated with the Passarge and Nosop sedimentary basins, whereas the Kaapvaal, Zimbabwe, Maltahohe, and Congo Cratons are recognized by high mantle velocities. The lowest upper mantle shear wave velocity, beneath northeastern Botswana, is associated with the southwestern branch of the East African Rift System. This low-velocity mantle anomaly appears to be linked to the crust of the Okavango Rift Zone and the location of the 3 April 2017 Mw 6.5 earthquake in central Botswana. We suggest that fluids or melt at the base of the crust from the southward continuation of the East African Rift Zone triggered the intraplate earthquake in an extensional tectonic setting.",

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author = "Islam Fadel and Hanneke Paulssen and Mark van der Meijde and Motsamai Kwadiba and Onkgopotse Ntibinyane and Andrew Nyblade and Raymond Durrheim",

year = "2020",

month = feb,

day = "28",

doi = "10.1029/2019GL085598",

language = "English",

volume = "47",

journal = "Geophysical Research Letters",

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Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana: The 3 April 2017 Central Botswana Earthquake Linked to the East African Rift System. / Fadel, Islam; Paulssen, Hanneke; van der Meijde, Mark et al.
In: Geophysical Research Letters, Vol. 47, No. 4, e2019GL085598, 28.02.2020.

Research output: Contribution to journal › Article › Academic › peer-review

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T1 - Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana

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AU - Fadel, Islam

AU - Paulssen, Hanneke

AU - van der Meijde, Mark

AU - Kwadiba, Motsamai

AU - Ntibinyane, Onkgopotse

AU - Nyblade, Andrew

AU - Durrheim, Raymond

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Crustal and Upper Mantle Shear Wave Velocity Structure of Botswana: The 3 April 2017 Central Botswana Earthquake Linked to the East African Rift System

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