Rifting in the Kalahari?

Reeves, C.V.

doi:10.1038/237095a0

Cited by 107 publications

(59 citation statements)

References 2 publications

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“…Our velocities correspond still better with the MIDAS automatic computation using GIPSY OASIS II software (Blewitt et al, 2016). These results are also consistent with the predictions of Reeves (1972b) and McCarthy (2013) for a very low deformation rate in the structure.…”

Section: Accepted M Manuscriptsupporting

confidence: 82%

Is the Okavango Delta the terminus of the East African Rift System? Towards a new geodynamic model: Geodetic study and geophysical review

et al. 2017

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The Okavango Graben (OG) has been considered as the terminus of the southwestern branch of the East African Rift System (EARS) since the 1970's based on fault morphology and early seismic and geophysical data. Thus it is assumed to be an incipient rifting zone, analogous to the early stage of mature rifts in the EARS. Recent geodetic data and geophysical studies in the area bring new insights on the local crust and lithosphere, mantle activity and fault activity. In this study, we computed the velocities for three permanent GPS stations surrounding the graben and undertook a review of the new geophysical data available for the area. The northern and southern blocks of the graben show exclusively a low strike-slip displacement rate of about 1 mm/yr, revealing the transtensional nature of this basin. The seismic record of central and southern Africa is revealed to be instrumentally biased for the events recorded before 2004 and the OG may not represent the most seismically active area in Botswana anymore.Moreover, no significant lithosphere and crustal thinning is found in the tectonic structure as well as no strong negative Bouguer anomaly and surface heat flux. Thus the OG does not match the classical model for a rifting zone.We propose a new geodynamic model for the deformation observed west of the EARS based on accommodation of far-field deformation due to the differential extension rates of the EARS and the displacement of the Kalahari craton relative to the Nubian plate.Keywords: Intraplate tectonics, Okavango, Geodesy, East African Rift System. Highlights : -Time series for three GPS stations astride the Okavango graben have been processed.-The Okavango graben showed main strike-slip displacement over the five past years.-There is no significant evidence for rifting in the area.-Deformation in the region can be explained by far-field deformation accommodation.

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Section: Accepted M Manuscriptsupporting

confidence: 82%

Is the Okavango Delta the terminus of the East African Rift System? Towards a new geodynamic model: Geodetic study and geophysical review

et al. 2017

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“…(Figure 1b,c) [6]. In this area, a major seismic swarm was observed between 1951 and 1953, culminating with the M L 6.1 and 6.7 events on 11 September 1952 and 11 October 1952, respectively [6].…”

Section: Introductionmentioning

confidence: 99%

“…1953, culminating with the ML 6.1 and 6.7 events on 11 September 1952 and 11 October 1952, respectively [6]. To the south, the epicentral area of the Mw 6.5 event has not experienced strong earthquakes in the past.…”

Section: Introductionmentioning

confidence: 99%

Did Anthropogenic Activities Trigger the 3 April 2017 Mw 6.5 Botswana Earthquake?

et al. 2017

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Abstract:On 3 April 2017, a M w 6.5 earthquake occurred in Botswana, representing the secondstrongest earthquake registered since 1949. Such an intraplate event occurred in a low seismic hazard area and was suspected to be an artificial earthquake induced by nearby anthropogenic activities (gas extraction). The possible relation between anthropogenic activities and the earthquake occurrence has been qualitatively investigated. We estimated the geometric and kinematic characteristics of the causative fault from the modeling of Sentinel-1 InSAR interferograms. Our best-fit solution for the main shock is represented by a normal fault located at a depth greater than 20 km, dipping 65 • northeast, with a right-lateral component, and a mean slip of 2.7 m. The retrieved fault geometry and mechanism are incompatible with the hypothetical stress perturbation caused by the anthropogenic activities performed in the area. Therefore, the 3 April 2017 Botswana earthquake can be classified as a natural intraplate earthquake.

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“…As for the Phuti and Nare faults vertical displacement along them is very small (Fig 8). This therefore indicates that the Kunyere fault is the main westerly dipping bounding fault to the east of the rift system, consistent with its higher seismic activity (Reeves, 1972). The Kunyere and Thamalakane faults displace the dike swarm along its entire width, whereas the Phuti and Nare faults only displace the northern portion of the swarm (Fig.3 and 6).…”

Section: Faulting In the Areamentioning

confidence: 52%

“…2). This approximately 70-km-wide dike swarm extends from Zimbabwe in the east, through the study area in Botswana, into northeastern part of Namibia to the northwest (Reeves, 1972). The dykes are superimposed on northeasterly trending folds and faults of the Neoproterozoic Ghanzi-Chobe belt and are cut by younger faults (Fig.…”

Section: Resultsmentioning

confidence: 99%

Geomorphic Landforms and Tectonism Along the Eastern Margin of the Okavango Rift Zone, North Western Botswana as Deduced from Geophysical Data in the Area

Shemang¹,

Molwalefhe²

2011

New Frontiers in Tectonic Research - General Problems, Sedimentary Basins and Island Arcs

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Rifting in the Kalahari?

Cited by 107 publications

References 2 publications

Is the Okavango Delta the terminus of the East African Rift System? Towards a new geodynamic model: Geodetic study and geophysical review

Is the Okavango Delta the terminus of the East African Rift System? Towards a new geodynamic model: Geodetic study and geophysical review

Did Anthropogenic Activities Trigger the 3 April 2017 Mw 6.5 Botswana Earthquake?

Geomorphic Landforms and Tectonism Along the Eastern Margin of the Okavango Rift Zone, North Western Botswana as Deduced from Geophysical Data in the Area

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