Seismic hazard in central southern Africa

Hlatywayo, Dumisani John

doi:10.1111/j.1365-246x.1997.tb01868.x

Cited by 9 publications

(4 citation statements)

References 23 publications

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“…An attempt to determine the actual fault plane is done here by comparing the obtained solution with notable major observed fault lineaments. Hlatywayo (1995;1997) noted that the main lineaments in the Hwange, Zambezi Basin to the north of our study area, trend in the north-easterly direction further north into the Luangwa river valley in eastern Zambia. Furthermore, Vail (1967) showed the trend of lineaments from Botswana running northeasterly through Hwange and Kariba gorge into Luangwa valley.…”

Section: Discussionmentioning

confidence: 95%

Focal Mechanism Solution of the 15th March 2008, Nyamandlovu Earthquake

Shumba¹,

Hlatywayo

Midzi

2009

South African Journal of Geology

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The focal mechanism solution of the 15th March 2008 earthquake (mb = 4.3) that occurred in the Nyamandlovu area, northwest of Bulawayo City, Zimbabwe, has been determined from P-wave first motion polarities. Results show normal oblique left lateral faulting. The earthquake mechanism bears a signature that is almost identical to those of events recorded in the Zambezi Branch of the East African Rift Zone. Synthetic seismograms compared with observed data from regional stations were employed for depth determination. This event had a shallow depth of 5 km. Earthquakes in the area tend to occur either after a significant drought or a wet season of considerable length. The area is underlain by thick Karoo sandstones that form an aquifer of high potential water storage. These events are therefore most probably induced by pore -pressure differentials in the underlying rock.

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Section: Discussionmentioning

confidence: 95%

Focal Mechanism Solution of the 15th March 2008, Nyamandlovu Earthquake

Shumba¹,

Hlatywayo

Midzi

2009

South African Journal of Geology

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“…Zimbabwe's seismic activity is generally considered to be moderate, with a few notable occurrences around the country's northern region, which includes the Zambezi area, Nyamandlovu area, and Zimbabwe-Mozambique border situated at the southernmost point of the East African Rift System [19][20][21][22]. Three seismic zones make up Zimbabwe's territory: the eastern region, the central region, and the Zambezi basin.…”

Section: Seismicity Of the Study Areamentioning

confidence: 99%

“…The southernmost point of the East African Rift System is where Zimbabwe is located [19]. Three seismic zones make up Zimbabwe's seismic activity: the eastern region, the central region, and the Zambezi basin region.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the Probability of Earthquakes Return Period in Zimbabwe Using Gumbel’s Extreme Value Theory Method

Atsu, J. U.,

Abong, A. A.

2023

ARJOM

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Using Gumbel's extreme value theory method, this study looked into the probability of the largest earthquakes for different return periods in Zimbabwe. The Advanced National Seismic System (ANSS), the Northern California Earthquake Data Centre website, and UC Berkeley in the United States provided the data used for this study. The natural earthquakes with Mb ≥ 4.0 that occurred in the study area between January 1, 1901 and December 31, 2001 (a period of 100 years) with a focal depth ranging from 0 to 700 km made up the selected data. The study area is between 150S - 220S and 250E -340E in coordinates. A total of 81 events were used in the investigation. According to the results, there is a 100% chance that earthquakes with a magnitude between 4.5 and 5.5 will occur during the time interval of approximately 1 to 14 years and a 9.5% chance that within the next 100 years, there will be an earthquake with a magnitude of Mb = 6.0 or higher. For magnitudes Mb = 6.0 and above, the return period is relatively long - roughly 50 – 701 years. This suggests that there is little chance that Zimbabwe will experience earthquakes larger than magnitude 6.0. Despite being low, it is impossible to forecast with certainty because earthquake forecasting and prediction is still a complex topic.

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“…In previous regional and/or continental studies (e.g. Ayele et al, 2007;Mavonga and Durrheim, 2009;Midzi et al, 1999;Hlatywayo, 1997) it became clear that very limited information on the long-term earthquake activity and recurrence of seismic ruptures was available for effectively assessing the seismic hazard. Hence, previous studies focused on probabilistic seismic hazard assessments that considered large seismic source areas.…”

Section: Implications For the Seismic Hazard Assessmentmentioning

confidence: 99%

The Seismotectonic Map of Africa

Meghraoui¹

2016

Episodes

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We present the Seismotectonic Map of Africa based on a geological, geophysical and geodetic database including instrumental seismicity and re-appraisal of large historical events, and harmonization and homogenization of earthquake parameters in the catalogues. Although establishing the seismotectonic framework of the African continent is a difficult task, several previous and ongoing projects provide a wealth of data and outstanding results. The database of large and moderate earthquakes in different geological domains includes the coseismic and Quaternary faulting that reveals the complex nature of the active tectonics in Africa. The map benefits from previous works on local and regional seismotectonic maps that needed to be integrated with the lithospheric and upper mantle structures, seismic anisotropy tomography and gravity anomaly, into a continental framework. The synthesis of earthquake and volcanic studies obtained from the analysis of late Quaternary faulting and geodetic data will serve as a basis for hazard calculations and the reduction of seismic risks. The map will be useful for the seismic hazard assessment and earthquake risk mitigation for significant infrastructures and their socioeconomic implications in Africa. The constant population increase and infrastructure growth in the continent that exacerbate earthquake risk justify the necessity of continuously updating this map. The database and related map are prepared in the framework of the IGC Project-601 "Seismotectonics and Seismic Hazards in Africa" of UNESCO-IUGS, funded by the Swedish International Development Agency and UNESCO-Nairobi for a period of 4 years (2011-2014, now extended to 2016).

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Seismic hazard in central southern Africa

Cited by 9 publications

References 23 publications

Focal Mechanism Solution of the 15th March 2008, Nyamandlovu Earthquake

Focal Mechanism Solution of the 15th March 2008, Nyamandlovu Earthquake

Estimation of the Probability of Earthquakes Return Period in Zimbabwe Using Gumbel’s Extreme Value Theory Method

The Seismotectonic Map of Africa

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