Active fault mapping in Karonga-Malawi after the December 19, 2009 Ms 6.2 seismic event

Macheyeki, Athanas S.; Mdala, Hassan; Chapola, L. S.; Manhiça, V.; Chisambi, Joshua; Feitio, P.; Ayele, Atalay; Barongo, Justus; Ferdinand, R.; Ogubazghi, Ghebrebrhan; Goitom, Berhe; Hlatywayo, J.D.; Kianji, G.; Marobhe, Isaac M.; Mulowezi, A.; Mutamina, D. M.; Mwano, J.M.; Shumba, Blessing; Tumwikirize, I.

doi:10.1016/j.jafrearsci.2014.10.010

Cited by 27 publications

(40 citation statements)

References 22 publications

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“…However, a number of intrabasin faults are present as well. The occurrence of a sequence of earthquakes in 2009 with magnitudes up to M w 6 on one or more west-dipping intrabasin faults near Karonga in northern Malawi clearly indicates that some of these faults remain active (Biggs et al, 2010;Fagereng, 2013;Macheyeki et al, 2015; see Fig. 1a for locations).…”

Section: Tectonic Backgroundmentioning

confidence: 99%

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Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift

Shillington

Gaherty

Ebinger

et al. 2016

Seismological Research Letters

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The Study of Extension and maGmatism in Malawi aNd Tanzania (SEGMeNT) project acquired a comprehensive suite of geophysical and geochemical datasets across the northern Malawi (Nyasa) rift in the East Africa rift system. Onshore/offshore active and passive seismic data, long-period and wideband magnetotelluric data, continuous Global Positioning System data, and geochemical samples were acquired between 2012 and 2016. This combination of data is intended to elucidate the sedimentary, crustal, and upper-mantle architecture of the rift, patterns of active deformation, and the origin and age of rift-related magmatism. A unique component of our program was the acquisition of seismic data in Lake Malawi, including seismic reflection, onshore/offshore wide-angle seismic reflection/refraction, and broadband seismic data from lake-bottom seismometers, a towed streamer, and a large towed air-gun source. SCIENCE MOTIVATION AND EXPERIMENT SUMMARYThe primary scientific goal of the Study of Extension and maGmatism in Malawi aNd Tanzania (SEGMeNT) project is to examine the emergence and early evolution of two fundamental features of all divergent plate boundaries: magmatism and segmentation. Magmatism accommodates a significant percentage of plate separation at most midocean ridges and late-stage continental rifts. Likewise, transform faults demarcate discrete spreading segments in midocean ridges, which are broadly characterized by more robust magmatism at their centers than at their edges (Macdonald et al., 1988;Lin et al., 1990). Well-developed magmatic and tectonic segmentation is also observed in late-stage continental rifts and new ocean basins (Taylor et al., 1995;Ebinger and Casey, 2001;Keir et al., 2009), but little is known about the controls on the initiation and development of magmatism and segmentation in immature rifts. Our project is focused on addressing the following questions:• When, where, and why does magmatism initiate in rifts, and what is its role in accommodating extension? • What controls the development of tectonic segmentation in early-stage rifts? How is it manifested in 4D patterns of magmatism and deformation?To address the questions above, we acquired an integrated geophysical and geochemical dataset across the northern Malawi (Nyasa) rift in the southern part of the East Africa Rift system (EARS). Our team included universities and geological surveys in the United States, Malawi, and Tanzania. The following datasets were acquired as a part of the SEGMeNT project: onshore/offshore active and passive seismic data, long-period and wideband magnetotelluric (MT) data, continuous Global Positioning System (GPS) data, and geochemical samples. This is the first integrated geophysical and geochemical dataset acquired across and within any of the great African rift lakes that can constrain rift architecture and processes at a range of scales. TECTONIC BACKGROUNDThe northern Malawi (Nyasa) rift in the Western Branch of the EARS is an excellent locality to examine the early stages of rifting in str...

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Section: Tectonic Backgroundmentioning

confidence: 99%

“…2013; Macheyeki et al, 2015), active intrabasin faults also pose a hazard to people living near the lakeshore; such faults could potentially be associated with near-field tsunamis.…”

Section: Tectonic Backgroundmentioning

confidence: 99%

Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift

Shillington

Gaherty

Ebinger

et al. 2016

Seismological Research Letters

View full text Add to dashboard Cite

show abstract

“…Data on earthquakes in Karonga has been collected since 1904 (Lunduka et al, 2010;Macheyeki et al, 2014). Figure 4 shows a number of epicentres since 1904 (Macheyeki et al, 2014).…”

Section: Seismicity Of Malawi and Karonga District From 1901 To 2014mentioning

confidence: 99%

“…Karonga is located at the northern tip of the Malawi Rift System (Figure 1). Seismic data indicate Karonga and northern Malawi are the most seismically active areas in The occurrence of earth tremors are not a new phenomenon in Karonga town (Macheyeki et al, 2014). The tectonic activities are typical of Karonga town since the town lies on a fault line parallel to the Livingstone fault which forms Lake Malawi (Geological Survey of Malawi, 1966;Biggs et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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The earthquake/seismic risk, vulnerability and capacity profile for Karonga town

Kushe¹,

Manda²,

Mdala³

et al. 2017

Afr. J. Environ. Sci. Technol.

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The study was carried out to understand the risks posed by earthquakes in Karonga based on roles and perception of stakeholders. Information was collected from several stakeholders who were found responding to earthquakes impacts in Karonga Town. The study found that several stakeholders, governmental and non-governmental department and organisation operate in Karonga District to respond to hazards and disasters that occur in the district however most of these stakeholders concentrate their activities in rural areas than the town despite having the town experiencing greater impacts from earthquake hazards. The study also found that people of Karonga are aware of earthquakes and how they can avoid their impacts however their economic status fail them from developing infrastructure that can help them to avoid or recover quickly from the impacts of earthquake disasters. It is therefore concluded that the people of Karonga town are vulnerable to earthquake hazards due to limited capacity to develop appropriate infrastructure that can survive seismic hazards.

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Active Deformation of Malawi Rift's North Basin Hinge Zone Modulated by Reactivation of Preexisting Precambrian Shear Zone Fabric

et al. 2018

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We integrated temporal aeromagnetic data and recent earthquake data to address the long‐standing question on the role of preexisting Precambrian structures in modulating strain accommodation and subsequent ruptures leading to seismic events within the East African Rift System. We used aeromagnetic data to elucidate the relationship between the locations of the 2009 Mw 6.0 Karonga, Malawi, earthquake surface ruptures and buried basement faults along the hinge zone of the half‐graben comprising the North Basin of the Malawi Rift. Through the application of derivative filters and depth‐to‐magnetic‐source modeling, we identified and constrained the trend of the Precambrian metamorphic fabrics and correlated them to the three‐dimensional structure of buried basement faults. Our results reveal an unprecedented detail of the basement fabric dominated by high‐frequency WNW to NW trending magnetic lineaments associated with the Precambrian Mughese Shear Zone fabric. The high‐frequency magnetic lineaments are superimposed by lower frequency NNW trending magnetic lineaments associated with possible Cenozoic faults. Surface ruptures associated with the 2009 Mw 6.0 Karonga earthquake swarm aligned with one of the NNW‐trending magnetic lineaments defining a normal fault that is characterized by right‐stepping segments along its northern half and coalesced segments on its southern half. Fault geometries, regional kinematics, and spatial distribution of seismicity suggest that seismogenic faults reactivated the basement fabric found along the half‐graben hinge zone. We suggest that focusing of strain accommodation and seismicity along the half‐graben hinge zone is facilitated and modulated by the presence of the basement fabric.

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Active fault mapping in Karonga-Malawi after the December 19, 2009 Ms 6.2 seismic event

Cited by 27 publications

References 22 publications

Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift

Acquisition of a Unique Onshore/Offshore Geophysical and Geochemical Dataset in the Northern Malawi (Nyasa) Rift

The earthquake/seismic risk, vulnerability and capacity profile for Karonga town

Active Deformation of Malawi Rift's North Basin Hinge Zone Modulated by Reactivation of Preexisting Precambrian Shear Zone Fabric

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