Active Fault Mapping in Karonga-Malawi after the December 19, 2009 Ms 6.2 Seismic Event
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Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
The East African Rift System (EARS) has natural hazards – earthquakes, volcanic eruptions, and landslides
along the faulted margins, and in response to ground shaking. Strong damaging earthquakes have been
occurring in the region along the EARS throughout historical time, example being the 7.4 (Ms) of December
1910. The most recent damaging earthquake is the Karonga earthquake in Malawi, which occurred on
19th December, 2009 with a magnitude of 6.2 (Ms). The earthquake claimed four lives and destroyed over
5000 houses. In its effort to improve seismic hazard assessment in the region, Eastern and Southern Africa
Seismological Working Group (ESARSWG) under the sponsorship of the International Program on Physical
Sciences (IPPS) carried out a study on active fault mapping in the region.
The fieldwork employed geological and geophysical techniques. The geophysical techniques employed
are ground magnetic, seismic refraction and resistivity surveys but are reported elsewhere. This article
gives findings from geological techniques. The geological techniques aimed primarily at mapping of
active faults in the area in order to delineate presence or absence of fault segments. Results show that
the Karonga fault (the Karonga fault here referred to as the fault that ruptured to the surface following
the 6th–19th December 2009 earthquake events in the Karonga area) is about 9 km long and dominated
by dip slip faulting with dextral and insignificant sinistral components and it is made up of 3–4 segments
of length 2–3 km. The segments are characterized by both left and right steps.
Although field mapping show only 9 km of surface rupture, maximum vertical offset of about 43 cm
imply that the surface rupture was in little excess of 14 km that corresponds with Mw = 6.4. We recommend
the use or integration of multidisciplinary techniques in order to better understand the fault
history, mechanism and other behavior of the fault/s for better urban planning in the area.
Description
Keywords
December 2009 seismic event, Active fault mapping, Fault segment, Karonga, Malawi
Citation
Macheyeki, A.S., Mdala, H., Chapola, L.S., Manhiça, V.J., Chisambi, J., Feitio, P., Ayele, A., Barongo, J., Ferdinand, R.W., Ogubazghi, G. and Goitom, B., 2015. Active fault mapping in Karonga-Malawi after the December 19, 2009 Ms 6.2 seismic event. Journal of African Earth Sciences, 102, pp.233-246.