Controls on Early-Rift Geometry: New Perspectives From the Bilila-Mtakataka Fault, Malawi

M. Hodge*, Fagereng, J. Biggs, H. Mdala

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

15 Citations (Scopus)
250 Downloads (Pure)


We use the ∼110-km long Bilila-Mtakataka fault in the amagmatic southern East African Rift, Malawi, to investigate the controls on early-rift geometry at the scale of a major border fault. Morphological variations along the 14 ± 8-m high scarp define six 10- to 40-km long segments, which are either foliation parallel or oblique to both foliation and the current regional extension direction. As the scarp is neither consistently parallel to foliation nor well oriented for the current regional extension direction, we suggest that the segmented surface expression is related to the local reactivation of well-oriented weak shallow fabrics above a broadly continuous structure at depth. Using a geometrical model, the geometry of the best fitting subsurface structure is consistent with the local strain field from recent seismicity. In conclusion, within this early-rift, preexisting weaknesses only locally control border fault geometry at subsurface.

Original languageEnglish
Pages (from-to)3896-3905
Number of pages10
JournalGeophysical Research Letters
Issue number9
Early online date20 Apr 2018
Publication statusPublished - 16 May 2018


  • EARS
  • fault scarp
  • foliation
  • geometry
  • normal fault
  • rift

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