Premium
Breaking up the hanging wall of a rift‐border fault: The 2009 Karonga earthquakes, Malawi
Author(s) -
Biggs J.,
Nissen E.,
Craig T.,
Jackson J.,
Robinson D. P.
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl043179
Subject(s) - geology , rift , seismology , fault (geology) , rift zone , focal mechanism , tectonics
The southern East African Rift has an unusually large seismogenic thickness (35–40 km), which is responsible for wide tilted basins and extremely long faults with the potential for M7‐8 normal‐faulting earthquakes. From 6–19 December 2009, a shallow earthquake sequence (four of M w > 5.5) hit the Karonga region of northern Lake Malawi. The location is 50 km west of the rift‐bounding Livingstone Fault, within the hanging‐wall. We used seismology and InSAR to obtain source parameters and combined this with information on rift structure from geomorphology and seismic profiles. The deformation is consistent with rupture of a shallow, west‐dipping fault, with no evidence for the involvement of magmatic fluids. Although the Livingstone Fault dominates local geomorphology, the Karonga earthquakes demonstrate that the hanging‐wall block is actively breaking up, reflecting temporal and spatial migration of activity or the release of stresses within it.