23 Upper Crustal Deformation across Continental Interiors from the Mesozoic to the Present (Posters)

Tuesday, 14 March 2017
9:00 AM - 5:30 PM
Grand Ballroom CDE

THE 2009 KARONGA, MALAWI EARTHQUAKE ASSOCIATED WITH PARTIAL RUPTURE OF A BLIND CENOZOIC FAULT: EVIDENCE FROM AEROMAGNETIC AND ELECTRICAL RESISTIVITY DATA

Paper number: 23-6
Program: Theme Sessions
Time: 9:00 AM – 5:30 PM

Authors

Abstract

The 2009 Karonga, Malawi earthquake caused a 14-18 km long surface rupture along a single W-dipping fault on the hinge zone of the E-dipping half graben that form the North Basin of the Malawi Rift. This part of the rift is underlain by the NW-trending Precambrian Mughese Shear Zone (MSZ). We used aeromagnetic and electrical resistivity data to investigate the structure of the ruptured fault, and to elucidate the relationship between surface rupture locations and pre-existing basement structures. Although several magnetic lineaments are visible in the basement, mapped surface ruptures align with a single 37 km-long magnetic anomaly oriented 148°-162°/40°SW, a segment of which coincides with geoelectrical disturbance caused by near-surface soil liquefaction. Fault geometries, regional kinematics and spatial distribution of seismicity suggest that extension in the Karonga area is accommodated by active break-up of the hinge zone of Malawi Rift’s North Basin through transtension and reactivation of faults that originally exploited a segment of the MSZ.

Geological Society of America Abstracts with Programs. Vol. 49, No. 1

doi: 10.1130/abs/2017SC-288899

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