Active Fault Mapping in the Northern Basin of the Malawi Rift and Implications for Seismic Hazard

Starts:  25 June 2026   16: 00

Ends:    25 June 2026   17:00

Central Africa Time (CAT)

Speaker:

Patrick R.N. Chindandali

Geological Survey of Malawi - Geohazards Monitoring Section;
Northern Arizona University, School of Earth and Sustainability

Abstract:

In early-stage rift systems such as the Malawi Rift in the East African Rift System, the geometries and slip histories of intrarift faults remain poorly resolved, leaving questions about strain partitioning and earthquake hazard. Here, we focus on the North Basin of the Malawi Rift, a NNW-SSE oriented basin bounded by the Livingstone Border Fault. The basin trend is oblique to the regional W-E extension direction, making it a useful setting for examining how obliquity influences intrarift fault development and slip behavior.

Recent high-resolution multibeam bathymetric and CHIRP sub-bottom data from the North Basin reveal a network of active intrarift faults. The Timba Fault, the largest intrarift structure, is at least 44 km long and shows along-strike changes in orientation, from a NNW-SSE trend in the north to WNW-ESE trend in the south. Other faults subparallel to the Timba Fault have smaller scarp heights. South of the Timba Fault, shorter N-S to NNE-SSW striking faults are oblique to both the border fault and the Timba Fault, providing evidence for strain partitioning associated with oblique rifting. A total of nine seismic horizons were interpreted and correlated with age-constrained sedimentary units from drill core Site MAL-2A. Cumulative scarp height increases with horizon depth and age, indicating repeated fault activity through the time interval represented by these horizons. Moment magnitude estimates from fault scaling relationships suggest that some mapped faults in the basin may be capable of generating Mw 4.8 to 7.0 earthquakes.

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