Under-Displaced Normal Faults: Strain Accommodation Along an Early-Stage Rift-Bounding Fault in the Southern Malawi Rift

One of the fundamental problems in continental rift segmentation and propagation is how strain accommodated along large rift-bounding faults (border faults) since propagating border control expression zones, syn-rift depo-centers, long-term basin evolution. In Southern Malawi Rift, where previous studies on early-stage rifting only assessed fault structure from surficial topographic expression, we integrate surface subsurface data to investigate segmentation, linkage, growth as proxies for accommodation Bilila-Mtakataka Fault (BMF) System. We used 30 m-resolution relief maps, electrical resistivity tomography (ERT), high-resolution aeromagnetic characterize detailed geometry provide a more robust estimate along-fault displacement distribution. Our results reveal discrepancy between sub-aerial BMF (six segments), scarp height (five segments) reflecting most recent episodes offset, cumulative throw (three composite offset. also observe that although exhibits continuity scarps its length, distribution shows higher at Northern-to-Central segment relay zone (423 m absolute, 364 moving median) compared Central-to-Southern (371 297 median). The ERT profiles across zones suggest shallower basement possible canyon-mouth alluvial fan stratigraphy zone, contrasting deeper “simpler” relay. complex evolution than was assumed studies. A comparison BMF’s maximum displacement-vs-length with those other Rift global normal populations has possibly reached it remains largely under-displaced 580–837 significantly lower equivalent length. may continue accrue significant tectonic extension progresses thus posing major seismic hazard region.