207-12 Documenting Quaternary Fault Slip using High Resolution Structure-from-Motion (SfM) Photogrammetry Dataset: Insights from the Albertine Rift, East African Rift System

Session: Honoring the Late Professor Mohamed Abdelsalam: Outstanding Researcher, Generous Colleague, Legendary Mentor, and Ambassador for the Geosciences In Africa

Presenting Author:

Hillary Mwongyera

Authors:

Mwongyera, Hillary¹, Mongovin, Daniel², Taylor, Michael³, Stamps, D. Sarah⁴, Atekwana, Estella⁵, van der Lee, Suzan⁶, Evans, Rob⁷, Katumwehe, Andrew⁸, Barry, Peter⁹, Xue, Liang¹⁰, Kwagalakwe, Asenath¹¹, Kabanda, Albert¹², Njinju, Emmanuel¹³, Oluwasegun, Isaac¹⁴, Kiberu, John¹⁵

Abstract:

The Albertine Rift is a seismically active rift basin of the Western Branch of the East African Rift System (EARS), characterized by moderate-magnitude earthquakes that influence fault slip on rift-bounding normal faults. While the widely available Shuttle Radar Topography Mission (SRTM) provides an invaluable resource for neotectonic studies, the dataset is imprecise for determining accurate offset magnitudes at the meter scale.  We therefore utilize high-resolution topographic datasets generated from Structure from Motion (SfM) photogrammetry to document Quaternary fault slip at the Kibiro field site along the North Toro Bunyoro fault, a prominent rift bounding fault in the Albertine Rift. These drone-acquired images were processed to produce high-resolution (18 cm/pixel) topographic products, including a digital elevation model (DEM), hillshade, slope, and relief maps. These products are useful for quantifying accurate offset magnitudes from fault-truncated alluvial fan geomorphic markers. Vertical offset magnitudes of 6.86 ± 0.12 m and 3.92 ± 0.08 m were obtained for the upper and lower fan surfaces, respectively. The processed topographic products are invaluable for identifying piercing points and obtaining accurate offsets from geomorphic markers in regions where high-resolution data is often sparse or absent. Offset magnitudes will be integrated with 10Be depth-profile age constraints from the displaced fan surfaces to obtain a Quaternary fault slip rate. This study is the first SfM photogrammetry analysis along the EARS, providing key insights into Quaternary fault slip rates along the Albertine Rift and a framework for understanding the dynamics of continental breakup in regions with limited high-resolution geospatial data.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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