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<p>Two-dimensional (2D) radial electrical resistivity imaging was applied around the Ground Zero (GZ) of the 18:45 GMT, 17 January 2024 explosion in Bodija, Ibadan, southwestern Nigeria, as an on-site inspection (OSI) geophysical approach to delineate subsurface explosion-induced disturbance patterns and to estimate their lateral and depth extents. The explosion, reportedly linked to improper handling and storage of mining explosives, caused loss of lives, extensive structural damage, and visible ground disruption beyond a 500&#xa0;m radius. Geophysical data were acquired along twelve radial profiles spaced at 30° intervals using a Wenner electrode configuration with a minimum electrode spacing of 5&#xa0;m and progressive expansion to five levels. Apparent resistivity data were filtered, inverted, and integrated to generate individual 2D resistivity sections, combined radial resistivity models, iso-depth resistivity maps, and a three-dimensional subsurface model.</p><p>The results reveal pronounced near-surface low resistivity zones (&lt; 20 Ωm) radiating from the GZ, interpreted as explosion-induced disturbed ground comprising fractures, cracks, and zones of reduced mechanical competence. The disturbance exhibits a preferential NW–SE (east–west dominant) spreading pattern and decreases in intensity and continuity with depth, with the most extensive effects confined to the upper ~ 10&#xa0;m and isolated vertical features extending to depths of ~ 16&#xa0;m. The orientation of the detected disturbance differs from the regional NE–SW Pan-African structural trend, suggesting dominant control by blast dynamics rather than inherited tectonic fabric.</p><p>Interpretation is subject to limitations inherent in electrical resistivity imaging, including non-uniqueness of resistivity anomalies, the absence of pre-explosion baseline geophysical data, and restricted access to the immediate explosion epicenter due to backfilling of the crater and safety constraints. Consequently, while the results robustly define the spatial pattern and depth attenuation of subsurface disturbance, some deeper anomalies may represent a combination of explosion-induced and pre-existing structures. Notwithstanding these limitations, the study demonstrates that radial electrical resistivity imaging is a reliable and effective OSI tool for mapping subsurface explosion impacts and provides valuable information for post-disaster remediation, engineering risk assessment, and future land-use planning in basement complex terrains.</p>

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2D radial electrical resistivity profiling technique for delineating near-surface disturbance pattern associated with the 18:45 GMT 17 January 2024 Ibadan, SW Nigeria explosion

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  • 发表日期：

    2026年7月6日

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  • Olawale Olakunle Osinowo,
  • Peters Shammah Chidoka,
  • Ayodeji Hansen - Ayoola

摘要

Two-dimensional (2D) radial electrical resistivity imaging was applied around the Ground Zero (GZ) of the 18:45 GMT, 17 January 2024 explosion in Bodija, Ibadan, southwestern Nigeria, as an on-site inspection (OSI) geophysical approach to delineate subsurface explosion-induced disturbance patterns and to estimate their lateral and depth extents. The explosion, reportedly linked to improper handling and storage of mining explosives, caused loss of lives, extensive structural damage, and visible ground disruption beyond a 500 m radius. Geophysical data were acquired along twelve radial profiles spaced at 30° intervals using a Wenner electrode configuration with a minimum electrode spacing of 5 m and progressive expansion to five levels. Apparent resistivity data were filtered, inverted, and integrated to generate individual 2D resistivity sections, combined radial resistivity models, iso-depth resistivity maps, and a three-dimensional subsurface model.

The results reveal pronounced near-surface low resistivity zones (< 20 Ωm) radiating from the GZ, interpreted as explosion-induced disturbed ground comprising fractures, cracks, and zones of reduced mechanical competence. The disturbance exhibits a preferential NW–SE (east–west dominant) spreading pattern and decreases in intensity and continuity with depth, with the most extensive effects confined to the upper ~ 10 m and isolated vertical features extending to depths of ~ 16 m. The orientation of the detected disturbance differs from the regional NE–SW Pan-African structural trend, suggesting dominant control by blast dynamics rather than inherited tectonic fabric.

Interpretation is subject to limitations inherent in electrical resistivity imaging, including non-uniqueness of resistivity anomalies, the absence of pre-explosion baseline geophysical data, and restricted access to the immediate explosion epicenter due to backfilling of the crater and safety constraints. Consequently, while the results robustly define the spatial pattern and depth attenuation of subsurface disturbance, some deeper anomalies may represent a combination of explosion-induced and pre-existing structures. Notwithstanding these limitations, the study demonstrates that radial electrical resistivity imaging is a reliable and effective OSI tool for mapping subsurface explosion impacts and provides valuable information for post-disaster remediation, engineering risk assessment, and future land-use planning in basement complex terrains.