Abstract
Geophysical and geological studies of an Ethiopian maar, Haro Maja, demonstrate that its eruptive history is more complex than surface geology alone suggests. The crater is 750 m by 1000 m in diameter and varies in depth from 70 m to 110 m. A strong magnetic anomaly is caused by a central basaltic mound, but a broader crater-wide anomaly is best modelled by a 50 m thick frozen lava lake, 30 m below the crater floor. The central mound was not erupted directly onto the lava lake, but was extruded onto top of the sedimentary infill after a quiescent depositional interval. Electrical resistivity measurements further indicate that other basaltic intrusions failed to reach the surface during that eruptive period.
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Work done while the authors were at Addis Ababa University, Ethiopia.
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Emilia, D.A., Last, B.J., Wood, C.A. et al. Geophysics and geology of an explosion crater in the Ethiopian rift valley. Bull Volcanol 40, 133–140 (1977). https://doi.org/10.1007/BF02596995
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DOI: https://doi.org/10.1007/BF02596995