Abstract: A passive loop antenna assembly is configured to detect distant rock fractures. The loop antenna assembly has a loop antenna spun around an enclosure ring. An enclosure is arranged around the enclosure ring and further has an opening portion exposing a portion of the loop antenna. A wave guide assembly is arranged over the loop antenna and has amplifier circuitry that is wired to two leads from the loop antenna. A support structure is joined to the enclosure, the wave guide, and a turntable. A base is joined to the turntable and further has roller guides, roller bearings, and base feet.