Phase sensitive optical time domain reflectometers (φ-OTDRs) have been widely employed in pipeline safety early warning systems, optical cable break-point searches, mechanical pipeline pig (PIG) positing and tracking, and other fields. The sensing optical cables of φ-OTDRs are mostly buried underground so that the soil characteristics, transmission distances, and optical cable structures all have considerable effects on the signal characteristics. This study considered the propagation characteristics of vibration signals in soils and explored the effects of non-event factors such as optical cable structures, soil moisture, and transmission distances on the signal characteristics of systems. In addition, in terms of energy change trends in characteristic frequency bands, the difference between real shock vibration and non-event signal fluctuations was investigated. A proposed method to judge external shock vibration is derived from the results.