Spectral Analysis of Dynamite Shots of Different Charge Sizes at Varying Shot-Depths in Mid-West Niger Delta, Nigeria

Spectral analysis of dynamite shots in study area of Niger Delta showed strong signal strength with a frequency range up to 0 - 67Hz at detonation, except for defective shot depths or shallow patterns sources. At stipulated shot depths, recorded frequencies were in the range of 5Hz to 100 Hertz. Reflection events on the monitor record were fair-to-good in strength and amplitude. The Signal strength was strong for those shots acquired at the stipulated charge depth of 4m. Thus, optimal signal strength, associated with optimum frequency content can be obtainable at specification depth. Experimental shots with quality controlled drilling, loading and tamping at 4 metres depth for the 2kg explosives charge size had good energy returns with optimal signal strength ranging from 0 to 67Hz. It was however strongest when the charge size was increased (or duplicated) from 2kg to 4kg. The 4kg explosive charge size had very good energy return but was not cost-effective in the production setting.