Seismic Source sourceType extSourceType refinedSourceType refinedExtSourceType POSC 1.0 dynamite A chemical explosive used to generate seismic waves. Vibroseis A vibratory instrument which is used as an energy source to generate a controlled wave train. air gun A seismic source which injects a bubble of highly compressed air into the water. water gun A seismic source which propels a slug of water into the water mass, producing an implisive effect. weight drop A heavy weight dropped on the ground to generate in impulsive seismic source.