The survey using passive seismic, the detection of natural low frequency earth movements, usually with the purpose of discerning geological structure and locate underground oil, gas, or other resources, is very different from the conventional survey, which consists of numerous measurements that are spatially very close together and relatively short (often lasting in the order of minutes).
Passive seismic is the detection of natural low frequency earth movements, usually with the purpose of discerning geological structure and locate underground oil, gas, or other resources. The survey using this method is very different from the conventional survey that is usually based on reflection seismology. The conventional survey consists of numerous measurements that are spatially very close together and relatively short (often lasting in the order of minutes). 
