Techniques
Micro Gravity Surveys
Gravimetry is a potential field technique which measures variations in the Earth's gravitational field. These variations are caused by density contrasts in the near surface rock and sediment. Gravimetric surveys are carried out using extremely sensitive instruments capable of measuring tiny variations in the gravitational field. These surveys are always carried out in conjunction with a precise topographic survey to enable terrain corrections.
Typical applications are:
Where micro-gravity is used
- Regional geological mapping
- Oil and gas exploration
- Mineral exploration
- Sediment thickness studies
- Archaeological surveys
- Void detection
Cavity and void detection
The technique is extensively used for cavity detection, along with other techniques of electrical imaging, GPR etc.
Reading gravity anomalies
Gravity measurements define anomalous density within the Earth; in most cases, ground-based gravimeters are used to precisely measure variations in the gravity field. Gravity anomalies are computed by subtracting a regional field from the measured field, which results in gravitational anomalies that correlate with source body density variations. Positive gravity anomalies are associated with shallow high density bodies, whereas gravity lows are associated with shallow low density bodies. Thus, cavities and voids can be readily detected using micro-gravity surveys.
