Gravity Theory Measurement practices –Relative –Closed loops Corrections –Drift –Free Air –Bouguer –Terrain Interpretation –Modeling

Worden Gravimeter

Inside the Worden

Closing the Loop

Elevation Corrections Free Air Correction Bouguer Correction

Gravity Corrections Drift Correction (t obs -t base ) x drift rate Free Air Correction (h obs -h base ) * mgal/m Bouguer Correction (h obs -h base ) *  mgal/m where  = density in gr/cc

Gravity Anomalies Free Air Anomaly  g fa = (g obs -g base ) – (drift corr) + (fa corr) Bouguer Anomaly  g b =  g fa –(bouguer correction)

Gravity Corrections (sample)