Bouguer Gravity Map of Ohio

Basic Information
Author: Timothy E. Leftwich
Description:The gravity map after the application of latitude, free-air, and terrain corrections is the so called Bouguer map (Fig). Because the terrain gravity effects and the gravity effects of the Moho density contrast largely cancel each other for isostatically compensated crust, removal of the terrain effects for crust that is compensated generally creates Bouguer anomalies that are small in amplitude. Because this reduced form of gravity data mostly reflects the density variations in the Earth, this is the usual form that gravity anomaly results are presented in (Nettleton, 1971). The Bouguer gravity map reflects the reduced free-air gravity observations minus the gravity effects of the terrain. Areas with high positive topographic relief produce strong positive terrain gravity effects that result in negative Bouguer anomalies. On the other hand where the terrain gravity effect is small relative to the gravity effects of relatively dense crust, the Bouguer anomalies are relatively more positive. Additional information on how gravity is measured and corrected can be found in Blakely (1996). Herein, we show the CBA map of Ohio from EPRI (2012) data. The EPRI gravity anomaly data sets are compiled from several public domain and unpublished sources that were used in the central and eastern U.S. seismic source characterization (CEUS-SSC) project. These data are given in units of milligals (mGal). The average Earth gravity acceleration is roughly 980,000 mGal. A principal survey used in the Ohio region is that of Heiskanen and Uotila (1957) wherein they report that errors in the gravity measurements are generally less than 0.1 mGal. These EPRI data were selected for Ohio and regridded by cubic spline to 0.001 by 0.001 degree in WGS 84 Projection. This resource was provided by the Ohio Department of Natural Resources - Division of Geological Survey and made available for distribution through the National Geothermal Data System.
Publication Date:
Author Contact Information
Distributor Contact Information
Name: Customer Service Representative
Organization Name: Ohio Division of Geological Survey Geologic Records Center
Street: 2045 Morse Road, Bldg C-1
City: Columbus
State: OH
Zip: 43229-6693
Phone: 614-265-6576
Geographic Extent
North Bounding Latitude: 42.6016199443
South Bounding Latitude: 38.2209197668
East Bounding Longitude: -80.1123046875
West Bounding Longitude: -85.2099609375