|Data Series 138: Nebraska, Kansas, and Oklahoma Complete-Bouguer Gravity Anomaly Map|
The colors on this Bouguer gravity anomaly map represent gravity variations resulting from lateral density variations in the Earth. Positive anomalies (red colors) occur in areas with average density greater than the Bouguer reduction density of 2.67 g/cc, whereas negative anomalies (blue colors) occur in areas of lower density. The complete-Bouguer gravity anomaly grid was compiled using data from 109,828 gravity stations (some of them duplicate) in and adjacent to the States of Nebraska, Kansas, and Oklahoma. These data were extracted from the gravity database maintained by the National Geophysical Data Center (from Department of Defense unclassified data) (Hittleman and others, 1994). Observed gravity relative to the International Gravity Standardization Net 1971 (IGSN71) datum were reduced to the Bouguer anomaly using the 1967 gravity formula (Cordell and others, 1982) and a reduction density of 2.67 g/cc. Terrain corrections were calculated radially outward from each station to a distance of 167 km using a method developed by Plouff (1977). The data were converted to a 1,000-m grid using minimum curvature techniques and are displayed with an illumination from the northeast.
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