BAGC.m: Three dimensional gravity modeling software with an application in Southern Death Valley, CA

Brian Eugene Eslick, University of Texas at El Paso

Abstract

Basin Anomaly Gravity Calculator (BAGC.m) is a 3D interactive gravity modeling package designed to create, edit, and calculate the gravitational attraction of basin models entirely within the MATLAB™ environment. Gravity anomalies are calculated using the Rectangular Prism Method (Bott, 1960; Kane, 1962; and Plouff, 1966) which subdivides earth models into regularly spaced rectangular prisms. This approach requires large 3D matrices to store most realistic earth models. The process of model editing is simplified by storing basins as 2D gridded files which define the depth to the boundary between basement rock and sedimentary fill for each model cell. In order to minimize computation time, BAGC.m calculates and stores the gravitational attraction of each cell so that when the model is edited only those cells that change need to be recalculated.^ The performance of BAGC.m was tested by comparing the gravity anomaly produced by a modeled sphere of radius 4.5 km at a depth of 4.5 km with its analytical solution. The tests indicate that BAGC.m reproduces the analytical solution with an error of 0.6% for a sample spacing of 60 m which corresponds to 7.07x10-6% of the volume of the sphere. BAGC.m was used to calculate the gravitational attraction of a regional basin depth model of Death Valley developed by Blakely and Ponce (2001). Results were compared to a new high precision gravity data set and indicate that the structures within the Southern Death Valley Fault Zone (SDVFZ) are more complex than predicted by the regional basin depth model. However, the program did calculate the contributions of the basin fill to the regional gravity field based on that depth model. ^

Subject Area

Geophysics

Recommended Citation

Eslick, Brian Eugene, "BAGC.m: Three dimensional gravity modeling software with an application in Southern Death Valley, CA" (2010). ETD Collection for University of Texas, El Paso. AAI1483892.
http://digitalcommons.utep.edu/dissertations/AAI1483892

Share

COinS