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Open-File Report 00-193

Principal Facts for Gravity Stations in the Vicinity of San Bernardino, Southern California

By Megan L. Anderson, Carter W. Roberts, and Robert C. Jachens

Thumbnail of and link to report PDF (3.3 MB)Abstract

New gravity measurements in the vicinity of San Bernardino, California were collected to help define the characteristics of the Rialto-Colton fault. The data were processed using standard reduction formulas and parameters. Rock properties such as lithology, magnetic susceptibility and density also were measured at several locations. Rock property measurements will be helpful for future modeling and density inversion calculations from the gravity data. On both the Bouguer and isostatic gravity maps, a prominent, 13-km long (8 mi), approximately 1-km (0.62 mi) wide gradient with an amplitude of 7 mGal, down to the northeast, is interpreted as the gravity expression of the Rialto-Colton fault. The gravity gradient strikes in a northwest direction and runs from the San Jacinto fault zone at its south end to San Sevine Canyon at the foot of the San Gabriel mountains at its north end. The Rialto-Colton fault has experienced both right-lateral strike-slip and normal fault motion that has offset basement rocks; therefore it is interpreted as a major, through-going fault.

First posted May 27, 2007

Refer to the Readme and Metadata files for more information.

For additional information, contact:
Geology, Minerals, Energy, and Geophysics Science Center
U.S. Geological Survey
345 Middlefield Road, MS 901
Menlo Park, CA 94025-3591
http://geomaps.wr.usgs.gov/gmeg/

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Suggested citation:

Anderson, Megan L., Roberts, Carter W., and Jachens, Robert C., 2001, Principal Facts for Gravity Stations in the Vicinity of San Bernardino, Southern California: U.S. Geological Survey Open-File Report 00-193, 23 pp., https://pubs.usgs.gov/of/2000/0193/.



Contents

Abstract

Introduction

Gravity Data

Horizontal and Vertical Control

Data Reduction

Physical Property Measurements

Sources of Error

Preliminary Gravity Map Interpretation

Conclusions

Acknowledgments


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