Compression Directions in Southern California

Comments to

These are results of observations from deviated boreholes in Southern California (from Santa Barbara to Los Angeles Basin). Borehole elongation in drill holes was used to infer breakout orientation and directions of maximum horizontal principal stress [Wilde and Stock, 1997]. These results are broadly consistent with results from focal mechanism studies [Hauksson, 1990] as well as breakout and focal mechanism data present in the world stress map database [Zoback, 1992]. Click on one of the next choices to see:

MAP OF LOS ANGELES AREA only

LOWER HEMISPHERE STEREOGRAPHIC PROJECTIONS OF BOREHOLE ELONGATION DIRECTIONS from all borehole studied , separated according to geographic region:

• SANTA BARBARA REGION

• UPPER OJAI VALLEY

• CENTRAL VENTURA BASIN

• EAST VENTURA BASIN / CENTRAL TRANSVERSE RANGES

• WEST LOS ANGELES BASIN

• EAST LOS ANGELES BASIN

MORE DETAILED DATA FOR EACH BOREHOLE STUDIED

• TABLE WITH LIST OF ALL BOREHOLES USED IN WILDE-STOCK STUDY WITH MORE INFORMATION ABOUT EACH BOREHOLE (latitude, longitude, township, range, section, mean breakout azimuth, depth range, breakout depth range).

• PLOTS SHOWING DIPMETER DATA AND PROCESSED RESULTS FOR ONE BOREHOLE AS AN EXAMPLE (caliper data, bitsize, breakout and borehole azimuth, relative bearing, and borehole deviation; as a function of depth).

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