Description
This thesis is a feasibility study of the use of micro-gravity in fault reconnaissance in the urban San Diego, California, area. Gravity readings were collected on nine profiles in downtown and Old Town San Diego. The results from downtown show the capability of the micro-gravity method by detecting the near-surface density contrast associated with the 13th Street Fault between E Street and Island Street. South of E Street, the gravity suggests the main contrast steps east from 13th Street, and remains midway between 14th and 15 Streets on the G Street profile and profiles further south. The Old Town profiles tended to show deeper contrasts and correlated well with the most recent fault maps of the area. The optimum station spacing for a project of this scale is 50 ft (15.2 m) and station elevations have to be known to 0.1 ft (0.03 m). The labor required for this study averaged 15 man hours per thousand feet of profile for field work, reduction, and qualitative interpretation. Given the cost and permitting requirements needed for exploratory drilling and exploratory trenching, a micro-gravity survey is a cost - effective method for fault reconnaissance.
