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ATTACHMENT F:MAPS AND CROSS SECTIONS OF GEOLOGIC STRUCTURE OF AREA former Rio Vista Gas Field,located 12 to 15 miles to the northwest of the STIG-LEC facility (Trautz et al,2007). The STIG-1 well boring intentionally did not penetrate the bottom of the unit. Based on the isopach map (Figure F-12),the estimated thickness of the Capay Formation is 150 feet. Seismic Activity The general region that surrounds the STIG#1 proposed injection site is characterized by a very low level of seismic activity. No active faults are mapped within 25 miles of this site. As shown in Figure F-13,the most recent earthquake nearby occurred on the Greenville Fault,located approximately 30 miles west of STIG #1 (Jennings and Saucedo, 1999). The Antioch Fault,another potentially active fault,is located near the Greenville Fault. No other known active faults are located within 50 miles of the site. The potential shaking hazard resulting from seismic activity near the site is estimated from information available on the California Geological Survey Web site (http://redirect.conservation.ca. og v/cgs/rghm/pshamag/pshamain.html). The STIG-LEC facility is located in an area that can expect between 10 to 20 percent peak ground acceleration. This is a relatively low seismic shaking potential. In addition to the review of active local and regional faults, existing information on subsurface faulting of the injection formation and the upper and lower confining units was assessed using DOGGR maps and cross-sections of existing oil and gas fields (DOGGR 1982). Based on cross sections constructed through the Lodi Airport and Harte gas fields (3 and 4-1/2 miles southeast from the STIG-LEC site,respectively),local faulting in both areas is assumed (Figure F-14). Based on the productive history of these sites,the faults created structural traps for local hydrocarbons and,therefore, are likely not conduits of gas or fluid migration.Faults are not known to be present within the AOR,based on local geophysical log information used to develop the Domengine Formation structural map for the 1993 permit (Figure F-10). SAC/371322/082550021(ATTACH MENT-F.DOC) F-5