Features and dimensions of the Hayward Fault Zone in the Strawberry and Blackberry Creek Area, Berkeley, California

Abstract

DISCLAIMERThis document was prepared as an account of w o k sponsored by the United States GOV-CIIL While this document is believed to conrain conact information, n d t h a the United States Govanmmt nor any agency thcrwf, nor The Regents of the Univclsity of California. nor any of their employctx. makcs any w-ty. Features and Dimensions of the Hayward fault zone in the Strawberry and Blackberry Creek area, Berkeley California IntroductionThis report presents an examination of the geometry of the Hayward fault adjacent to the Lawrence Berkeley Laboratory and University of California campuses in central Berkeley. The fault crosses inside the eastern border of the UC campus. Most subtle geomorphic (landform) expressions of the fault have been removed by development, and by the natural processes of landsliding and erosion. Some clear expressions of the fault remain however, and these are key to mapping the main trace through the campus area. In addition, original geomorphic evidence of the fault's location was recovered from large scale mapping of the site dating from 1873 to 1897. Before construction obscured and removed natural landforms, the fault was expressed by a linear, northwest-trending zone of fault-related geomorphic features. There existed well-defined and subtle stream offsets and beheaded channels, fault scarps, and a prominent "shutter ridge". To improve our confidence in fault locations interpreted from landforms, we referred to clear fault exposures revealed in trenching, revealed during the construction of the Foothill Housing Complex, and revealed along the length of the Lawson Adit mining tunnel. Also utilized were the locations of offset cultural features. At several locations across the study area, distress features in buildings and streets have been used to precisely locate the fault. Recent published mapping of the fault (Lienkaemper, 1992) was principally used for reference to evidence of the fault's location to the northwest and southeast

Distribution of aseismic slip rate on the Hayward fault inferred from seismic and geodetic data

“…Surface creep is observed along the entire length of the fault in the range of 3–9 mm/yr and the rates appear to be consistent over the past several decades [ Lienkaemper and Galehouse , 1997]. The geologic slip rate on the fault is estimated at ∼9 mm/yr [ Lienkaemper and Borchardt , 1996; Lienkaemper et al , 1991; Williams , 1995]. The difference between the geologic and contemporary creep rates suggests that a slip deficit exists, and that the accumulating elastic strain will presumably be released in future earthquakes.…”

Assessment of Fault-Creep Deformation at Memorial Stadium, University of California, Berkeley, California

“…Buwalda (1929) made key observations regarding the geomorphology and stratigraphy of lateral offset at the UC Berkeley campus both before and during construction of Memorial Stadium in 1923 and described the approximately 370 m (1,200 ft) right-lateral offset of the channel of Strawberry Creek, where it exits the Berkeley Hills. Some clear surface expressions of the fault remain, however, and good geomorphic evidence of the fault's location has been recovered from large-scale maps of the site that were completed in 1897, 1902, and 1922(Williams and Hosokawa, 1992Williams, 1995;Geomatrix Consultants, 2001). Some clear surface expressions of the fault remain, however, and good geomorphic evidence of the fault's location has been recovered from large-scale maps of the site that were completed in 1897, 1902, and 1922(Williams and Hosokawa, 1992Williams, 1995;Geomatrix Consultants, 2001).…”