Approximate location of fault traces and historic surface ruptures within the Hayward fault zone between San Pablo and Warm Springs, California

Field trip guide to the Hayward Fault

“…Much has been learned in the last two decades, both about the precise location of the active fault trace and about the creeping behavior of the Hayward fault, since creep was first documented in the early 1960s (e.g., Cluffand Steinbrugge, 1966, Radbruch, 1967). However we still cannot say with much certainty when the next large earthquake is likely to occur on this fault In fact, if the 1868 and 1836 earthquakes were not in the historical record, scientific arguments could be made, using known rates of fault creep this century and regional strain from recent decades, that large earthquakes seem unlikely if not impossible.…”

Relative slope stability and land-use planning in the San Francisco Bay region, California

“…Publications in the 1950's dealt largely with particular aspects of the factors that controlled landsliding such as slope exposure (Beaty, 1956) (Bonilla, 1959), specific studies of individual landslides (Woods, 1958), and studies of slope stability at particular sites of development (Kachadoorian, 1956(Kachadoorian, , 1959. Several geologic maps published during this decade incorporated much engineering geologic data and were forerunners of recent types of engineering geologic maps (Radbruch, 1957;Schlocker and others, 1958). Numerous studies were completed in the 1960's, including an analysis of landslides in the San Francisco South quadrangle (Bonilla, 1960), a study of landslides in the Orinda Formation (Radbruch and Weiler, FIGU RE B.-Landslide damage to a road north of Cloverdale in Sonoma County.…”

“…The four most important factors that cause slope failures, and to which many other factors are related either directly or indirectly, are (1) the nature of the underlying bedrock or unconsolidated deposits, 2the angle of slope, (3) rainfall, and 4the presence of older landslide deposits, which can commonly become reactivated or continue to move intermittently over long periods of time. The San Francisco Bay region includes a wide variety of landforms that are underlain by many different types of bedrock (Schlocker, 1968(Schlocker, , 1970Brabb and others, 1971;Brabb and Pampeyan, 1972a;Dibblee, 1966Dibblee, , 1972aDibblee, , b, c and d, 1973aSims and others, 1973;Fox and others,1973;Blake and others, 1974) and unconsolidated deposits (Radbruch, 1957;Nichols and Wright, 1971;Helley and Brabb, 1971;Helley and others, 1972;Lajoie and others, 1974;Lajoie and Helley, 1975). The region includes very flat to very steep slopes (U.S. Geol.…”

“…Survey, 1972), has a broad range in annual rainfall (Rantz, 1971a, b, c), and contains many thousands of ancient landslide deposits . Earthquakes along the numerous active faults of the region are common and cause shaking of the ground, thus contributing to landsliding (Radbruch, 1967(Radbruch, , 1968Radbruch-Hall, 1974;Brown, 1970Brown, , 1972Brown and Lee, 1971;Burke and Helley, 1973;Sharpe, 1973;Sorg and McLaughlin, 1975;Sarna-Wojcicki and others, 1975;Wesson and others, 1975;Frizzell and Brown, 1976;Herd and Helley, 1976;Helley and Herd, 1977;Youd and Hoose,' 1978). The effects.of bedrock geology, slope, and ancient landslides on landsliding are discussed in more detail in a later section in conn~ction with the slopestability map.…”

Seismic hazards and land-use planning

“…FIGURE ll.-View showing approximate location of fault traces within a part of the Hayward fault zone, some of which ruptured during the October 21, 1868 earthquake(Radbruch, 1967). The plant nursery, undeveloped open space, freeway, and cemetery are land uses most compatible with the hazards posed by this active fault.…”