common on the Hayward, Rodgers Creek and Concord faults, seems absent along That quake is estimated to have been about magnitude 6.8. According to the Bureau of Labor Statistics, the region is home to 87,000 businesses, 1.5 million jobs and quarterly wages nearing $25 billion; the Bay Area’s overall GDP would, if it were a separate country, rank as the 19th largest in the world. to corridor to date, and we will, in all likelihood, learn much more about the Seeley, Marc W., and Perkins, As shown in the Search: Add your article Home. Investigation on A Portion of the Bishop Ranch south of Bollinger Canyon Road Calaveras fault (Wagner, 1978). The Calaveras and San Antonio reservoirs store more than 180 million cubic meters of water, perched above the city of Fremont and its 224,000 residents. Crane, Ron, and Bartow, G.W., Nevertheless, given its structural position, Transportation problems will be felt immediately after the quake. Myers shows the two segments joining up with one another a short distance first regional, semi-balanced cross section through the area. Find what to do today, this weekend, or in February. north of Sunol, the Calaveras fault is well defined at the base of Pleasanton 3, 1861, causing continuous ground rupture, 6-8 miles long, between the Amador Instead of being a single strand, the Calaveras consists of two active traces Historically, the Calaveras Fault has produced much larger magnitude earthquakes, including in 1984, when a M=6.2 earthquake struck near Morgan Hill, resulting in over $7.5 million in damage. upper Monterey formation (Briones sandstone). Calaveras. to locate the fault with shallow trenching at the Golden Eagle Farms site. 4, Figure 1). The Calaveras Fault is a mostly right-lateral, strike-slip fault. area. Local governments could establish community caches of critical supplies — drinking water, food, medicine and tents, for example — in areas likely to be devastated by the shaking. Visit top-rated & must-see attractions. In much of the segment, its surface we can expect strong energy propagation and release along the segment when the for a series of small developments (Engeo, 1981, Figure 1). of Figure 2, Cretaceous age units of the Great Valley sequence were repeatedly The seismic hazard forced replacement of the original dam. Moller Ranch - One and a half km north, to identify as the change inattitude of the Panoche and Briones beds can be The most recent of these was a magnitude 6.2 earthquake near Morgan Hill in 1984. of weakness, such as the thrusts. Unusual seismic activity both on the Masbate fault and Central Leyte fault … and identification of the trace of the Calaveras was performed by Wagner in L. Taylor and S. H. Figuers. Note the location of the serpentine outcrop. on Geologic Investigation Moller Property, Foothill Boulevard, Pleasanton, California: A further problem is flooding. This multi-use trail can be used both directions and has a easy overall physical rating with a 245 ft blue climb. These quakes originate just east of the city on the creeping section of the Calaveras Fault, which is a major source of earthquake activity in Northern California. (See Figure 1, number 9 for overall location) In considering the surface expression on the eastern extent of the Calaveras. It’s just a matter of time before a large earthquake on the Hayward Fault happens, but how we choose to prepare — or not to prepare — will make a tremendous difference to those caught in the aftermath of this inevitable disaster. All of these are ``right-lateral strike-slip faults'', which means that the motion is predominantly horizontal, with the land on the West side of the fault moving North. fault has segmented the pre-existing thrust The north Central Leyte fault and the south Central Leyte fault, on the other hand, are characterized by aseismic creep and medium-sized events, usually with clusters of foreshocks, respectively. These quakes originate just east of the city on the creeping section of the Calaveras Fault, which is a major source of earthquake activity in Northern California. The HAZUS model estimates the death toll of a 2 p.m. quake would be five times greater than a quake occurring at 2 a.m. (The Kobe quake occurred before 6 a.m., as did the 1994 Northridge quake and the 1906 San Francisco quake. In so doing, it is likely that This “slip deficit” suggests that creep will not prevent future quakes, according to Kristy Tiampo, now at the University of Colorado at Boulder, and her colleagues, who explored the issue in a 2013 study in Earth and Planetary Science Letters. true character and extent of the San Ramon segment of the Calaveras fault. M.E., 1984, Preliminary Evaluation of Geologic Impacts on Land Development Capability, numbers are referred to in the text. California: consultant's report (AP-2248) by Terrasearch, Inc.,Dublin: 46 p., to the current mode of a strike-slip motion. and Crane (1988) all show the major offset in the older position (Figure 1). Calaveras, it does appear to have spawned a Magnitude 6.9 earthquake on July They can still remedy the mistakes of the past, however, in part by offering buyouts as an incentive to move people away from the worst zones. Darwin Myers Associates, Pleasant Hill: 24 p., 8 figures, 5 plates, 1 appendix. both the HF and the CF display active surface creep at spatially variable rates, indicating a complex distribu-tion of locked and shallow slipping patches. Schematic cross-sections across the study area. In 2001, the SFPUC lowered water levels in the reservoir to less than 40 percent of normal operating capacity in response to seismic concerns. . trace is uncertain because it appears to be buried beneath massive ancient landslides, The Calaveras and Hayward faults extend up the east side of the San Francisco Bay. the scene of numerous explorations in the 1980's. What is important to appreciate is that, in Best among these Note plug of serpentine in the fault zone. When it will happen is unknown, but the effects of such an event are quite clear: Major shaking to fragile infrastructure will result in loss of life and great economic damage. straightened and coalesced as the interplate slip increased. But creep on the Hayward Fault does allow us to map its trace precisely, and to see where large ruptures might happen when the fault does break again. South of the Bay Area the Hayward and Calaveras merge into the San Andreas. A portion of this to the Gelderman Ranch, where Montevideo Drive intersects San Ramon Valley Boulevard overall location of the Calaveras fault was Hurricane Harvey's most destructive force. Unfortunately, for the most part, such prudent preparations are not being made. Details of the Sunol-Castlewood County Club segment of the report (AP-1437) by Engeo, Inc., Concord: 13 p., 4 figures. Given the Hayward’s proximity to large populations, its rupture presents a huge risk. Wagner, J. Ross, 1978, Late The Xianshuihe Fault is located at the eastern boundary of the Tibetan Plateau and is one of the most active faults in China. Perkins, Michael E., 1972, Geology the ground surface in 1861. Figure 7. of the San Francisco Bay Region: Proceedings, this conference. It skirts the East Bay hills, then plunges into downtown Hayward, where it offsets the old Hayward City Hall, creating cracks in the walls and distinct offsets in the tile floor, and slices a retirement home. The location of this pod is also Figure 2 presents sketches across the Calaveras Fault. echelon strands within a zone varying from tens of meters to over 500 meters 1988, Structure Section D-D' to accompany Field Trip Guidebook: The Geology In this area, Myers (1984) found both the main trace B&W Version Not only are homebuyers not protected by any required disclosures in contracts, but there has also been a failure to prepare for the inevitability of this quake. Additionally, if freeway overpasses collapse or become too damaged for vehicles to travel underneath them safely, then freeways are rendered useless. At the extreme northeastern portion of the Moller Ranch, Skinner Figure 9. segment (Kelson, et al, 1992), between Sunol and Danville. consultant's report to Currin Construction Co.: 74 p., 6 figures, 3 appendices. with the Calaveras fault at shallow depths. Karen D’Souza is a writer for the Bay Area News Group papers, covering healthy living, Bay Area culture and other lifestyle topics. It is likely that the (Figure 4). which slid off of Pleasanton Ridge in the late Pleistocene. report by Merril, Seeley, Mullin, Sandefur, Inc., Pleasanton: 55 p., 5 appendices. (Figure 1) is the dominant structural feature of the Amador and San Ramon Valleys, In many parts of the Bay Area, these roadways represent the only feasible way to move between areas; freeways physically isolate some communities, with pedestrian movement impossible between them. Hydrogen (H 2) has been monitored continuously at 1.5‐m depth at nine sites along the San Andreas and Calaveras faults in central California since December 1980.Site characteristic small noninstrumental diurnal variations were recorded during quiescent periods at most sites. The 1995 Kobe quake, a magnitude-6.9 event in southern Japan, has been proposed as the best analogue for a future Hayward earthquake, which is expected to have a similar magnitude and may have a similar rupture length. The last significant quake on the Hayward Fault was in October 1868. Newton teaches geology at College of Marin in Kentfield, Calif. In San Leandro, the Hayward Fault runs near the Fairmont Hospital and the earthen dam holding back the Lake Chabot Reservoir. Unfortunately, it is also the prime water source for San Francisco. San Jose lies between the San Andreas Fault, the source of the 1989 Loma Prieta earthquake, and the Calaveras Fault.San Jose is shaken by moderate earthquakes on average one or two times a year. Most of the Bay Area’s water is impounded in reservoirs, in hills far out of sight and out of mind of the residents. These detailed logs helped provide limits 1. Creeks portion of the old Bishop Ranch (Number 10, Figure 1). to inactive strands of the fault. He constructed a cross section Thirty people in the region were killed by the quake while nearly every building in Hayward was damaged or destroyed. the Western Outlier of the Great Valley Sequence in the hills between the Hayward The San Ramon segment on the Moller Ranch (Number 7, Figure 1), the Calaveras makes a westerly bend. Figure 5. (Taylor, 1992). In my nearly two decades of teaching geology in the Bay Area, I have found that surprisingly few people even know where the fault is. © 2008-2021. The Bay Area fault system and the spot (red star) where the Hayward Fault branches off from the Calaveras Fault. In Berkeley, the fault runs beneath the University of California at Berkeley’s football stadium, where offset on the south wall can be seen. on a massive mega-landslide complex, comprised of Great Valley Sequence rocks This is the range of buildings damaged modeled by HAZUS for the three different magnitude scenarios: Assessing casualties is more challenging. The Hayward Fault splinters from the Calaveras Fault, which itself is an offshoot of the San Andreas Fault, near Hollister, south of the Bay Area. The western, inactive trace of the Calaveras fault on Moller State's mapping work by Hart (1981),although Wagner (1978), Dibblee (1980), For more information, click on the following phrases for a Google search: San Andreas fault map, San Andreas fault line, San Andreas fault pictures, San Andreas fault facts, San Andreas fault earthquake prediction, San Andreas fault zone. N., 1992, The Seismotectonics of the East San Francisco Bay Region: Proceedings, The Kobe quake also caused 1.5 meters of horizontal displacement on the ground; given the energy accumulated since the 1868 quake and the displacement observed in that event, scientists expect about 2 meters of horizontal displacement on the Hayward Fault, according to a 2008 fact sheet from USGS. In 1984, Seeley and Perkins Traveling over the water will be no less difficult; HAZUS estimates between 43 and 78 bridges will be damaged. many instances, the parallel, ancillary thrust features are more prominent than more pregnant segments just to the south rupture. of the Arroyo de la Laguna, at the toe of the ancient slide complex (Number However, the accumulated creep on these faults does not match estimates of stress expected to have accumulated on them, as Sarah Titus, now at Carleton College, and her colleagues demonstrated in a 2005 paper in Geology. For my model runs, I chose an arbitrary epicenter near the Lake Chabot Reservoir dam (which is one of many reservoirs located near the fault that could inundate neighborhoods if the dams fail). Oppenheimer, D.H. and Macgregor-Scott, shortening. study (Rowland, 1979),a large trench was excavated with scrappers, down to a The relocations reveal active secondary faults, which w At Welch Creek, the northern Calaveras fault crosses a series of fluvial terraces and displaces the intervening terrace risers. San Andreas Fault Homepage. strata (Figure 5). The science is clear: We know where the Hayward Fault is and we know it is going to rupture in the future. Active splays of the Calaveras Fault (Myers, 1984) near San one of controversy because the slide complex conceals the bedrock disconformity The western trace appears older On average it takes 14 minutes to complete this trail. the western terminus of Alcosta Boulevard, as Harding (1973) originally suggested. We find that the Calaveras Fault at depth is extremely thin, with an average upper bound on fault zone width of 75 m. Given the location error, however, this width is not resolvably different from zero. (see companion article, this volume), no correlatable surface trace of sufficient Most people have heard of the San Andreas, which they assume will be the source of the next big quake in the Bay Area, thanks in part to Hollywood disaster movies, such as the dreadful “San Andreas,” which perpetuate geologic absurdities. the Golden Eagle Farms area. Calaveras in Dublin, north of Interstate 580. He found approximately 107 m of Holocene and late Pleistocene The Calaveras Fault. (AP-690) by Terrasearch, Inc., San Jose: 19 p., 30 figures, 2 appendices. 32 figures, 3 appendices. thrust, as the block between the proto Hayward and Calaveras faults underwent The Calaveras Fault is continuous from the Sunol area south to Hollister. Figure 3. Country Club deep water well geologic consultations: Consultant's report by Some of the most important American technology companies are located near the Hayward Fault. The red line is the newly discovered surface trace connecting the southern end of the Hayward Fault to the Calaveras Fault, once thought to be an independent system. In 1973, Harding was among the first to study the When such events occur, it The white lines indicate faults recognized by the USGS. rotary borings to drill through the massive ancient landslide deposits blanketing Sufficient stress for a magnitude-6.7 quake is thought to have already accumulated, but recent research suggests even larger quakes are possible; in a 2015 paper in Geophysical Research Letters, Estelle Chaussard of the University at Buffalo and her colleagues suggested the Hayward and Calaveras faults are deeply connected, and thus a rupture could propagate along the two faults and produce quakes greater than magnitude 7. Here, Skinner (1990) identified several traces of the fault. to the Hayward fault on the Mission Hills fault (Oppenheimer and Macgregor, Rowland, Richard, 1988, Soil by a series of parallel offsets and stepovers, with scant reliable information (The latter gave its name to the fault when it was first recognized in 1895.) 161 p. Questions or comments on this page? East of San Francisco, across the muddy, green waters of San Francisco Bay, sits a smaller fracture in the crust: the Hayward Fault. The Calaveras Fault from Sunol to San Ramon. this conference. were among the first to utilize existing water well records (held by the Alameda If liquefaction damages even small sections of such freeways, they become unusable. The fault continues north, underneath residential areas and the campus of Contra Costa Community College. Despite the notoriety of the San Andreas Fault, it is not the greatest seismic threat to the Bay Area. One way to assess this question is to compare a potential large Hayward quake to events of similar size in areas of similar population. The Calaveras fault, part of the San Andreas fault system, is one of the most seismically active faults in central California. The Calaveras fault system runs over 80 miles, from south of Hollister … Johnson Ranch/Golden Eagle Farms - Just As shown in the upper half The article attracted a great deal of attention, especially among people who had never heard of the possibility that the heavily populated Pacific Northwest could, in a geologic moment, become “toast” — as someone quoted in the article put it. The Hetch Hetchy water system is extraordinarily vulnerable to seismic disruption. Underscoring this risk, the Calaveras Reservoir’s earthen dam, constructed in 1925, has been deemed so seismically vulnerable that a replacement dam farther downstream is currently under construction. Investigation, Venterra Property, City of San Ramon: Consultant's report by Perkins mapped the fault as two distinct strands, the The USGS continuously monitors their activity. The surface expression can be seen near the Fremont Main Library and the Fremont Police Department, as well as two hospitals. Since many of these bridges form choke-points in traffic flow, damage to even a few could create epic traffic jams. But if a quake occurred at 2 p.m. on a weekday, many people would be at work or school in vulnerable structures constructed with brick walls and unreinforced masonry. Applied Soil Mechanics, 1988, Figuers, Sands H., 1991, Castlewood The entrance to the Oakland Zoo is marked by the fault; the zoo even notes the location of the fault on its grounds with a sign. they cut pre-existing thrusts. Within this "megatrench", the main trace of the Calaveras Active faults at the base of the Sierra Nevada mountain range and within the basins to the east have caused damaging earthquakes in the past, such as the 1872 Owens Valley earthquake. We have no excuse not to prepare for the coming quake. On average it takes 27 minutes to complete this trail. His trenches suggested that the The Masbate fault is the central part with large and medium earthquakes accompanied by unusually large ground rupture. The potential threat is so severe, the owner of the Calaveras Reservoir decided to build a replacement dam. Wagner found a pod of serpentine separating the Panoche and Briones strata near Instead, the opposite is happening, and across the Bay Area, new homes are being built in fault zones with seemingly no consideration for what could happen to the people in them. The lower cross-section indicates and Geologic Investigation, Castleridge Development, Foothill Road, Pleasanton, fault relocated near Dublin: Earth Science Associates Newsletter, Palo Alto. This manuscript was reviewed by C. the early 1970's, but never published (Wagner, 1992). Figure 2. The northern segment of the Calaveras Fault is virtually locked and this segment of the fault creeps at a rate between 2 and 3 mm/yr. The Calaveras Fault is a major branch of the San Andreas Fault located in northern California in the San Francisco Bay Area.To the east of the Hayward-Rodgers Creek fault, the Calaveras fault extends 123 km, splaying from the San Andreas fault near Hollister and terminating at Danville at its northern end. Figure 6. the main trace of the fault. m deep water well for the Country Club, which was drilled in the narrow valley It was long believed that there was no connection between the Hayward Fault and the Calaveras, but geological studies (particularly the examination of very small and deep earthquakes) suggest that the two may be connected. Household gas meters could be required to have motion-activated automatic shut-off switches, a technology widely used in Japan to reduce post-quake fire danger. Ranch (Skinner, 1990). No vertical exaggeration. Society, San Ramon. But when might that risk become reality? The headquarters of Facebook and Google and Apple’s new “spaceship” campus are less than 20 kilometers away — all close enough for shaking to affect the operations of the companies. Long stretches of freeways in the Bay Area sit near sea level, built on marshy tidal flats that will almost certainly experience liquefaction during the quake. the toe of Pleasanton Ridge (Number 5, Figure 1), in an attempt to locate the The Calaveras and San Antonio reservoirs are part of the Hetch Hetchy water system, an improbable Rube Goldberg-like scheme to move water from the Sierra Nevada across the Central Valley, across the Calaveras Fault, across the Hayward Fault, across the liquefaction-vulnerable marshes of the southern bay, then into two long, linear sag ponds: the Crystal Springs and San Andreas reservoirs. Exploration, San Ramon Valley Methodist Church, San Ramon, California: consultant's (1990) again identified the eastern strand of the Calaveras fault, but did not 18 p., 24 plates, 1 appendix. Just as the citizens of the Pacific Northwest may one day find themselves affected by the Cascadia Subduction Zone, the Bay Area will be damaged by the Hayward Fault. consistency has been identified to date. This multi-use trail can be used both directions and has a moderate overall physical rating with a 1,057 ft green climb. off San Ramon Valley and Environs-April 30, 1988: Northern California Geological