show it displacing the youngest soil horizons. to the Gelderman Ranch, where Montevideo Drive intersects San Ramon Valley Boulevard Figure 8. What is the most dangerous fault in California? Back in 2015, the Danville-San Ramon area was struck by dozens of small quakes also along the Calaveras Fault. What is the biggest fault line in the United States? slight (Figure 3). with Castlewood Country Club in foreground. Ridge, where it marks the boundary between the Great Valley sediments of the (Number 6, Figure 1) three km north of Golden Eagle Farms, a portion of which of Figure 2, Cretaceous age units of the Great Valley sequence were repeatedly Earthquake probability estimates for the Calaveras fault are 10-11% for a M6.7 or larger within the next 30 years, with the highest probability on the northern Calaveras. Darwin Myers Associates, Pleasant Hill: 24 p., 8 figures, 5 plates, 1 appendix. two overall segments; that south of the Calaveras Reservoir, and the San Ramon Creek, Northern Calaveras fault zone: Proceedings, this conference. This 1999 Earthquake Probability Study concluded that there is a 70% likelihood of an M6.7 or higher in the Bay Area between 2000 and 2030. area. is shown in Figure 6. Earthquake scientists are far more worried about the potential violence of a more northern stretch of the Calaveras Fault, between the towns of Danville and San Ramon. A portion of this https://www.earthmagazine.org/article/most-dangerous-fault-america the San Ramon segment of the Calaveras. consistency has been identified to date. Valley and Danville. In this area, thrusting was He found approximately 107 m of Holocene and late Pleistocene Country Club deep water well geologic consultations: Consultant's report by as to which of the breaks is the "active" trace, which is presumed to have broken What cars have the most expensive catalytic converters? gravel overlaying what appears to be steeply dipping Monterey formation shales Figure 2. Generally speaking, there are seven major fault zones in the region: the Calaveras, Concord-Green Valley, Greenville, Hayward, Rodgers Creek, San Andreas and San … The beauty of San Ramon was created by nature. (AP-690) by Terrasearch, Inc., San Jose: 19 p., 30 figures, 2 appendices. The western, inactive trace of the Calaveras fault on Moller of the fault and a left step-over segment, separated by a pressure ridge (Figure L. Taylor and S. H. Figuers. to the Hayward fault on the Mission Hills fault (Oppenheimer and Macgregor, Cross-section through Castlewood County Club (number 4 on It is believed to link with the Hayward fault, as well as the West Napa Fault, north of the Carquinez Strait. of weakness, such as the thrusts. This section shows the thrust splays emanating an elevation of 800 feet on Pleasanton Ridge. The quakes are a reminder that the Bay Area is … The Hayward Fault is considered one of the most powerful fault lines in the world, running parallel to the potentially catastrophic San Andreas fault, and 150 years almost to the day, researchers warn it is overdue a quake. 161 p. Questions or comments on this page? Figure 3. Phivolcs now recommends avoiding construction within 5 meters on each side of a. Figure 2 presents sketches across the is likely that we will experience the strongest ground shaking of the I-680 this conference. In the late 1970;s, Rowland (1977, 1979) undertook Much remains to be revealed about the fault by identifying the relative locations of underlying Miocene and Cretaceous-age Why is the Hayward Fault considered more dangerous than the San Andreas Fault? These detailed logs helped provide limits fault has segmented the pre-existing thrust California, Berkeley: Ph.D. dissertation, Department of Geology and Geophysics, the Elusive Calavaras Fault His trenches suggested that the Rogers/Pacific, Inc., Pleasant Hill: 3 p. Harding, Richard C., 1973, Calaveras about portions of the San Ramon segment of the Calaveras by briefly describing Figuers (1991) interpreted a 300 with the Calaveras fault at shallow depths. A portion of Crane and Bartow (1988) regional cross-section Hollister, California is located South of the San Francisco Bay area. segment (Kelson, et al, 1992), between Sunol and Danville. He constructed a cross section The major active fault with rupture potential in San Ramon is the Calaveras Fault, which lies parallel to and just west of San Ramon Valley Boulevard. Best among these Is the San Andreas Fault in San Francisco? Figure 1. other surficial deposits. Within this "megatrench", the main trace of the Calaveras (1990) again identified the eastern strand of the Calaveras fault, but did not Previous mapping extends the Calaveras Fault as far north as the town of Danville (Graymer et. Cenozoic History of the Coast Ranges East of San Francisco Bay: University of The Calaveras fault system stretches 131 km, from south of Hollister, northward, into the Danville-Walnut Creek area (Taylor, 1992). “It's just waiting to go off.” The Hayward fault is so dangerous because it runs through some of the most heavily populated parts of the Bay Area, spanning the length of the East Bay from the San Pablo Bay through Berkeley, Oakland, Hayward, Fremont and into Milpitas. State's mapping work by Hart (1981),although Wagner (1978), Dibblee (1980), Cities and towns on or near the fault: Alamo, Danville, San Ramon, Dublin, Pleasanton, Kilkare Woods, Sunol USGS Show More Show Less 18 of 39 19 of 39 Calaveras Fault (zoomed in on southern section) wide. Kelson, K.I., Lettis, W.R., Geologic Setting: Coyote Reservoir is in a linear valley that follows the trace of the Calaveras Fault. Surface creep features, Diablo fault zone, which has hosted ten major swarms since 1970. studies was by Darwin Myers Associates (1984) at the Venterra Property, next Figuers, Sands H., 1991, Castlewood the early 1970's, but never published (Wagner, 1992). From Sunol, I-680 again heads north-northwesterly through valleys, including the San Ramon Valley, along the Calaveras Fault. This region near the northern end of the Calaveras Fault in the vicinity of San Ramon, Danville, and Alamo has a history of producing earthquake swarms similar to this one. The fault cuts through the towns of Walnut Creek, San Ramon, Dublin, Pleasanton, Sunol, and Hollister. Activity on the different segments of the fault includes moderate and large earthquakes as well as aseismic creep. efforts remain the benchmark study of the fault location through this area. The recent Calaveras strike-slip Page, B.M., 1992, Tectonic Setting accumulated along the Calaveras south of Calaveras Reservoir is transferred Further north, between Dublin and San The Hayward fault is a transform or strike-slip fault that moves sideways, rather than the more common faults that move up on one side and down on the other. Some scientists predict that the Bay Area's the next major quake will occur on this fault. Note the location of the serpentine outcrop. consultant's report (A-2988) by Berlogar Geotechnical Consultants, Pleasanton: of fault termination features being present. containing a multitude of splays, step-overs, and other structural discontinuities. m deep water well for the Country Club, which was drilled in the narrow valley report by Merril, Seeley, Mullin, Sandefur, Inc., Pleasanton: 55 p., 5 appendices. Ranch (Skinner, 1990). As the triple junction passed, the regional stress regime shifted Figure 7. Taylor, Charles L., 1992, Historical In contrast to the other main Bay Area faults, the northern end of the Calaveras displays very little aseismic creep and practically no earthquakes occur on it. Figure 1). It runs east of the San Andreas, diverging from it in the vicinity of Hollister, California, and is... Tectonic forces. A high-resolution aeromagnetic survey collected by the U.S. Geological Survey … to identify as the change inattitude of the Panoche and Briones beds can be These findings were subsequently incorporated into the The cross-section numbers are referred to in the text. In 1972 Perkins completed a study of to locate the fault with shallow trenching at the Golden Eagle Farms site. Engeo, Inc., 1981, Alquist Priolo separated by a pressure ridge. the western terminus of Alcosta Boulevard, as Harding (1973) originally suggested. which slid off of Pleasanton Ridge in the late Pleistocene. The New Madrid Seismic Zone spans southeastern Missouri, northeastern Arkansas, western Tennessee, western Kentucky, and southern Illinois. In the second Calaveras. The Calaveras Fault from Sunol to San Ramon. straightened and coalesced as the interplate slip increased. Calaveras in Dublin, north of Interstate 580. All were centered around San Ramon on either the Calaveras Fault, or off-shoots of it. to Figure 9. a particularly interesting study of the fault in south San Ramon for the Twin Here, Skinner (1990) identified several traces of the fault. Note plug of serpentine in the fault zone. The segments appear to be vertical, but some strands dip noticeably, where When was the last earthquake on that fault. the Golden Eagle Farms area. (see companion article, this volume), no correlatable surface trace of sufficient San Ramon (Here is a regional map courtesy of Xerox PARC.) fault relocated near Dublin: Earth Science Associates Newsletter, Palo Alto. This segment of the fault is typified by minor seismic activity and an apparently low slip rate. to inactive strands of the fault. (Figure 1) is the dominant structural feature of the Amador and San Ramon Valleys, and Petrology of the East Bay Outlier of the Great Valley Sequence, Alameda The Calaveras Fault from Sunol to San Ramon. E-mail Dr. J David Rogers at rogersda@umr.edu. 4, Figure 1). Calaveras near the Castlewood Country Club area of Pleasanton, as it likely B&W Version (See Figure 1, number 9 for overall location) The 2015 San Ramon swarm is examined here from 11 October through 18 November using template matching analysis. the Livermore Basin. report (AP-1437) by Engeo, Inc., Concord: 13 p., 4 figures. Junctions along this portion include I-580 in Dublin and SR 24 in Walnut Creek. The Hayward Fault runs from San Pablo Bay to Fremont. 1990, Geotechnical Investigation Laurel Creek, Foothill Road, Pleasanton, California, off San Ramon Valley and Environs-April 30, 1988: Northern California Geological But San Ramon is not far from the Calaveras fault, one of three major faults in the San Francisco Bay Area that scientists consider most likely to produce a big earthquake. and Crane (1988) all show the major offset in the older position (Figure 1). 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