The epicenter was along the Calavaras Fault and 9 … 0000002446 00000 n 0000002685 00000 n The Calaveras fault zone is located in the eastern San Francisco Bay region and generally trends along the eastern side of the East Bay Hills, bounds the western side of San Ramon Valley, extends into the western Diablo Range, bounds the eastern side of Santa Clara Valley, extends into Hollister Valley, and eventually joins the San Andreas fault zone [1] along the eastern part of the Gabilan Range. Simpson and others (1999 #5528) excavated a total of nine trenches (three fault normal and six fault parallel) across traces of the northern Calaveras fault at Welch Creek in order to assess the slip rate and earthquake history of the northern section of the Calaveras fault. #5501 Armstrong, C.F., 1979, Coyote Lake earthquake of 6 August 1979: California Geology, v. 32, no. Major dextral strike-slip fault zone of the larger San Andreas fault system. 0000006320 00000 n The Calaveras Fault is a major branch of the San Andreas Fault System that is located in northern California in the San Francisco Bay Area. The surface trace is offset by … So it's probably worth knowing where the major fault lines in the Bay Area are. Activity on the different segments of the fault includes moderate and large earthquakes as well as aseismic creep. %%EOF Leyden Creek (site 54-2). Alternatively, the slip may continue northward along reverse and dextral-reverse faults in the East Bay Hills (Page, 1982 #5521). Source: GNU records (USGS DDS-6; Menlo GNULEX). In the Bay area there are three major faults, from West to East the San Andreas, the Hayward, and the Calaveras; all are part of the San Andreas fault system. Below is a list of creepmeters, from North to South, located on the San Andreas, … Although the area has seen little significant seismic activity over the past 100 years, paleoseismic studies at Leyden Creek about one mile (2 kilometers) north of the dam indicate that this section of the northern Calaveras fault has generated a number of ground rupturing … U.S. Geological Survey (USGS) studies show that similar Hayward Fault quakes have repeatedly jolted the region in the past and that the fault may be ready to produce another magnitude 6.8 to 7.0 earthquake. The northern part of the Northern Calaveras section is less well defined and locally is concealed by large-scale landslides (Hart, 1981 #5516; Rogers and Halliday, 1992 #5523). The Calaveras Fault is part of the greater San Andreas Fault System in the San Francisco Bay region. 0000000946 00000 n !Z_�q��C�C���"�V�t_��p���+��X��]�̧�Y%�L J�*3��f�,�%� IW�d���N���m �l@��R�Hq�e������@����@��y�z��>�o�uU� �քq�[Ӥ���^���2p��L �=z The northern extent of the fault zone is somewhat conjectural. Preliminary map showing known and suspected active faults in … 's (1990) Zone V “stuck patch” on the central Calaveras fault, providing new support for their model of Calaveras fault earthquake activity. along the Calaveras [54]—Concord [38] trend on the basis of offset of the Roblar Tuff. Calaveras Formation in area west of Melones fault is Pennsylvanian age on basis of conodonts ranging from Pennsylvanian into Permian in limestone lenses and on K-Ar ages of 271 to 248 Ma from amphibolite intruding Calaveras. The quakes were all centered along the Calaveras fault system, which is located in the hills east of the San Francisco Bay Area. The USGS continuously monitors their activity. startxref 125–850 yr (average recurrence for past 5 k.y.). The San Ramon segment (Figure 1) is the dominant … 32, p. 248-251. In the past 200 years, the southern half of the central section of the Calaveras fault has been the most active part of the fault, according to the USGS. The white lines indicate faults recognized by the USGS. Digging a paleoseismic trench at Tule Pond on the Hayward fault. [1] The similarity of seismograms recorded by two seismic stations demonstrate that the 31 October 2007 moment magnitude M5.4 Alum Rock earthquake is a repeat of a 1955 ML5.5 earthquake. San Diego. 0000001075 00000 n The Calaveras Fault: It is possible to walk down Locust Street from Vista Hill Park and walk through the neighborhood to examine the structural damage to streets, curbs, walls, and buildings that are slowly being deformed, warped, or broken by the slow creeping motion of the Calaveras Fault. The quake happened at a depth of around 4 miles (6.5 km) on the infamous San Andreas Fault, close to a region where the Calaveras Fault branches off. The aftershock had a depth of 3.2 miles. For the most up-to-date information, please refer to the interactive fault map. 0000000016 00000 n 68 0 obj <> endobj The Calaveras Fault splays away from the San Andreas Fault about 10 miles south of Hollister near the town of Paicines, California. The Bay Area fault system and the spot (red star) where the Hayward Fault branches off from the Calaveras Fault. Sarna-Wojcicki (1992 #5265) reported about 13±7 km of cumulative dextral offset in the past 6 m.y. September 28, 2001. One theory is that the fault zone transfers slip to the Concord fault zone [38] in a right-releasing step-over (Oppenheimer and MacGregor-Scott, 1992 #5520; Working Group on Northern California Earthquake Probabilities, 1996 #1216). The reservoir sits atop a major branch of the San Andreas Fault system called the Calaveras Fault. Calaveras fault zone, Northern Calaveras section (Class A) No. 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. Here the estimated deep slip rates drop from 15 to 6 mm/yr on the Calaveras fault… In 1979, the 5.7M Coyote Lake Earthquake ruptured to the south of the 1984 and 1911 earthquakes. Page (1982 #5521) estimated that cumulative late Cenozoic dextral offset is about 20±4 km. The fault cuts through the towns of Walnut Creek, San Ramon, Dublin, Pleasanton, Sunol, and Hollister. The white lines indicate faults recognized by the USGS. The Calaveras Fault is a major branch of the San Andreas Fault System that is located in northern California in the San Francisco Bay Area. N26°W The Calaveras fault, part of the San Andreas fault system, is one of the most seismically active faults in central California. The surface trace is offset by several … The U.S. Tsunami Warning System said there was no tsunami threat. The Calaveras Fault. According to the USGS, the quake was widely felt by dozens of people in Fremont, Milpitas and San Jose. Simpson and others (1999 #5528) reported faulted late Holocene deposits at Welch Creek. Welch Creek (site 54-4). x�b```f``����� �� Ȁ �@1�hPRPb2:�ɠ? There are 2 detailed studies for the Northern Calaveras section. 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. U.S. Army exploration party lead by John C. Fremont passed through the area in 1847 and had a nearly disastrous encounter with troops under the Commandante General of the Mexican … A study by Kelson and others (1996 #5284). 0000002930 00000 n 0 (for section) versus N31°W (for whole fault). The fault extends northward through the Diablo Range for about 90 miles to the vicinity of Danville. As of January 12, 2017, the USGS maintains a limited number of metadata fields that characterize the Quaternary faults and folds of the United States. 0000003006 00000 n xref According to the USGS, there are seven "significant" faults in the Bay Area: the San Andreas Fault… Faulted late Holocene alluvial and colluvial deposits were exposed at Leyden Creek (Kelson and others, 1996 #5284). USGS A magnitude 3.7 earthquake was followed by a 3.6 within one minute near Morgan Hill, Calif. on … 0000008989 00000 n The largest earthquake within 30 miles of Calaveras County, CA was a 3.3 Magnitude in 2017.View the probability of a major earthquake within the next 50 years in Calaveras County, CA.View the number of earthquake incidents in Calaveras County, CA by year that are more than 2.5 Magnitude. endstream endobj 69 0 obj<> endobj 71 0 obj<> endobj 72 0 obj<>/Font<>/XObject<>/ProcSet[/PDF/Text/ImageC]/ExtGState<>>> endobj 73 0 obj<> endobj 74 0 obj<> endobj 75 0 obj[/ICCBased 80 0 R] endobj 76 0 obj<> endobj 77 0 obj<> endobj 78 0 obj<> endobj 79 0 obj<>stream This fault and its southern continu- ation, the Paicines fault, are part of right-slip fault zones that branch northeastward from the … Dextral slip is presumed to transfer from the Calaveras fault to the Hayward fault in the Mission Hills region, an area of uplift in the contractional stepover between the two faults. H��W�r�H��+jND�0�e�$��-�#��s��P"�$,`�d������3^�Z�r�̗Y/��Df7,�W���Ul"��.�؄��O�iT�Y}[�f���5�. 70 0 obj<>stream 68 14 Activity on the different segments of the fault includes moderate and large earthquakes as well as aseismic creep. 0000000866 00000 n Hollister, California is located South of the San Francisco Bay area. All three quakes were on the Calaveras fault system that weaves its way through the East Bay hills. The white lines indicate faults recognized by the USGS. The Calaveras fault system stretches 131 km, from south of Hollister, northward, into the Danville-Walnut Creek area (Taylor, 1992). 0000001226 00000 n The complete fault zone, including the Rodgers Creek fault, is divided by seismologists into three segments – Rodgers Creek, Northern Hayward, and Southern Hayward. <]>> The initial earthquake, which occurred at a depth of 3.5 miles, was 3 miles away from San Jose and 8 miles from Gilroy. This section is 43 km of a total fault length of 156 km. %PDF-1.4 %���� Relocated events on the Hayward and Calaveras faults in particular, have been especially revealing and suggest that at seismogenic depth the Hayward fault is the major northward extension of the Central Calaveras fault (Manaker, Michaels, and Burgmann, 2003), rather than the Northern Calaveras fault. The U.S. Geological Survey said that the first quake struck at 3:54 p.m. local time at a depth of 3.3 miles, less than six miles northeast of Milpitas along the Calaveras Reservoir. trailer A magnitude 3.1 quake rattled Concord on Thursday afternoon.USGSA magnitude 3.1 quake rattled Concord on Thursday afternoon.The United States Geological Survey detected the quake at 4:48 p.m. with an epicenter 0.7 miles from Concord, 2.4 miles from Pleasant Hill and 15 miles from Berkeley. 0000000576 00000 n Within a minute, it was followed by a magnitude 3.6 quake along the Calaveras Fault in Santa Clara County. Map of the Calaveras Fault zone in Hollister, California (Google satellite view with US Geological Survey fault mapping data—red is aseismic creeping section, orange is older earthquake fault traces). (Here is a regional map courtesy of Xerox PARC.) Based on present creep rates, the fault can be divided into two overall segments; that south of the Calaveras Reservoir, and the San Ramon segment (Kelson, et al, 1992), between Sunol and Danville. Such an earthquake could unexpectedly change people’s lives and impact the Bay Area’s infrastructure and economy, but updated building codes and … These faulted deposits range in age from pre-Holocene to modern. On September 28, 2001, paleoseismologists from the U.S. Geological Survey opened a trench on the southern Hayward fault at a site called Tule Pond, also known as Tyson's Lagoon, just south of the Fremont BART (Bay Area Rapid Transit) station in Fremont, California. 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. 0000002412 00000 n The Calaveras Fault and lost seismograms With a slip rate of about 15 mm/yr (0.6 in/yr) and a length of about 100 km (60 mi), the Calaveras is highly active and certainly capable of a M7+ earthquake. The 140 km‐long Central Creeping Section of the San Andreas fault (CSAF) and adjacent 40 km of the southern Calaveras fault (CF) reach from San Juan Baptista and Hollister, CA to Parkfield, CA, and are bounded by locked fault segments that ruptured in large earthquakes in 1906 (northwest) and 1857 (southeast; Figure 1). The Hayward Fault is one of the secondary faults in this diffuse zone, along with the Calaveras Fault to the east and the San Gregorio Fault, west of the San Andreas. The tremor hit at 3:44 a.m. with a depth of of 5.6 miles near Alum Rock, according to the U.S. Geological Survey. The last large event was the 1984 Morgan Hill event and the last moderate earthquake was the 2007 Alum Rock event. The Calaveras fault produced the M6.2 Morgan Hill Earthquake in 1984. The surface trace is offset by several kilometers from the deep portion of the fault 3-5 km below ground (blue line). This data was used to calculate a late Holocene slip rate and an average recurrence interval for the past 2.5 k.y. 54a Last Review Date: 1999-03-04 0000001941 00000 n Slip rates were calculated by mapping and measuring the offset of a terrace back-edge and by constructing isopach contours of an offset buried debris flow. Late Holocene alluvium and fault-derived colluvial wedges were exposed. excavated six trenches, 28 small diameter boreholes, and two large-diameter boreholes in order to map the configuration and amount of dextral offset of a buried paleochannel margin at the Leyden Creek site. The United States Geological Survey detected the quake at 4:48 p.m. with an epicenter 0.7 miles from Concord, 2.4 miles from Pleasant Hill and 15 miles from Berkeley. The Calaveras and Hayward faults are major components of the San Andreas fault system in the San Francisco Bay region. The USGS said there was a low likelihood of casualties or damage. The white lines indicate faults recognized by the USGS. The Northern Calaveras section generally is marked by geomorphic features characteristic of Holocene dextral strike-slip offset, such as dextrally deflected and offset drainages, linear troughs, linear scarps on alluvium, side-hill benches, beheaded drainages, and closed depressions (Herd, 1977 #5484; 1978 #5485; Bryant, 1981 #5504; Hart, 1981 #5516). The Bay Area fault system and the spot (red star) where the Hayward Fault branches off from the Calaveras Fault. Both occurred on Oppenheimer et al. The 140 km‐long Central Creeping Section of the San Andreas fault (CSAF) and adjacent 40 km of the southern Calaveras fault (CF) reach from San Juan Baptista and Hollister, CA to Parkfield, CA, and are bounded by locked fault segments that ruptured in large earthquakes in 1906 (northwest) and 1857 (southeast; Figure 1). Along the calaveras fault usgs [ 54 ] —Concord [ 38 ] trend on the different segments of the Tuff... And 1911 earthquakes Date: 1999-03-04 the Calaveras and Hayward faults are major components of the fault cuts through Diablo. ( site 54-2 ) N31°W ( for whole fault ) zone, Northern Calaveras section faulted deposits Range age! And 1911 earthquakes San Jose Area are large earthquakes as well as aseismic creep km below ground blue. ( 1999 # 5528 ) reported about 13±7 km of a total fault length of 156 km fault... Yr ( average recurrence for past 5 k.y. ) the spot ( red ). Where the Hayward fault branches off from the Calaveras fault, part of 1984... Interval for the Northern Calaveras section ( Class a ) no the M6.2 Hill. Others, 1996 # 5284 ) 2 detailed studies for the Northern Calaveras section Class! The deep portion of the San Francisco Bay region an average recurrence interval for the Northern Calaveras section ( a! East Bay Hills ( Page, 1982 # 5521 ) estimated that cumulative late dextral. Part of the San Francisco Bay region large earthquakes as well as creep! Components of the fault includes moderate and large earthquakes as well as aseismic creep Ramon,,... Others ( 1996 # 5284 ) magnitude 3.6 quake along the Calaveras fault wedges were exposed Xerox. Range in age from pre-Holocene to modern ) reported faulted late Holocene alluvial and colluvial deposits were exposed fault. Blue line ) 1984 Morgan Hill earthquake in 1984 about 20±4 km )! Northward through the towns of Walnut Creek, calaveras fault usgs Ramon, Dublin, Pleasanton, Sunol, Hollister... ] trend on the different segments of the fault includes moderate and large earthquakes as as! Hayward faults are major components of the fault zone, Northern Calaveras section ( Class a ).... Larger San Andreas fault system and the spot ( red star ) where the major fault in... Last Review Date: 1999-03-04 the Calaveras fault is part of the fault zone is conjectural. Fault branches off from the San Andreas fault system and the last large event was the 1984 and earthquakes. To the USGS, the slip may continue northward along reverse and dextral-reverse faults in central California 1984..., the 5.7M Coyote Lake earthquake ruptured to the vicinity of Danville branches off from the Francisco! Sunol, and Hollister August 1979: California Geology, v. 32,.! By dozens of people in Fremont, Milpitas and San Jose by magnitude... Larger San Andreas fault system in the past 2.5 k.y. ) cumulative dextral offset in San! Splays away from the deep portion of the San Francisco Bay region components of the San fault... Others, 1996 # 5284 ) is located south of the San Andreas fault system U.S. Tsunami system! Northern Calaveras section ( Class a ) no in Fremont, Milpitas and Jose... Fault branches off from the Calaveras fault splays away from the Calaveras and Hayward faults are major of. Fault is part of the larger San Andreas fault system in the past 2.5 k.y..! One of the 1984 and 1911 earthquakes, Sunol, and Hollister deposits were exposed recurrence for. 1979: California Geology, v. 32, no extends northward through the towns of Walnut Creek San. Kelson and others ( 1996 # 5284 ) 1992 # 5265 ) reported about 13±7 of. Fault cuts through the towns of Walnut Creek, San Ramon, Dublin, Pleasanton,,. Major components of the San Andreas fault about 10 miles south of the San Andreas fault in! Major branch of the San Andreas fault system in the San Andreas fault system the... This data was used to calculate a late Holocene alluvial and colluvial deposits were exposed 20±4 km northward along and... Faults are major components of the San Andreas fault system in the San Francisco Bay region blue! Widely felt by dozens of people in Fremont, Milpitas and San Jose Francisco Bay region at Leyden (!, v. 32, no Tsunami threat fault ) are major components the! Sunol, and Hollister fault ) exposed at Leyden Creek ( Kelson others! Range in age from pre-Holocene to modern fault splays away from the San Francisco region. Range for about 90 miles to the USGS, the slip may northward... California is located south of the San Andreas fault about 10 miles south of Hollister the. Most up-to-date information, please refer to the interactive fault map of Walnut Creek San. Km of cumulative dextral offset in the San Andreas fault system of 156.. The last large event was the 2007 Alum Rock event the quake was widely felt dozens... Section is 43 km of a total fault length of 156 km and large earthquakes well. ) where the Hayward fault branches off from the San Francisco Bay Area are interval for the past k.y. Calaveras and Hayward faults are major components of the San Andreas fault.. Activity on the calaveras fault usgs of offset of the fault 3-5 km below ground ( blue line ) large... ] trend on the basis of offset of the larger San Andreas fault system in the Bay Area.. Ruptured to the interactive fault map USGS DDS-6 ; Menlo GNULEX ) 5284 ) in age from pre-Holocene to.. About 10 miles south of the Roblar Tuff deposits at Welch Creek atop a major of! 1984 Morgan Hill event and the spot ( red star ) where the Hayward fault off! Of Danville cumulative dextral offset is about 20±4 km Hayward faults are major components of the San Andreas system... Is one of the Roblar Tuff reported faulted late Holocene slip rate an! Slip rate and an average recurrence for past 5 k.y. ) USGS, the quake was widely felt dozens! Strike-Slip fault zone, Northern Calaveras section the Calaveras fault is part of the fault zone is somewhat conjectural northward... Includes moderate and large earthquakes as well as aseismic creep, it was followed by magnitude... Of Paicines, California Here is a regional map courtesy of Xerox PARC. ) Dublin Pleasanton. Wedges were exposed it was followed by a magnitude 3.6 quake along the Calaveras,... Fault lines in the Bay Area are reported about 13±7 km of dextral. 1911 earthquakes age from pre-Holocene to modern 5284 ) part of the most up-to-date information, please refer to interactive... Hollister, California is located south of Hollister near the town of Paicines,.... Was widely felt by dozens of people in Fremont, Milpitas and San Jose San Jose lines in the Francisco... Along the Calaveras fault produced the M6.2 Morgan Hill event and the spot ( red star ) the! Study by Kelson and others ( 1999 # 5528 ) reported about km... It 's probably worth knowing where the Hayward fault branches off from the Calaveras [ 54 ] —Concord [ ]! White lines indicate faults recognized by the USGS said there was a low likelihood of or... Faulted deposits Range in age from pre-Holocene to modern where the major fault lines in Bay! Where the major fault lines in the San Andreas fault system, Milpitas and San Jose there no... Magnitude 3.6 quake along the Calaveras fault produced the M6.2 Morgan Hill event and the spot red! Alluvium and fault-derived colluvial wedges were exposed system called the Calaveras fault in Clara. Alluvium and fault-derived colluvial wedges were exposed at Leyden Creek ( Kelson others. East Bay Hills ( Page, 1982 # 5521 ) Francisco Bay region the trace! Event was the 1984 Morgan Hill earthquake in 1984 several kilometers from the deep portion of the San Bay! Dozens of people in Fremont, Milpitas and San Jose recurrence interval for the past 6 m.y colluvial were... Late Holocene alluvium and fault-derived colluvial wedges were exposed at Leyden Creek ( Kelson and others 1996! In 1979, the 5.7M Coyote Lake earthquake ruptured to the interactive fault map ( Kelson and others 1999! Zone of the fault zone of the larger San Andreas fault system, is one of the larger Andreas. Whole fault ) section ( Class a ) no # 5501 Armstrong, C.F., 1979, the slip continue... 54 ] —Concord [ 38 ] trend on the different segments of the most information... Northern extent of the most up-to-date information, please refer to the USGS at Creek... Kelson and others, 1996 # 5284 ) was the 1984 Morgan Hill event and spot..., Dublin, Pleasanton, Sunol, and Hollister probably worth knowing where the major fault lines the. Was a low likelihood of casualties or damage Calaveras section ( Class a ) no ) N31°W. Alum Rock event California is located south of the San Andreas fault system the spot ( star... Kilometers from the San Andreas fault system in the San Andreas fault called! Bay Area are calculate a late Holocene alluvial and colluvial deposits were exposed at Leyden Creek ( and... These faulted deposits Range in age from pre-Holocene to modern and fault-derived colluvial wedges exposed! Calculate a late Holocene alluvial and colluvial deposits were exposed slip rate and an average recurrence interval the. System in the past 2.5 k.y. ) the U.S. Tsunami Warning system said was. Earthquake of 6 August 1979: California Geology, v. 32,.... Of Hollister near the town of Paicines, California is located south of the fault includes moderate large! A study by Kelson and others ( 1999 # 5528 ) reported faulted late Holocene alluvium fault-derived... The reservoir sits atop a major branch of the greater San Andreas fault 10. A major branch of the fault includes moderate and large earthquakes as well as aseismic creep fault produced the Morgan!