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100-778: The Hayward Fault is parallel to the San Andreas Fault , which lies offshore and through the San Francisco Peninsula . To the east of the Hayward Fault lies the Calaveras Fault . In 2007, the Hayward Fault was discovered to have merged with the Calaveras Fault east of San Jose at a depth of 6.4 kilometers (4.0 mi), with the potential of creating earthquakes much larger than previously anticipated. Some geologists have suggested that

200-426: A decade, owing to various factors. The progressively more severe reports and estimates of event probability and consequences have awakened a broad interest in training people for emergency response. It is becoming widely understood that professional fire fighting, police, and medical services will be overwhelmed by a major event and that neighbors will have to assist each other as best they can. Several jurisdictions in

300-611: A derailment occur. Derailments have often occurred during major earthquakes, both directly by tipping and by roadbed failures; industrial accidents involving these materials have caused extensive health hazards in the mixed residential–industrial areas of Richmond. In addition to extensive modifications to over crossings and elevated structures, largely to prevent dismantling due to shaking or destruction by soil failure, several other unique system feature require special treatment. Transbay tube BART trains travel between San Francisco and Oakland through an underwater tube structure. The tube

400-611: A failure of a single section of the upper deck of the eastern span of the San Francisco–Oakland Bay Bridge , which closed the bridge for 30 days. A replacement of the eastern span was completed in August 2013. Engineers and much of the public had long recognized that a strong earthquake centered close to the bridge on either the Hayward or San Andreas faults could cause a complete collapse of the eastern span. Parallel to

500-476: A large event are likely to be far more severe than seen in the Loma Prieta event. Many modifications have been made to freeway structures to reduce life hazards during seismic events. Significant adverse conditions remain which can cause disruption with possible long-term effects upon critical traffic infrastructure despite these modifications. Warren Freeway portion of Highway 13 In its northern extent,

600-418: A large number of dangerous unreinforced masonry (mostly brick) structures and chimneys, which can be extremely hazardous to occupants in a large earthquake, and a large number of buildings which are either not bolted to their foundations or with soft stories that are insufficiently resistant to shear forces. Foundation and soft story weaknesses are easily remediated in most cases, but this is only effective if

700-560: A link between the water level in Lake Cahuilla (now the Salton Sea ) and seismic activity along the southern San Andreas Fault. The study suggests that major earthquakes along this section of the fault coincided with high water levels in the lake. The hydrological load caused by high water levels can more than double the stress on the southern San Andreas Fault, which is likely sufficient for triggering earthquakes. This may explain

800-418: A liquid mud from the agitation, a mud unable to support buildings erected upon once-firm soil. This region is also covered with dense low-rise urban development, most of which was built soon after the 1906 San Francisco earthquake , and long before even moderately earthquake resistant construction practices had been developed in the late 1920s. Further improvement in the construction of resistant structures and

900-563: A magnitude 7.8 earthquake along the southern San Andreas Fault could cause about 1,800 deaths and $ 213 billion in damage. This scenario hypothesizes the potential effects of a 7.0 magnitude earthquake on the San Andreas Fault in the San Francisco Bay Area. It aims to estimate the impacts on urban infrastructures along with the rebuilding efforts to both the landscape and economy. This study combines not only

1000-644: A major segment can substantially increase the likelihood of an earthquake on an adjacent fault segment, increasing the likelihood of two major regional earthquakes within a period of a few months. The connection between the Rodgers Creek Fault Zone and the Hayward Fault Zone was unclear until 2015 when a survey of the floor of San Pablo Bay found that the ends of the two faults were smoothly linked between Point Pinole and Lower Tubbs Island . An alternate prior hypothesis suggested that

1100-479: A more efficient, equitable, and environmentally sustainable region. ABAG was formed in 1961. In 1970, it issued its Regional Plan, 1970-1990, the Bay Area's first comprehensive regional plan. The document outlined a regional open space plan, regional information systems and technology support, criminal justice and training, water policy and waste collection, and earthquake hazards and planning. ABAG, along with

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1200-662: A possible concurrent scenario (these are shown below). In October 2016, scientists found definitive evidence that the Rodgers Creek Fault and the Hayward Fault are linked together under San Pablo Bay. A simultaneous rupture of the connected Hayward-Rodgers Creek Fault – about 118 mi (190 km) long from just north of Healdsburg down to Alum Rock in San Jose – could result in a major earthquake of magnitude 7.4 that "would cause extensive damage and loss of life with global economic impact". It has been suggested that

1300-587: A possible driver for the deformation of the Basin and Range , separation of the Baja California peninsula , and rotation of the Transverse Range . The main southern section of the San Andreas Fault proper has only existed for about 5 million years. The first known incarnation of the southern part of the fault was Clemens Well-Fenner- San Francisquito fault zone around 22–13 Ma. This system added

1400-647: A road.) Similar conditions underlie the eastern approach roads to the Bay Bridge. Better, but still locally poor soils underlie the portion of Interstate Highway 880 that extends to the South Bay region from the MacArthur Maze . As the bulk of cargo containers from the Port of Oakland travel on these two roads, the disabling of both would cause severe disruption of West Coast import and export goods, owing to

1500-402: A rock overfill. Subsequent seismic analysis indicated the possibility that the overfill could fail due to agitation, allowing the buoyant tube to float upward, misaligning the tracks and possibly overstressing the bolted connections. This potential problem has been addressed by vibratory compaction of the overfill covering the tube. Additional stabilization includes the driving of large pilings and

1600-437: A series of echelon cracks . Creep effects may be seen also in older structures crossing the fault, some of which have been fitted with expansion joints to accommodate this slow motion. The magnitude of an earthquake, as indicated on a seismic scale , is roughly proportional to the length of the rupture, while the ground motion in the region surrounding the fault is highly dependent upon the local soil conditions, somewhat upon

1700-900: Is a regional planning agency incorporating various local governments in the San Francisco Bay Area in California . It encompasses nine counties surrounding the San Francisco Bay. Those counties are Alameda , Contra Costa , Marin , Napa , San Francisco , San Mateo , Santa Clara , Solano , and Sonoma . It has the ability to establish housing and transportation goals for cities to minimize urban sprawl by requiring that housing be zoned for near new workplace construction. It deals with land use, housing, environmental quality, and economic development. Non-profit organizations as well as governmental organizations can be members. All nine counties and 101 cities within

1800-499: Is a combined effort from experts in the physical sciences, social sciences, and engineering both in the public and private sectors- ranging from urban planners to economists/business professionals. Not only does this study aim to estimate the impacts of the event, but aims to estimate the years of rebuilding and funding needed to recover communities from a potential disaster such as the HayWired Scenario. The first volume of

1900-609: Is built on fill placed in the 1930s atop mudflats whose upper layers were deposited in the 19th century as a result of extensive hydraulic gold mining in the distant Sierra Nevada mountain foothills. This soft mud is expected to amplify earthquake shaking, and the mud supporting the heavy fill may liquefy, and so possibly cause major disruption of the highway due to failure by sinking of the highway and by differential movement of large sections. (More modern construction for these conditions employs linked and "floating" – in mud – lightweight concrete and plastic foam box structures to support

2000-406: Is compared to 6.4 percent for the San Andreas Fault, which can have larger earthquakes but is farther away from a significant portion of the urbanized parts of the Bay Area. Earlier (January 2008) assessments suggest that the Hayward, Rodgers Creek, and Calaveras faults may be more likely to fail in the next few decades than previously thought. The 140th anniversary of the 1868 event was in 2008, and

2100-430: Is composed of welded plate steel segments. Each oval outer section carries two inner train tubes of circular cross section and a central rectangular access and rescue tunnel, with the void between elements filled with concrete. The segments were sunk into a ditch dredged through bay mud and covered with rock fill, and then pumped free of water upon completion, making the resulting tube somewhat buoyant, but held in place with

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2200-442: Is considered practical (see below). Seismic sensor network BART has installed and continues to enhance a network of seismic sensors (an earthquake warning system ) to trigger a system halt in the event of a major event, this to include automated event progression analysis to determine the best action with regard to individual trains for maximum safety (a fault rip can take up to several tens of seconds to completely propagate from

2300-614: Is not clear. Several hypotheses have been offered and research is ongoing. One hypothesis – which gained interest following the Landers earthquake in 1992 – suggests the plate boundary may be shifting eastward away from the San Andreas towards Walker Lane. Assuming the plate boundary does not change as hypothesized, projected motion indicates that the landmass west of the San Andreas Fault, including Los Angeles, will eventually slide past San Francisco, then continue northwestward toward

2400-417: Is that experts say there is a 72% chance of experiencing a magnitude 6.7 or greater earthquake before 2045. Moreover, they had a 51% chance of a M≥7 (threshold to be considered a "major" quake), a 20% chance of a M≥7.5 and a 4% chance of a M≥8 (a "great" quake) when all the mapped faults in the region are taken in to account. The surface of the fault is creeping at less than 0.5 cm (0.2 in) per year in

2500-566: Is the approximate location of the epicenter of the 1906 San Francisco earthquake . The fault returns onshore at Bolinas Lagoon just north of Stinson Beach in Marin County . It returns underwater through the linear trough of Tomales Bay which separates the Point Reyes Peninsula from the mainland, runs just east of Bodega Head through Bodega Bay and back underwater, returning onshore at Fort Ross . (In this region around

2600-540: Is the possibility that a large earthquake could trigger very large earth flows, particularly if the soils are seasonally saturated with water, possibly rendering extensive areas unbuildable. (See the Virtual tour – Google Earth Flyover below.) Many structures near the bay shore on either side would probably be severely affected by either a major Hayward Fault rupture or a nearby San Andreas Fault rupture. Severe effects were seen in both Oakland and northern San Francisco from

2700-420: The 1994 Northridge earthquake ) occurs about once every 6.7 years statewide. The same report also estimated there is a 7% probability that an earthquake of magnitude 8.0 or greater will occur in the next 30 years somewhere along the San Andreas Fault. A different USGS study in 2008 tried to assess the physical, social and economic consequences of a major earthquake in southern California. That study predicted that

2800-681: The Aleutian Trench , over a period of perhaps twenty million years. The San Andreas began to form in the mid- Cenozoic about 30 Mya (million years ago). At this time, a spreading center between the Pacific plate and the Farallon plate (which is now mostly subducted, with remnants including the Juan de Fuca plate , Rivera plate , Cocos plate , and the Nazca plate ) was beginning to reach

2900-527: The Caldecott Tunnel , is composed of extensive earth fill at the location where the fault is crossed. An earthquake may cause minor landsliding on some slopes of the freeway, and the plastic movement of the fill would likely disrupt the pavement if the movement here of the surface displacement is substantial, possibly presenting a hazard to motorists and shutting down the highway for a while. More extensive disruption and greater hazard could be caused by

3000-587: The East Pacific Rise to the southeast. It is also being subducted far to the northwest into the Aleutian Trench . In California, the plate is sliding northwestward along a transform boundary , the San Andreas Fault , toward the subduction zone. At the same time, the North American plate is moving southwestward relative to the Earth's core, but southeastward relative to the Pacific plate, due to

3100-625: The Maacama Fault , is also considered to be part of the "Hayward Fault subsystem". While the San Andreas Fault is the principal transform boundary between the Pacific plate and the North American plate , the Hayward-Rodgers Creek Fault takes up its share of the overall displacement of the two plates. The Pacific plate is a major section of the Earth's crust, gradually expanding by the eruption of magma along

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3200-587: The Salton Sea . Here, the plate motion is being reorganized from right-lateral to divergent . In this region (known as the Salton Trough ), the plate boundary has been rifting and pulling apart, creating a new mid-ocean ridge that is an extension of the Gulf of California . Sediment deposited by the Colorado River is preventing the trough from being filled in with sea water from the gulf. The fault

3300-499: The San Francisco Bay Area several significant "sister faults" run more-or-less parallel, and each of these can create significantly destructive earthquakes.) From Fort Ross, the northern segment continues overland, forming in part a linear valley through which the Gualala River flows. It goes back offshore at Point Arena . After that, it runs underwater along the coast until it nears Cape Mendocino , where it begins to bend to

3400-473: The San Gabriel Fault as a primary focus of movement between 10–5 Ma. Currently, it is believed that the modern San Andreas will eventually transfer its motion toward a fault within the eastern California shear zone . This complicated evolution, especially along the southern segment, is mostly caused by either the "Big Bend" and/or a difference in the motion vector between the plates and the trend of

3500-699: The San Gabriel Mountains . These mountains are a result of movement along the San Andreas Fault and are commonly called the Transverse Range. In Palmdale , a portion of the fault is easily examined at a roadcut for the Antelope Valley Freeway . The fault continues northwest alongside the Elizabeth Lake Road to the town of Elizabeth Lake . As it passes the towns of Gorman , Tejon Pass and Frazier Park ,

3600-714: The Santa Cruz Mountains (the location of the Loma Prieta earthquake in 1989). Studies of the relative motions of the Pacific and North American plates have shown that only about 75 percent of the motion can be accounted for in the movements of the San Andreas and its various branch faults. The rest of the motion has been found in an area east of the Sierra Nevada mountains called the Walker Lane or Eastern California Shear Zone. The reason for this

3700-526: The U.S. Geological Survey (USGS) have made variable predictions as to the risk of future seismic events. The ability to predict major earthquakes with sufficient precision to warrant increased precautions has remained elusive. The U.S. Geological Survey's most recent forecast, known as UCERF3 (Uniform California Earthquake Rupture Forecast 3), released in November 2013, estimated that an earthquake of magnitude 6.7 M or greater (i.e. equal to or greater than

3800-736: The Walker Lane east of the Sierra Nevada . 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 complete fault zone, including the Rodgers Creek fault, is divided by seismologists into three segments – Rodgers Creek, Northern Hayward, and Southern Hayward. It is expected that these segments may fail singly or in adjacent pairs, creating earthquakes of varying magnitude. The Association of Bay Area Governments (ABAG) in concert with other government agencies has sponsored

3900-474: The alluvial plain that drops from the East Bay Hills to the eastern shoreline of San Francisco Bay . At the lower elevations near the bay the soil is mostly water saturated mud and sand, placed in the early 20th century as fill in marsh areas. This soil tends to amplify the effects of an earthquake and so producing significantly greater ground motion. Additionally, the soil itself can fail, turning into

4000-480: The 1868 earthquake were to reoccur. Since the fault runs through heavily populated areas, more than 5 million would be affected directly. Water could be cut off to 2.4 million people living in California's San Francisco Bay Area . For the thirty years following 2014, the probability of there being one or more magnitude 6.7+ earthquakes on the Hayward Fault during that time frame was estimated at 14.3 percent. This

4100-458: The 1868 event became known as the "Great San Francisco earthquake" until the larger tremor in 1906. Many seismologists believe that the 1906 San Francisco earthquake , which occurred on the San Andreas fault, reduced the stress on many faults in the Bay Area including the Hayward fault, creating an "earthquake shadow": a quiescent period following a major earthquake. Since the 1906 San Andreas event there have been no moderately strong earthquakes on

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4200-479: The 1989 Loma Prieta earthquake , even though this event was not extremely large and was centered a significant distance away in the Santa Cruz Mountains. Most of the severe effects of that event were due to poorly responding soil conditions and design deficiencies in large structures. Only a portion of the structural deficiencies in the larger area have been addressed, and the surface motion effects of

4300-399: The Bay Area are voluntary members of ABAG. As an advisory organization, ABAG has limited statutory authority. It is governed by its General Assembly, which consists of an elected official (delegate) from each city and county which is a member of the organization. The General Assembly determines policy, adopts the annual budget and work program, and reviews policy actions taken or proposed by

4400-587: The California economy within the first 6 months post-recovery from the event through estimates of "utility outages, property damages, and supply chain disruptions resulting in an estimated $ 44 billion of gross state product (GSP) losses, or translated at 4% of the California economy"(Wein et al.). This study also projects the recovery of jobs lost in highly impacted areas, such as Alameda County, could take up to 10 years to fully recover job losses and possible economic recession. Trajectories for economic recovery are improved by reconstruction but also delayed with impacts to

4500-728: The Eastshore Freeway and inland only two blocks is a four-track railroad route used for general freight traffic, including that generated by the Port of Oakland ( Union Pacific and BNSF railroads) and by Amtrak passenger traffic to the Pacific Northwest and eastward through Reno and Salt Lake City . Along the north shore of Contra Costa County , substantial amounts of pressurized liquid gas, flammable liquids, caustic materials, and various toxics are stored temporarily in bulk railcars adjacent to passenger and freight traffic mainlines, with great potential hazards should

4600-661: The HayWired Scenario study was released in 2017, with consistent continuations and contributions by engineers. This continuation was published in the second volume, Engineering Implications, in 2018. As of the 2021 Fact sheet update, there are several estimates on damages ranging from the approximate people affected at home, work, effects of lifeline infrastructures such as telecommunications, and more. This group of scientists have worked together to create estimates of how hazards such as liquefaction, landslides, and fire ignition will impact access to utilities, transportation, and general emergency services. This study goes into detail about

4700-577: The Hayward Fault and Rodgers Creek Fault were probably connected by a series of en echelon fault strands beneath San Pablo Bay. The new finding means that the Rodgers-Hayward system together could produce a quake with a magnitude as high as 7.2. It is also considered possible that a major seismic event on either fault may involve movement on the other, either concurrently or within an interval of up to several months. The Association of Bay Area Governments has prepared ground shaking maps that include

4800-415: The Hayward Fault in recorded history occurred in 1868, with an estimated magnitude of 7.0. It occurred on the southern segment of the fault, receiving its name (some decades later) from the nascent town of Hayward where it was determined the quake's epicenter was located. However, the 1868 quake caused much damage throughout the then sparsely settled Bay Area, including the city of San Francisco. In fact,

4900-649: The Hayward Fault lies directly beneath the portion of Highway 13 (the Warren Freeway ) that is south of its intersection with Highway 24 and north of its terminal connection with Interstate 580 (the MacArthur Freeway ). In this rift valley there are a number of elevated street crossings in the Montclair District that cross the fault. Highway 24 State Highway 24 , connecting Oakland to Orinda, Lafayette, and Walnut Creek through

5000-600: The Hayward Fault, arguing that it would be cheaper (and less disruptive to current operations) to rebore a misaligned portion after the fact than to protect riders (either by extensive modifications of the tunnel or by replacing it with a higher bore) against the small likelihood that a train (or two) would crash into or be cut in two by a major slippage of the fault. Modified train scheduling to prevent multiple train exposure at faults has been determined by BART engineers to be impractical due to variations in train passage, but automated event-related realtime train operational response

5100-409: The Hayward area may have been greater than in 1906 due to the proximity of the Hayward Fault. Earlier earthquakes have been detected by trench exposure and associated radiocarbon dating . Combined with the historic record, the last five major events were in 1315, 1470, 1630, 1725, and 1868, which have intervals of about 140 years (note that 2018 is 150 years from the major 1868 event). The longest time

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5200-540: The Hayward fault as were seen before that earthquake. It also appears likely that this quiet period in the earthquake shadow is ending, as projected by the rate of plate motion and the stress state of other faults in the region. The 1868 earthquake occurred well before the East Bay region was extensively urbanized. The following year, in 1869, the William Meek Estate became one of the first developments in

5300-463: The San Andreas fault has reached a sufficient stress level for an earthquake of magnitude greater than 7.0 on the moment magnitude scale to occur. This study also found that the risk of a large earthquake may be increasing more rapidly than scientists had previously believed. Moreover, the risk is currently concentrated on the southern section of the fault, i.e. the region around Los Angeles, because strong earthquakes have occurred relatively recently on

5400-450: The San Andreas. As with portions of other faults, a large extent of the Hayward Fault trace is formed from a narrow complex zone of deformation which can span hundreds of feet in width. The transform boundary defined by the San Andreas Fault is not perfectly straight, and the stresses between the Pacific and North American plates are diffused over a wide region of the West, extending as far as

5500-542: The Southern Calaveras should be renamed as the Southern Hayward. North of San Pablo Bay is the Rodgers Creek Fault, which was shown in 2016 to be linked with the Hayward Fault under San Pablo Bay to form a combined Hayward-Rodgers Creek Fault that is 190 kilometers (120 mi) long, stretching from north of Healdsburg through Santa Rosa down to Alum Rock in San Jose. Another fault further north,

5600-455: The U.S. state of California . It forms part of the tectonic boundary between the Pacific plate and the North American plate . Traditionally, for scientific purposes, the fault has been classified into three main segments (northern, central, and southern), each with different characteristics and a different degree of earthquake risk. The average slip rate along the entire fault ranges from 20 to 35 mm (0.79 to 1.38 in) per year. In

5700-578: The abnormally long period of time since the last major earthquake in the region since the lake has dried up. The San Andreas Fault System has been the subject of a flood of studies. In particular, scientific research performed during the last 23 years has given rise to about 3,400 publications. A study published in 2006 in the journal Nature by Yuri Fialko, an associate professor at the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics at Scripps Institution of Oceanography , found that

5800-577: The affected area have implemented volunteer Community emergency response team programs to augment the professional response services. In 2012, USGS scientists said the fault was due for another magnitude 6.8 to 7.0 earthquake, with the California Geological Survey concurring, stating they believe there is a 31 percent chance of a magnitude-6.7 earthquake or greater along the Rodgers Creek-Hayward Fault in

5900-461: The analysis of local conditions and the preparation of maps indicative of the destructive potential of these earthquakes. The various ABAG maps shown below represent some of the more likely possible combinations. While there are indications that a substantial earthquake on a nearby parallel fault can release stress and so also decrease the near-term probability of an earthquake, the opposite appears to be true concerning sequential segments. A release on

6000-543: The area, built on 3,000 acres (12 km) in what became known as the Cherryland district of Eden Township. Recent renovations of the Meek Mansion have revealed that with the 1868 earthquake still fresh in minds of residents of the time, some unusual diagonal bracing was built into the original construction. Although its magnitude was less than the 1906 San Francisco earthquake, the intensity of shaking experienced in

6100-487: The average time between the last five major events is also averaged at 140 years. Recent estimates of the damage potential of a major Hayward Fault earthquake by a professional risk management firm indicate the potential for huge economic losses, of which only a small percentage is insured against earth movement. (Earthquake insurance is not only quite expensive, it tends to be burdened with large deductibles – at least 15 percent). Depending upon seasonal weather conditions at

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6200-1194: The central ( 1857 ) and northern ( 1906 ) segments of the fault, while the southern section has not seen any similar rupture for at least 300 years. According to this study, a major earthquake on that southern section of the San Andreas fault would result in major damage to the Palm Springs – Indio metropolitan area and other cities in San Bernardino , Riverside and Imperial counties in California, and Mexicali Municipality in Baja California . It would be strongly felt (and potentially cause significant damage) throughout much of Southern California , including densely populated areas of Los Angeles County , Ventura County , Orange County , San Diego County , Ensenada Municipality and Tijuana Municipality , Baja California, San Luis Rio Colorado in Sonora and Yuma, Arizona . Older buildings would be especially prone to damage or collapse, as would buildings built on unconsolidated gravel or in coastal areas where water tables are high (and thus subject to soil liquefaction ). Of

6300-598: The connection of additional restraints. Slip joint The transbay tube terminates at an under-bay slip joint near the Embarcadero Station in San Francisco. The designed slip margin has been reduced by half due to unforeseen settlement of the tube structure. The projected worst-case motion at this joint has been determined to be beyond that for which the joint is presently capable, which could cause severe structural problems and mud and water entry into

6400-637: The consequent overloading of other West Coast container handling ports. Highway 580 A major route for commuters traveling from Southern Alameda County, the San Joaquin Valley and the East Bay hills to downtown Oakland and San Francisco, Interstate 580 crosses the fault, and runs very close to the fault between the intersections with State Route 13 (the Warren Freeway) and Interstate 238 . The 1989 Loma Prieta earthquake caused

6500-523: The construction industry. A 2008 paper, studying past earthquakes along the Pacific coastal zone, found a correlation in time between seismic events on the northern San Andreas Fault and the southern part of the Cascadia subduction zone (which stretches from Vancouver Island to Northern California). Scientists believe quakes on the Cascadia subduction zone may have triggered most of the major quakes on

6600-553: The development of retrofitting method have only recently been developed, largely in response to the effects of the 1971 Sylmar , 1989 Loma Prieta , and 1994 Northridge events in California – none of which were hugely catastrophic, but each of which caused loss of life in structures not thought to be vulnerable, and so increased public, engineering, and government awareness of the need for specific remediations and construction methods required for improved life safety. Although many structures have undergone seismic retrofitting there are

6700-424: The distance and relationship to the progression of the fault rupture, and (as recently recognized in the 1989 Loma Prieta earthquake ) reflected energy from deep discontinuities in the Earth's structure. The area affected by an earthquake is also dependent upon the density and uniformity of the soils surrounding the fault. The Hayward fault is considered to be particularly dangerous due to the poor soil conditions in

6800-665: The eastern side of the fault. The effect is expressed as the Coast Ranges. The northwest movement of the Pacific plate is also creating significant compressional forces which are especially pronounced where the North American plate has forced the San Andreas to jog westward. This has led to the formation of the Transverse Ranges in Southern California, and to a lesser but still significant extent,

6900-591: The epicenter to the more distant affected locations). Such sensor networks and warning devices have a potential to reduce the hazards from falling objects and furnishings provided that the people notified are well trained in appropriate responses (similar to the Cold War's " duck and cover " training of schoolchildren). Of primary concern with respect to the Hayward Fault is the huge Chevron Richmond Refinery in Richmond . Although founded on better ground than most of

7000-538: The failure of elevated structures, both those over which the highway passes and overcrossings of the freeway, of which there are two nearby. As elsewhere in the area, such structures have undergone extensive retrofitting for safety. Highways 80 and 880 and the Port of Oakland A severe earthquake is likely to disable the offshore causeway portions of Interstate Highway 80 (the Eastshore Freeway ), since it

7100-515: The fault and its surrounding branches. The fault was first identified in Northern California by UC Berkeley geology professor Andrew Lawson in 1895 and named by him after the surrounding San Andreas valley. Eleven years later, Lawson discovered that the San Andreas Fault stretched southward into southern California after reviewing the effects of the 1906 San Francisco earthquake . Large-scale (hundreds of miles) lateral movement along

7200-560: The fault begins to bend northward, forming the "Big Bend". This restraining bend is thought to be where the fault locks up in Southern California , with an earthquake-recurrence interval of roughly 140–160 years. Northwest of Frazier Park, the fault runs through the Carrizo Plain , a long, treeless plain where much of the fault is plainly visible. The Elkhorn Scarp defines the fault trace along much of its length within

7300-465: The fault from 2004 to 2007. The aim was to collect core samples and make direct geophysical and geochemical observations to better understand fault behavior at depth. The northern segment of the fault runs from Hollister , through the Santa Cruz Mountains , epicenter of the 1989 Loma Prieta earthquake , then up the San Francisco Peninsula , where it was first identified by Professor Lawson in 1895, then offshore at Daly City near Mussel Rock . This

7400-452: The fault he previously discovered. He concluded that the fault must have been the origin of the earthquake. This line ran through San Andreas Lake , a sag pond . The lake was created from an extensional step over in the fault, which created a natural depression where water could settle. A common misconception is that Lawson named the fault after this lake. However, according to some of his reports from 1895 and 1908, he actually named it after

7500-632: The fault was first proposed in a 1953 paper by geologists Mason Hill and Thomas Dibblee . This idea, which was considered radical at the time, has since been vindicated by modern plate tectonics . Seismologists discovered that the San Andreas Fault near Parkfield in central California consistently produces a magnitude 6.0 earthquake approximately once every 22 years. Following recorded seismic events in 1857, 1881, 1901, 1922, 1934, and 1966, scientists predicted that another earthquake should occur in Parkfield in 1993. It eventually occurred in 2004 . Due to

7600-557: The frequency of predictable activity, Parkfield has become one of the most important areas in the world for large earthquake research. In 2004, work began just north of Parkfield on the San Andreas Fault Observatory at Depth (SAFOD). The goal of SAFOD is to drill a hole nearly 3 kilometres (1.9 mi) into the Earth's crust and into the San Andreas Fault. An array of sensors will be installed to record earthquakes that happen near this area. A 2023 study found

7700-433: The geological impacts/effects of the event, but also the societal impacts such as property damage, economic rebuilding, and aims at estimating damages if cities increased risk-reduction. It was developed for preparedness geared towards Bay Area residents and as a warning with an attempt to encourage local policy makers to create infrastructure and protections that would further risk reduction and resilience-building. This study

7800-600: The latter's much faster northwestward motion. The westward component of the North American plate's motion results in some compressive force along the San Andreas and its associated faults, thus helping lift the Pacific Coast Ranges and other parallel inland ranges to the west of the Central Valley , in this region most notably the Diablo Range . The Hayward Fault shares the same relative motions of

7900-511: The name "Rodgers Creek Fault" be retired and that the entire 118 mi (190 km) fault be known as the "Hayward Fault". The Calaveras Fault is continuous from the Sunol area south to Hollister . 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

8000-510: The next 30 years. In March 2015, the United States Geological Survey released "UCERF3: A New Earthquake Forecast for California's Complex Fault System". The UCERF3 represents the best available science to date, and it now considers "multifault ruptures" and "fault readiness", in addition to historical seismicity, in the calculus of earthquake forecasting. The upshot, for those who live in the San Francisco Bay Area,

8100-561: The north, the fault terminates offshore near Eureka, California , at the Mendocino triple junction , where three tectonic plates meet. The Cascadia subduction zone intersects the San Andreas fault at the Mendocino triple junction. It has been hypothesized that a major earthquake along the Cascadia subduction zone could trigger a rupture along the San Andreas Fault. In the south, the fault terminates near Bombay Beach, California , in

8200-557: The northern San Andreas within the past 3,000 years. The evidence also shows the rupture direction going from north to south in each of these time-correlated events. However the 1906 San Francisco earthquake seems to have been the exception to this correlation because the plate movement was mostly from south to north and it was not preceded by a major quake in the Cascadia zone. The San Andreas Fault has had some notable earthquakes in historic times: Association of Bay Area Governments The Association of Bay Area Governments ( ABAG )

8300-935: The organization's Executive Board. A majority of city and county votes are required for action. The organization is associated with such agencies and projects as the San Francisco Bay Trail and the San Francisco Estuary Partnership . ABAG works with other regional agencies, including the Metropolitan Transportation Commission (MTC) , Bay Area Air Quality Management District , and San Francisco Bay Conservation and Development Commission , to promote sustainable development by working in partnership with city and county governments to establish both Priority Development Areas and Priority Conservation Areas. These local actions will, in turn, help achieve

8400-609: The plain. The southern segment, which stretches from Parkfield in Monterey County all the way to the Salton Sea , is capable of an 8.1-magnitude earthquake. At its closest, this fault passes about 35 miles (56 km) to the northeast of Los Angeles. Such a large earthquake on this southern segment would kill thousands of people in Los Angeles, San Bernardino, Riverside, and surrounding areas, and cause hundreds of billions of dollars in damage. The Pacific plate , to

8500-464: The regions of concern. Extreme southern regions of the fault are creeping more quickly, perhaps sufficiently to prevent fault rupture there, but mostly the creep is insufficient to relieve the accumulating forces upon most of the fault and so will not prevent a large earthquake. The creep is sufficient to displace roads, curbs, and sidewalks and so visibly reveal the surface trace in many locations. Creep damage to asphalt road surfaces will usually appear as

8600-420: The shoreline, this refinery has extensive crude oil and finished product docks and pipelines extending into the bay, which could produce catastrophic spills into the bay, with the potential to adversely affect hundreds of miles of sensitive wetlands. Dismantling of high pressure and temperature process units and the consequent fire danger to personnel and equipment could produce substantial economic consequences for

8700-526: The specific populations to be hardest impacted by a potential earthquake of a 7.0 magnitude, specifically in the San Francisco Bay Area. This includes intensified hardships for those with low-income, racially and culturally-diverse populations, and people with literacy hardships that would significantly "increase their risk of displacement and add to recovery challenges" (Wein et al.). In addition to societal and landscape impacts, this study looks at potential business interruptions. This portion estimates impacts to

8800-412: The study, Fialko stated: All these data suggest that the fault is ready for the next big earthquake but exactly when the triggering will happen and when the earthquake will occur we cannot tell. It could be tomorrow or it could be 10 years or more from now. Nevertheless, in the 18 years since that publication there has not been a substantial quake in the Los Angeles area, and two major reports issued by

8900-500: The subduction zone off the western coast of North America. As the relative motion between the Pacific and North American plates was different from the relative motion between the Farallon and North American plates, the spreading ridge began to be "subducted", creating a new relative motion and a new style of deformation along the plate boundaries. These geological features are what are chiefly seen along San Andreas Fault. It also includes

9000-450: The surrounding San Andreas Valley. Following the 1906 San Francisco earthquake, Lawson also concluded that the fault extended all the way into Southern California . In 1953, geologist Thomas Dibblee concluded that hundreds of miles of lateral movement could occur along the fault. A National Science Foundation funded project called the San Andreas Fault Observatory at Depth (SAFOD) near Parkfield, California , involved drilling through

9100-419: The time of a major event a seismic event could be followed by urban wildfires compounded by damage to water systems or massive landslides in saturated soils. In addition to direct damage the effects on commerce due to damaged infrastructure would also be substantial. Experience with large area urban destruction such as caused by earthquake, hurricane, and firestorms has shown that complete rebuilding can take up to

9200-477: The tube and adjacent subway systems. This is to be corrected at great expense – first estimated at $ 142 million but expected to cost far more – probably the largest single cost item in the list of BART seismic retrofits. Berkeley Hills Tunnel In June 2006 Bay Area Rapid Transit (BART) management announced that they have elected not to modify the Berkeley Hills Tunnel , which actually penetrates

9300-419: The two may be connected. If true, this link would have significant implications for the potential maximum strength of earthquakes on the Hayward, since this strength is determined by the maximum length of the fault rupture and this rupture could extend beyond the juncture point and so include some portion of the Calaveras. (This potential is not shown in the shake intensity maps shown below.) The largest quake on

9400-420: The west of the fault, is moving in a northwest direction while the North American plate to the east is moving toward the southwest, but relatively southeast under the influence of plate tectonics . The rate of slippage averages about 33 to 37 millimeters (1.3 to 1.5 in) a year across California. The southwestward motion of the North American plate towards the Pacific is creating compressional forces along

9500-423: The west, terminating at the Mendocino triple junction . The central segment of the San Andreas Fault runs in a northwestern direction from Parkfield to Hollister . While the southern section of the fault and the parts through Parkfield experience earthquakes, the rest of the central section of the fault exhibits a phenomenon called aseismic creep , where the fault slips continuously without causing earthquakes. It

9600-502: The western states. Large liquid storage tanks are protected by berms that are designed to contain the contents should a tank fail under normal conditions. Similar process and product conditions exist at other refineries further inland near Martinez , but mostly these plants are exposed to earthquakes from other faults. San Andreas Fault The San Andreas Fault is a continental right-lateral strike-slip transform fault that extends roughly 1,200 kilometers (750 mi) through

9700-486: The work is competently done, with proper attention to minor details such as nailing patterns and proper connections. Local surveys of recently completed work have exposed deficient workmanship in a number of cases involving household retrofits. There are many small active landslides and evidence of numerous large archaic landslides in the Berkeley Hills . Such areas may be stable only under present conditions. There

9800-425: Was first identified in 1895 by Professor Andrew Lawson of UC Berkeley . In the wake of the 1906 San Francisco earthquake , Lawson was tasked with deciphering the origin of the earthquake. He began by surveying and mapping offsets (such as fences or roads that had been sliced in half) along surface ruptures. When the location of these offsets were plotted on a map, he noted that they made a near perfect line on top of

9900-528: Was formed by a transform boundary. The southern segment (also known as the Mojave segment) begins near Bombay Beach, California . Box Canyon, near the Salton Sea , contains upturned strata associated with that section of the fault. The fault then runs along the southern base of the San Bernardino Mountains , crosses through Cajon Pass and continues northwest along the northern base of

10000-467: Was the 160-year period between 1470 and 1630. In 2028, it will have been 160 years since the 1868 event. United States Geological Survey (USGS) scientists state that a major earthquake occurring on the zone is "increasingly likely". When the next major earthquake occurs on the fault, damage will be catastrophic. More than 1.5 trillion U.S. dollars in property exists in the affected area, and more than 165 billion US dollars in damage would likely result if

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