Hayward Fault Zone - AbsoluteAstronomy.com

The Hayward Fault Zone is a geologic fault

Geologic fault

In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...

zone capable of generating significantly destructive earthquake

Earthquake

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

s. This strike-slip fault

Strike-slip tectonics

Strike-slip tectonics is concerned with the structures formed by, and the tectonic processes associated with, zones of lateral displacement within the crust or lithosphere.-Deformation styles:-Riedel shear structures:...

is about 74 mi (119.1 km) long, situated mainly along the western base of the hills on the east side of San Francisco Bay

San Francisco Bay

San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...

. It runs through densely-populated areas, including the cities of Richmond

Richmond, California

Richmond is a city in western Contra Costa County, California, United States. The city was incorporated on August 7, 1905. It is located in the East Bay, part of the San Francisco Bay Area. It is a residential inner suburb of San Francisco, as well as the site of heavy industry, which has been...

, El Cerrito

El Cerrito, Contra Costa County, California

-Transportation:The city's primary transportation infrastructure consists of the El Cerrito Plaza and El Cerrito del Norte BART stations along with several local bus lines, operated by AC Transit, providing access to the surrounding area and the nearby cities of Albany, Berkeley and Richmond...

, Berkeley

Berkeley, California

Berkeley is a city on the east shore of the San Francisco Bay in Northern California, United States. Its neighbors to the south are the cities of Oakland and Emeryville. To the north is the city of Albany and the unincorporated community of Kensington...

, Oakland

Oakland, California

Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...

, San Leandro

San Leandro, California

San Leandro is a city in Alameda County, California, United States. It is considered a suburb of Oakland and San Francisco. The population was 84,950 as of 2010 census. The climate of the city is mild throughout the year.-Geography and water resources:...

, Hayward

Hayward, California

Hayward is a city located in the East Bay in Alameda County, California. With a population of 144,186, Hayward is the sixth largest city in the San Francisco Bay Area and the third largest in Alameda County. Hayward was ranked as the 37th most populous municipality in California. It is included in...

, Fremont

Fremont, California

Fremont is a city in Alameda County, California. It was incorporated on January 23, 1956, from the merger of five smaller communities: Centerville, Niles, Irvington, Mission San Jose, and Warm Springs...

, and San Jose

San Jose, California

San Jose is the third-largest city in California, the tenth-largest in the U.S., and the county seat of Santa Clara County which is located at the southern end of San Francisco Bay...

.

The Hayward Fault is parallel to its more famous (and much longer) westerly neighbor, the San Andreas Fault

San Andreas Fault

The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...

, which lies offshore and through the San Francisco peninsula. To the east of the Hayward lies the Calaveras Fault

Calaveras Fault

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...

. The Hayward Fault merges with the Calaveras Fault east of San Jose.

North of San Pablo Bay

San Pablo Bay

San Pablo Bay is a tidal estuary that forms the northern extension of San Francisco Bay in northern California in the United States. Most of the Bay is shallow; however, there is a deep water channel approximately in mid bay, which allows access to Sacramento, Stockton, Benicia, Martinez, and...

, and somewhat offset from the Hayward Fault is the Rodgers Creek Fault, considered by many to be an extension of the Hayward Fault Zone. Another fault further north, the Maacama Fault

Maacama Fault

The Maacama Fault is a right lateral-moving geologic fault located in the Coast Ranges of northwestern California. It is considered to be the northernmost segment of the Hayward Fault subsystem of the San Andreas Fault zone. Creep along the Maacama is about 8 mm per year, consistent with the...

, is also considered to be part of the "Hayward Fault subsystem".

While the San Andreas Fault is the principal transform boundary

Transform fault

A transform fault or transform boundary, also known as conservative plate boundary since these faults neither create nor destroy lithosphere, is a type of fault whose relative motion is predominantly horizontal in either sinistral or dextral direction. Furthermore, transform faults end abruptly...

between the Pacific Plate

Pacific Plate

The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....

and the North American Plate

North American Plate

The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...

, the Hayward Fault takes up a share of the overall motion between the plates.

Tectonics of the Hayward Fault Zone

Main articles: Seafloor spreading
Seafloor spreading
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics....

, Subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

, Plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

, Geologic fault
Geologic fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...

, Earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

The Pacific Plate

Pacific Plate

The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....

is a major section of the Earth's crust, gradually expanding

Seafloor spreading

Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics....

by the eruption of magma

Magma

Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...

along the East Pacific Rise

East Pacific Rise

The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate...

to the southeast. It is also being subducted far to the northwest into the Aleutian Trench

Aleutian Trench

The Aleutian Trench is a subduction zone and oceanic trench which runs along the southern coastline of Alaska and the adjacent waters of northeastern Siberia off the coast of Kamchatka Peninsula. It is classified as a "marginal trench" in the east as it runs along the margin of the continent, and...

and also in a northerly direction under the North American Plate at the Cascadia Fault

Cascadia subduction zone

The Cascadia subduction zone is a subduction zone, a type of convergent plate boundary that stretches from northern Vancouver Island to northern California. It is a very long sloping fault that separates the Juan de Fuca and North America plates.New ocean floor is being created offshore of...

, well north of San Francisco at the terminus of the San Andreas. In California, the plate is sliding northwestward along a transform boundary, the San Andreas Fault

San Andreas Fault

The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...

, toward the subduction zone. At the same time, the North American Plate

North American Plate

is moving southwestward, but relatively southeast along the fault. 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

Pacific Coast Ranges

The Pacific Coast Ranges and the Pacific Mountain System are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico...

and other parallel inland ranges to the west of the Central Valley, in this region most notably the Diablo Range

Diablo Range

The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges. It is located in the eastern San Francisco Bay area south to the Salinas Valley area of northern California, the United States.-Geography:...

. The Hayward Fault shares the same relative motions of 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.

As the transform boundary defined by the San Andreas Fault is not perfectly straight, and the motion of the North American plate

North American Plate

is not entirely parallel to the plate boundary, movement along the boundary creates stresses in the crust on either side of the boundary, resulting in additional faulting on both sides of the San Andreas Fault. The Hayward Fault is one of the larger faults created this way, along with the Calaveras Fault

Calaveras Fault

to the east and the San Gregorio Fault

San Gregorio Fault

The San Gregorio Fault is an active earthquake fault located off the coast of Northern California. The southern end of the fault is in southern Monterey Bay, and the northern end is about 20 km northwest of San Francisco, near Bolinas Bay, where the San Gregorio intersects the San Andreas Fault...

, west of the San Andreas.

Rodgers Creek Fault Zone

The Rodgers Creek Fault Zone is considered by many experts to be an extension of the Hayward Fault Zone. However, the connection between the two faults is still unclear as they are not aligned under San Pablo Bay. In fact, the Rodgers Creek Fault is actually aligned with the Pinole Valley Fault, not the Hayward Fault. Nonetheless, the current view is that the "Hayward Fault" and Rodgers Creek Fault are probably connected by a series of en echelon fault strands beneath San Pablo Bay. It is 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

Association of Bay Area Governments

The Association of Bay Area Governments is a regional planning agency incorporating various local governments in the San Francisco Bay Area in California. It deals with land use, housing, environmental quality, and economic development. Non-profit organizations as well as governmental...

has prepared ground shaking maps that include a possible concurrent scenario (these are shown below).

Calaveras Fault

The Calaveras Fault

Calaveras Fault

is considered to be continuous from the Danville

Danville, California

The Town of Danville is located in the San Ramon Valley in Contra Costa County, California. It is one of the incorporated municipalities in California that uses "town" in its name instead of "city". The population was 42,039 in 2010. Danville is one of the wealthiest suburbs of Oakland and San...

area south to Hollister

Hollister, California

Hollister is a city in and the county seat of San Benito County, California, United States. The population was 34,928 at the 2010 census. Hollister is primarily an agricultural town.-History:...

. It was long believed that there was no connection between the Hayward Fault and the Calaveras. Recent geological studies (particularly the examination of very small and deep earthquakes) suggest that the two faults may be connected. If true, this 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.)

Notable earthquakes

The largest quake on the Hayward Fault in recorded history occurred in 1868, with an estimated magnitude

Moment magnitude scale

The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

of 7.0. It occurred on the southern segment of the fault, receiving its name (some decades later) from the nascent town of Hayward

Hayward, California

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, the 1868 quake became known as the "Great San Francisco Earthquake" until the larger tremor in 1906.

The last truly major earthquake in the region was the 1906 San Francisco Earthquake

1906 San Francisco earthquake

The San Francisco earthquake of 1906 was a major earthquake that struck San Francisco, California, and the coast of Northern California at 5:12 a.m. on Wednesday, April 18, 1906. The most widely accepted estimate for the magnitude of the earthquake is a moment magnitude of 7.9; however, other...

which occurred on the San Andreas fault. Many seismologists believe that the 1906 earthquake 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 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 following table chronologically lists all of the historic earthquakes on the Hayward Fault Zone which have exceeded magnitude 5.5.


Year	City	Date	Magnitude	Epicenter and notes
1864	South Hayward area	May 21, 1864	5.8	Epicenter coordinates:37.6,-121.9
1868 1868 Hayward earthquake The 1868 Hayward earthquake was the last large earthquake to occur on the Hayward Fault Zone in the San Francisco Bay Area, California, United States. It caused significant damage throughout the region, and was known as the "Great San Francisco Earthquake" prior to the 1906 San Francisco earthquake...	Hayward	October 21, 1868	6.8 to 7.0	Epicenter coordinates:37.7,-122.10 This event left 30 dead, and $350,000 in property damage.
1870	Berkeley	April 2, 1870	5.8	Epicenter coordinates:37.9,-122.3
1889	Alameda County (now east Oakland area)	July 31, 1889	5.6	Epicenter coordinates:37.8,-122.2

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 the area, built on 3,000 acres (12 km²) 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

1906 San Francisco earthquake

, the intensity of shaking experienced in the Hayward area may have been greater than in 1906 due to the proximity of the Hayward Fault.

Prehistoric earthquakes

Earlier earthquakes have been detected by trench exposure and associated carbon 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 2008 is 140 years from the major 1868 event).

Recent activity

During 2007, a number of small earthquakes occurred on the northern segment of the Hayward Fault from Oakland to Berkeley.

On October 30, 2007 at 20:04 Pacific time, a magnitude 5.6 earthquake

2007 Alum Rock earthquake

The 2007 Alum Rock earthquake occurred on October 30, 2007 at approximately 8:04 p.m. PDT in Alum Rock Park in San Jose, California...

struck the adjacent Calaveras Fault

Calaveras Fault

in Alum Rock Park

Alum Rock Park

Alum Rock Park, founded in 1872, was the first municipal park in the U.S. state of California. Located in a valley in the Diablo Range foothills on the east side of San Jose, the 720 acre park offers 13 miles of trails, varying from fairly level along Penitencia Creek to sharp switchbacks...

near San Jose

San Jose, California

San Jose is the third-largest city in California, the tenth-largest in the U.S., and the county seat of Santa Clara County which is located at the southern end of San Francisco Bay...

, close to where the Hayward Fault diverges from it. The effects of an earthquake of this size include the spilling of merchandise from store shelves but little structural damage. An earthquake of this size can be locally terrifying and this particular event was also widely felt throughout Northern California and as far north as Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

owing to the time of day, when most people were awake and sitting quietly in their homes. Minor aftershocks continued through Spring 2008.

Between late August and late September 2011, a string of small earthquakes ranging from magnitude 3.6 to 3.2 centered in southeast Oakland near the Oakland Zoo

Oakland Zoo

Oakland Zoo, in the past known as the Knowland Zoo, is a zoo located in southeastern Oakland, California, United States. Oakland Zoo is relatively small for a city of its size, but it contains modern exhibits. Most of its animals are kept in relatively "natural" habitats, and expanded natural...

occurred with the majority of the shaking felt in San Leandro.

Over October and November 2011, a string of earthquakes ranging from magnitude 3.0 to 4.0 occurred on the Hayward Fault, centered near the UC-Berkeley campus. A magnitude 4.0 earthquake occurred on the Hayward Fault on October 20, 2011 at 14:41. This earthquake was centered in southeast Berkeley with an epicenter close to Memorial Stadium. This was followed by less energetic but deeper and more strongly felt 3.8 event at 20:16, with an epicenter 0.9 mile (1.5 km) further south. Owing to the depths of the epicenters these moderate quakes were felt over a wide region, including the nine Bay Area counties. One week later, a magnitude 3.6 earthquake occurred near to Berkeley on October 27, 2011; however, since this happened at 05:36 in the early morning it was less widely observed. On November 5, 2011, a magnitude 3.1 earthquake occurred, centered in Piedmont.

In September 2003, an earthquake of similar magnitude to those of October 2011 occurred near Piedmont, close to Berkeley.

Probability of future activity

United States Geological Survey

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

(USGS) scientists state that a major earthquake occurring on the zone is "increasingly likely". If a major earthquake were to occur on the fault, damage would be catastrophic. More than 1.5 trillion U.S. dollars

United States dollar

The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

in property exists in the affected area, and more than 165 billion US dollars in damage would likely result if the 1868 quake were to recur. Since the fault runs through heavily populated areas, more than 5 million would be affected directly. The Eastern Span of the Bay Bridge would probably be destroyed (unless its replacement span had been completed by that time), cutting off easy transportation between San Francisco and Oakland along with up to 1,100 other roads. Water could be cut off to 2.4 million people living in California's San Francisco Bay Area

San Francisco Bay Area

The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...

.

The probability of a major earthquake on the Hayward within the next thirty years was estimated at nearly 30 percent, compared to about 20 percent for the San Andreas Fault, which can have larger earthquakes but farther away from a significant portion of the urbanized parts of the Bay Area. Recent (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 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

Risk management

Risk management is the identification, assessment, and prioritization of risks followed by coordinated and economical application of resources to minimize, monitor, and control the probability and/or impact of unfortunate events or to maximize the realization of opportunities...

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 huge deductibles - at least 15 percent). Depending upon seasonal weather conditions at the time of a major event a seismic event could be followed by huge 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 a decade, owing to various factors including disputes with insurance companies, a lack of qualified local builders, shortages of supplies, and an influx of contractors from outside of the region of dubious qualifications with no incentive to maintain and enhance a local reputation.

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.

Principal segments

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

Association of Bay Area Governments

(ABAG) in concert with other government agencies has sponsored 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 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.

Fault effects

Fault creep

The surface of the fault is creeping at less than 0.5 cm (0.2 in) per year in 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 a series of echelon

Echelon

Echelon may refer to:* A level or rank in an organization, profession, or society.* Echelon formation, a military hierarchical formation, also used to describe the migratory patterns of birds...

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.

Earthquake shaking

The magnitude of an earthquake, as measured by the moment magnitude scale

Moment magnitude scale

(or for small events the more commonly known Richter magnitude scale

Richter magnitude scale

The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake....

) is roughly proportional to the length of the rupture, while the ground motion in a large region surrounding the fault is highly dependent upon the local soil conditions, somewhat upon the distance and relationship to the progression of the fault rupture and (as recently recognized in the Loma Prieta earthquake

Loma Prieta earthquake

The Loma Prieta earthquake, also known as the Quake of '89 and the World Series Earthquake, was a major earthquake that struck the San Francisco Bay Area of California on October 17, 1989, at 5:04 p.m. local time...

) 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.

Shaking intensity maps for various Hayward and Rodgers Creek Fault earthquake scenarios, from ABAG Quake website

*Recent examination of damage reports from the 1868 event suggest that the rupture over only portions of the Northern and Southern Hayward fault could generate a magnitude 7.0 event, far more powerful than either the 6.5 event shown here or the 6.7 previously recognized as a likely maximum.

The terms used by ABAG for shaking intensity differ from the official descriptions of the Mercalli intensity scale

Mercalli intensity scale

The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude M_w usually reported for an earthquake , which is a measure of the energy released...

, being somewhat softened (perhaps due to the extensive local experience with earthquakes), with terms such as "Rather Strong" becoming "Light", and "Ruinous" and "Disastrous" becoming variations of "Violent".

Bayside soil conditions

Main articles: Bay mud

Bay mud

Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles...

, Soil liquefaction

Soil liquefaction

Soil liquefaction describes a phenomenon whereby a saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid....

, earthquake liquefaction

The Hayward fault is considered to be particularly dangerous due to the poor soil conditions in the alluvial plain

Alluvial plain

An alluvial plain is a relatively flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms...

that drops from the East Bay Hills to the eastern shoreline of San Francisco Bay

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 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

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 the development of retrofitting method have only recently been developed, largely in response to the effects of the 1971 Sylmar

Sylmar earthquake

The 1971 San Fernando earthquake struck the San Fernando Valley near Sylmar, California at 6:00:55 a.m. PST on February 9, 1971, with a magnitude of 6.6....

, 1989 Loma Prieta

Loma Prieta earthquake

, and 1994 Northridge

Northridge earthquake

The Northridge earthquake was a massive earthquake that occurred on January 17, 1994, at 04:31 Pacific Standard Time in Reseda, a neighborhood in the city of Los Angeles, California, lasting for about 10–20 seconds...

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 retrofit

Seismic retrofit

Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with our recent experiences with large earthquakes near urban centers,...

ting there are a large number of dangerous un-reinforced masonry

Masonry

Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, travertine, limestone; concrete block, glass block, stucco, and...

(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 which are elevated upon partial stories that are insufficiently resistant to shear forces. Foundation and partial story weaknesses are easily remediated in most cases, but this is only effective if 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. For the recommendations of a public agency for simple low-rise construction see this City of San Leandro site

Ancient and prehistoric massive landslides and modern instabilities

There are many small active landslides and evidence of numerous large archaic landslides in the Berkeley Hills

Berkeley Hills

The Berkeley Hills are a range of the Pacific Coast Ranges that overlook the northeast side of the valley that surrounds San Francisco Bay. They were previously called the "Contra Costa Range/Hills" , but with the establishment of Berkeley and the University of California, the current usage was...

. Such areas may be stable only under present conditions. There 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.)

Potentially impacted structures and features

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 the 1989 Loma Prieta earthquake

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 a large event are likely to be far more severe than seen in the Loma Prieta event.

Freeways and overcrossings

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, the Hayward Fault lies directly beneath the portion of Highway 13 (the Warren Freeway) that is south of its intersection Highway 24

California State Route 24

State Route 24 in the U.S. state of California is a heavily-traveled east–west freeway in the eastern side of the San Francisco Bay Area of northern California that runs from the Interstate 580/Interstate 980 interchange in Oakland to the Interstate 680 junction in Walnut Creek...

and north of its terminal connection with Interstate 580

Interstate 580 (California)

Interstate 580 is an 80-mile east–west Interstate Highway in Northern California. The heavily traveled spur route of Interstate 80 runs from San Rafael in the San Francisco Bay Area to Interstate 5 near Tracy in the Central Valley...

(the MacArthur Freeway). In this rift

Rift

In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....

valley there are a number of elevated street crossings in the Montclair District

Montclair, Oakland, California

Montclair is a neighborhood of Oakland, California. Montclair is located in the hills east of Piedmont in a valley formed by the Hayward Fault...

that cross the fault.

Highway 24

State Highway 24

California State Route 24

, connecting Oakland to Orinda, Lafayette, and Walnut Creek through the Caldecott Tunnel

Caldecott Tunnel

The Caldecott Tunnel is a three bore highway tunnel between Oakland, California and Contra Costa County, California. The east-west tunnel is signed as a part of State Route 24, which is also known as the William Byron Rumford...

, 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 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 more likely to disable the offshore causeway portions of Interstate Highway 80 (the Eastshore Freeway), since it 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

Placer mining

Placer mining is the mining of alluvial deposits for minerals. This may be done by open-pit or by various surface excavating equipment or tunneling equipment....

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

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

and plastic foam box structures to support a road.) Similar conditions underlie the eastern approach roads 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 eastern terminus of the San Francisco – Oakland Bay Bridge. As the bulk of cargo containers from the Port of Oakland

Port of Oakland

The Port of Oakland was the first major port on the Pacific Coast of the United States to build terminals for container ships. It is now the fifth busiest container port in the United States, behind Long Beach, Los Angeles, Newark, and Savannah...

travel on these two roads, the disabling of both would cause severe disruption of west coast import and export goods, owing to the consequent overloading of other West Coast container handling ports. Such disruption would be minor compared to that which could be produced by a large southern California earthquake, as the bulk of west coast container traffic is through the ports of Long Beach

Port of Long Beach

The Port of Long Beach, also known as Long Beach’s Harbor Department, is the 2nd busiest container port in the USA. It adjoins the separate Port of Los Angeles. Acting as a major gateway for U.S.-Asian trade, the port occupies of land with of waterfront in the city of Long Beach, California...

and Los Angeles

Port of Los Angeles

The Port of Los Angeles, also called Los Angeles Harbor and WORLDPORT L.A, is a port complex that occupies of land and water along of waterfront. The port is located on San Pedro Bay in the San Pedro neighborhood of Los Angeles, approximately south of downtown...

.

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

Interstate 580 (California)

crosses the fault twice, and runs very close to the fault between the intersections with State Route 13

State Route 13 (California)

State Route 13 is a state highway in California. It is a short loop in Alameda County currently built from Interstate 580 in Oakland to Interstate 80/Interstate 580 in Berkeley....

(the Warren Freeway) and Interstate 238.

Eastern span of the San Francisco – Oakland Bay Bridge

The 1989 Loma Prieta earthquake

Loma Prieta earthquake

caused 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. Engineers and much of the public have 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. A replacement eastern span is currently under construction, with completion projected for late 2013 (originally 2010).

Railroads

Parallel to 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

Port of Oakland

(Union Pacific

Union Pacific Railroad

The Union Pacific Railroad , headquartered in Omaha, Nebraska, is the largest railroad network in the United States. James R. Young is president, CEO and Chairman....

and BNSF

BNSF Railway

The BNSF Railway is a wholly owned subsidiary of Berkshire Hathaway Inc., and is headquartered in Fort Worth, Texas. It is one of seven North American Class I railroads and the second largest freight railroad network in North America, second only to the Union Pacific Railroad, its primary...

railroads) and by Amtrak

Amtrak

The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...

passenger traffic to the Pacific Northwest and eastward through Reno

Reno, Nevada

Reno is the county seat of Washoe County, Nevada, United States. The city has a population of about 220,500 and is the most populous Nevada city outside of the Las Vegas metropolitan area...

and Salt Lake City

Salt Lake City, Utah

Salt Lake City is the capital and the most populous city of the U.S. state of Utah. The name of the city is often shortened to Salt Lake or SLC. With a population of 186,440 as of the 2010 Census, the city lies in the Salt Lake City metropolitan area, which has a total population of 1,124,197...

. Along the north shore of Contra Costa County

Contra Costa County, California

Contra Costa County is a primarily suburban county in the San Francisco Bay Area of the U.S. state of California. As of the 2010 census, it had a population of 1,049,025...

, substantial amounts of pressurized liquid gas, flammable liquids, caustic materials, and various toxics are stored temporarily in bulk railcars adjacent to high speed passenger and freight traffic mainlines, with great potential hazards should 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.

Bay Area Rapid Transit

For current BART information concerning various seismic retrofits see http://www.bart.gov/about/projects/eqs/updates.aspx.

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 a tube structure. The tube 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 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 the connection of additional restraints.

Slip joint

The transbay tube terminates at an under-bay slip joint

Slip joint

A slip joint is a mechanical construction allowing extension and compression in a linear structure.-General forms:Slip joints can be designed to allow continuous relative motion of two components or it can allow an adjustment from one temporarily fixed position to another. Examples of the latter...

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 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 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

Automation

Automation is the use of control systems and information technologies to reduce the need for human work in the production of goods and services. In the scope of industrialization, automation is a step beyond mechanization...

event-related realtime train operational response is considered practical (see below).

Seismic sensor network

BART has installed and continues to enhance a network of seismic sensors (an earthquake warning system

Earthquake warning system

An earthquake warning system is a system of accelerometers, communication, computers, and alarms that is devised for regional notification of a substantial earthquake while it is in progress...

) 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 the epicenter to the 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

Cold War

The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

"duck and cover

Duck and cover

Duck and Cover was a suggested method of personal protection against the effects of a nuclear weapon which the United States government taught to generations of United States school children from the early 1950s into the 1980s. This was supposed to protect them in the event of an unexpected nuclear...

" training of schoolchildren).

Refineries

Of primary concern with respect to the Hayward Fault is the huge Chevron Richmond Refinery

Chevron Richmond Refinery

The Chevron Richmond Refinery is a petroleum refinery in Richmond, California, on San Francisco Bay. It is owned and operated by Chevron Corporation and employs more than 1,200 workers, making it the city's largest employer. The refinery processes approximately of crude oil a day in the...

in Richmond

Richmond, California

. Although founded on better ground than most of 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 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

Martinez, California

Martinez is a city and the county seat of Contra Costa County, California, United States. The population was 35,824 at the 2010 census. The downtown is notable for its large number of preserved old buildings...

, but mostly these plants are exposed to earthquakes from other faults.

Fuel pipelines

Gasoline is continuously shipped under pressure from Richmond and Martinez area refineries through Kinder Morgan Energy Partners pipelines which run under heavily populated East Bay urban areas to tank terminals near San Jose Airport in North San Jose. Aviation fuels are piped from these same refineries to the Oakland Airport. A number of spills have previously occurred due to landslides and such spill and related toxic and flammable material release may be prevalent in a major seismic event. A November 9, 2004, construction accident on this pipeline system in Walnut Creek killed five people. As seen in other worldwide pipeline ruptures, even an instantaneous stop of pumping would take several minutes to significantly lower pipeline pressure after a break, and would likely result in the release of significant amounts of flammable liquid fuels.

Bay Area water supplies

East Bay Municipal Utility District

East Bay Municipal Utility District , colloquially referred to as "East Bay Mud", provides water and sewage treatment for customers in portions of Alameda County and Contra Costa County in California, on the eastern side of San Francisco Bay, including the cities of Richmond, El Cerrito, Hercules,...

(EBMUD) supplies water to 800,000 East Bay customers who live west of the Berkeley Hills

Berkeley Hills

. Prior to the adoption and implementation of a $200 million seismic improvement project all of the water for these customers went through one vulnerable tunnel that crosses the Hayward Fault near the Caldecott Tunnel

Caldecott Tunnel

. As part of this project, that tunnel – the Claremont Tunnel – was seismically retrofitted. Additionally, EBMUD created a second route to bring water to these west-of-the-hills customers through the Southern Loop Bypass near Castro Valley. The Southern Loop was completed in 2002, while the seismic retrofitting of the Claremont tunnel was completed in February 2007.

The Hetch Hetchy Aqueduct

Hetch Hetchy Aqueduct

The Hetch Hetchy Aqueduct is a conveyance of Tuolumne River water runoff from federal lands in Yosemite National Park to San Francisco and its client municipalities in the greater San Francisco Bay Area...

, which supplies 270 to 315 million gallons of water per day to the City of San Francisco and other Bay Area communities, directly crosses the Hayward Fault in Fremont

Fremont, California

. A 2002 report by the Bay Area Economic Forum suggests that a breakdown in the aqueduct due to an earthquake could cut off Hetch Hetchy water to the Bay Area for 60 days. In addition to depriving 85% of San Francisco residents of their drinking water, this would cut off supplies for firefighting and water-intensive industry, causing economic damage of $17.2-28.7 billion.

Lake Temescal

The fault continues north under the eastern margin of Lake Temescal

Temescal Regional Park

Temescal Regional Park formerly Lake Temescal Regional Park is an East Bay Regional Park District regional park in Oakland, California.The park has Lake Temescal as its main attraction in addition to trails, picnic sites, forest, and wildlife....

and its dam, which is unlikely to fail since it has been completely reinforced by the extensive earth fill supporting Highway 24.

University of California, Berkeley

Many of the structures at the UC Berkeley academic campus have been self rated as having "poor" earthquake performance. Numerous chemical, radiological, and biohazardous materials are present (in relatively small quantities) on campus and on the associated Lawrence Berkeley National Laboratory

Lawrence Berkeley National Laboratory

The Lawrence Berkeley National Laboratory , is a U.S. Department of Energy national laboratory conducting unclassified scientific research. It is located on the grounds of the University of California, Berkeley, in the Berkeley Hills above the central campus...

, in the hills above the university. However, the University has undertaken an extensive retrofitting project over the past decade to systematically retrofit all academic buildings on Campus to withstand a significant earthquake.
Memorial Stadium

Further north the fault passes under the lengthwise midline of the football field of California Memorial Stadium

California Memorial Stadium

California Memorial Stadium is an outdoor football stadium on the campus of the University of California in Berkeley. Commonly known as Memorial Stadium, it is the home field for the University of California Golden Bears of the Pacific-12 Conference...

at the University of California, Berkeley

University of California, Berkeley

The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...

. Fault creep since 1923 has offset the walls at the north and south ends 13 inches (33 cm). There are no plans at this time to replace the stadium in its entirety at a more appropriate location, even though its "O" shape may possibly be split into two "C"s. One possible site for a replacement lies immediately to the east in Strawberry Canyon, although this has significant environmental problems, and would require an east-west alignment rather than the traditional north-south orientation. While there is only a small probability of an earthquake on this fault while the stadium is occupied, the results could be deadly.

Extensive upgrades are currently underway including replacement of the football

American football

American football is a sport played between two teams of eleven with the objective of scoring points by advancing the ball into the opposing team's end zone. Known in the United States simply as football, it may also be referred to informally as gridiron football. The ball can be advanced by...

players' facilities, and a seismic retrofit. The work has been the subject of several lawsuits from neighborhood and environmental groups, who are concerned about such extensive construction on top of a major earthquake fault. As this will take more than a year to complete, the Cal Bears will play at AT&T Park

AT&T Park

AT&T Park is a ballpark located in the South Beach neighborhood of San Francisco, California. Located at 24 Willie Mays Plaza, at the corner of Third and King Streets, it has served as the home of the San Francisco Giants of Major League Baseball since 2000....

in San Francisco for one season. Some information concerning the retrofit is available, the changes involving cutting portions of the stadium into large independent sections, demolishing portions over the rubble zone, and building new bridging sections that rest upon floating mats (foundations that do not penetrate the surface, rather sitting upon plastic sheets over level graded gravel or sand) where they pass over and near the fault, with appropriate sliding connections between the sections for the safety of spectators.

Electrical and communication system disruption

Affected areas are likely to be without electrical power for an extensive period. This in turn can make fuel supplies for vehicles and emergency generators unavailable locally and impact both domestic water, industrial water, sewage plants, and drainage pumping. Due to the extensive use of point of sale scanners and registers in supermarkets this could also impact the ability of stores to sell essential items such as groceries and to preserve frozen food items, as well as terminating cable TV and most internet access.

Cellphone and most landline telephone service, while theoretically survivable for a short time on battery and emergency power, could instead suffer immediate disruption from ground shaking effects.

Cities affected

Some of the cities in the eastern bay shore and south bay region near this fault include Richmond

Richmond, California

, El Cerrito

El Cerrito, Contra Costa County, California

, Berkeley

Berkeley, California

, Albany

Albany, California

Albany is a city in Alameda County, California, United States. The population was 18,539 at the 2010 census.-History:In 1908, a group of local women protested the dumping of Berkeley garbage in their community...

, Emeryville

Emeryville, California

Emeryville is a small city located in Alameda County, California, in the United States. It is located in a corridor between the cities of Berkeley and Oakland, extending to the shore of San Francisco Bay. Its proximity to San Francisco, the Bay Bridge, the University of California, Berkeley, and...

, Kensington

Kensington, California

Kensington is an unincorporated community and census-designated place located in the East Bay, part of the San Francisco Bay Area, in Contra Costa County, California, United States. The population was 5,077 at the 2010 census.- Law and government :Kensington is an unincorporated area of Contra...

, Oakland

Oakland, California

Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...

, Piedmont

Piedmont, California

Piedmont is a small, affluent city in Alameda County, California, United States. It is surrounded by the city of Oakland. The population was 10,667 at the 2010 census. Piedmont was incorporated in 1907 and was developed significantly in the 1920s and 1930s...

, San Leandro

San Leandro, California

, San Lorenzo

San Lorenzo, California

San Lorenzo , also known as San Lorenzo Village is a census-designated place in Alameda County, California, United States. The population was 23,452 at the 2010 census.-Geography:...

, Castro Valley

Castro Valley, California

Castro Valley is a census-designated place in Alameda County, California, United States. As of the 2000 census, it is the fifth most populous unincorporated area in California, and the twenty-third in the United States...

, Hayward

Hayward, California

, Union City

Union City, California

Union City is a city in Alameda County, California, United States. It was incorporated in 1959, combining the communities of Alvarado and Decoto. Alvarado was the original county seat of Alameda County, and the site of the first county courthouse is a California Historical Landmark . The city...

, Fremont

Fremont, California

, Newark

Newark, California

Newark is a city in Alameda County, California, United States. It was incorporated as a city in September 1955. Newark is an enclave, completely surrounded by the city of Fremont. Its population was 42,573 at the 2010 census.-Geography:...

, Milpitas

Milpitas, California

Milpitas is a city in Santa Clara County, California. It is a suburb of the major city of San Jose, California. It is located with San Jose to its south and Fremont to its north, at the eastern end of State Route 237 and generally between Interstates 680 and 880 which run roughly north/south...

, Niles, and portions of San Jose

San Jose, California

San Jose is the third-largest city in California, the tenth-largest in the U.S., and the county seat of Santa Clara County which is located at the southern end of San Francisco Bay...

.

Similar dangerous soil conditions and insufficiently resistant buildings are also on the southern, western and northern boundaries of San Francisco and San Pablo bays and would also be severely affected by a major earthquake on the Hayward fault. As that portion includes the so-called Silicon Valley

Silicon Valley

Silicon Valley is a term which refers to the southern part of the San Francisco Bay Area in Northern California in the United States. The region is home to many of the world's largest technology corporations...

, the potential economic disruption due to destruction of works in progress and the dismantling of microelectronics fabrication plants could have an economic effect extending worldwide. The current estimates of the probability of a major earthquake on any of the numerous regional faults range up to 70 percent within the thirty year period 2000-2029. A recent quiet period following many years of minor activity is considered to be particularly ominous by many, although geologists have not yet been able to predict earthquakes with any useful accuracy. They do warn that all residents of the region should be prepared for a large event and its subsequent effects (e. g., lack of water, firefighting, first aid, electricity, motor and heating fuels, etc.) and that much life-safety protective work remains to be done.

Retrofits for survivability

It is primarily the likelihood of a severe earthquake on the Hayward or San Andreas faults that has spurred a substantial effort to retrofit

Seismic retrofit

and sometimes replace large structures at risk, particularly the eastern and western spans of the San Francisco – Oakland Bay Bridge, the San Francisco

San Francisco City Hall

San Francisco City Hall, re-opened in 1915, in its open space area in the city's Civic Center, is a Beaux-Arts monument to the City Beautiful movement that epitomized the high-minded American Renaissance of the 1880s to 1917. The structure's dome is the fifth largest in the world...

and Oakland

Oakland, California

Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...

city halls, and numerous elevated rail, road, and pedestrian structures and overpass

Overpass

An overpass is a bridge, road, railway or similar structure that crosses over another road or railway...

es. Much work remains to be done in the region and progress is being hampered by budget constraints imposed by trickle down federal-state-regional deficits, design and construction delays due to state and local political bickering over design, and unexpectedly high steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

and cement

Cement

In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...

costs due to the extensive construction work being done in China

People's Republic of China

China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

. Nonetheless, Bay area cities and counties have long expected a major earthquake and as a result all building in the past 30 years has been required to adhere to strict guidelines regarding earthquake resistance. Of all the earthquake prone regions of the world, the San Francisco Bay Area is among the most prepared structurally for the eventuality of a major quake while remaining grossly unprepared in both civil response planning and in the retrofitting of older buildings.

Virtual tour

The Google Earth

Google Earth

Google Earth is a virtual globe, map and geographical information program that was originally called EarthViewer 3D, and was created by Keyhole, Inc, a Central Intelligence Agency funded company acquired by Google in 2004 . It maps the Earth by the superimposition of images obtained from satellite...

website, in cooperation with the United States Geological Survey

United States Geological Survey

, has prepared a virtual helicopter tour of the fault, with much additional information available through the tour. Potentially dangerous landslide areas are also marked, showing great areas beyond the fault that could be rendered uninhabitable by a major event.

Special exhibit

Fremont

Fremont, California

Earthquake Exhibit: The Hayward Fault Exposed

This geotourism

Geotourism

Geotourism is "best practice" tourism that sustains, or even enhances, the geographical character of a place, such as its culture, environment, heritage, and the well-being of its residents....

exhibit (April through October 2006, now closed) featured a 12- to 15 feet (5 m) deep pit exposing the Hayward Fault, which could be viewed "face to face" from a shaded platform by descending a staircase. Significant features were noted and marked. Similar trench excavations are used in the determination of the frequency and magnitude of prehistoric earthquakes and to determine the location of latent faults as part of the science of Paleoseismology

Paleoseismology

Paleoseismology looks at geologic sediments and rocks, for signs of ancient earthquakes. It is used to supplement seismic monitoring, for the calculation of seismic hazard...

Extensive additional interpretive material concerning the geology and seismology of the Bay Area was presented for viewing, most of which is currently accessible online.http://www.msnucleus.org/haywardfault/index.htm
Funding and organization for a permanent exhibit at this location is being actively sought, with planning in progress.http://www.msnucleus.org/haywardfault/proposal07.pdf

External links

USGS Satellite Maps - Hayward Fault This includes links to the Google Earth virtual tour of the fault.
"It's Not Our Fault"', article in the East Bay Express
Bart seismic study document (PDF)
The geology of "Bear Territory" - University of California at Berkeley geology tour
Tour of the Hayward Fault - California State University at Hayward web site with images showing fault creep.
Fremont Earthquake Exhibit - The Hayward Fault Exposed msnucleus.org, K-12 math and science education site.
Recent significant events in the California region with opportunity to report via did you feel it?
Introduction to the Hayward Fault USGS website with deep cross-section illustrations.
ABAG shaking hazard maps - select locality, generating fault, and view ground shaking projections.
KQED Quest video segment on the Hayward Fault

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Tectonics of the Hayward Fault Zone

Rodgers Creek Fault Zone

Calaveras Fault

Notable earthquakes

Prehistoric earthquakes

Recent activity

Probability of future activity

Principal segments

Fault effects

Fault creep

Earthquake shaking

Bayside soil conditions

Ancient and prehistoric massive landslides and modern instabilities

Potentially impacted structures and features

Freeways and overcrossings

Eastern span of the San Francisco – Oakland Bay Bridge

Railroads

Bay Area Rapid Transit

Refineries

Fuel pipelines

Bay Area water supplies

Lake Temescal

University of California, Berkeley

Electrical and communication system disruption

Cities affected

Retrofits for survivability

Virtual tour

Special exhibit

See also

External links