scientific and educational geological slide set Scientists have scrutinized the creep of land along the Hayward fault for years using a network of more than 30 ground-based instruments, but only nine such instruments monitored the longer Calaveras fault. The compressive pressure is manifest in a significant thrust fault nearby on the western slope of the mountain, the Mount Diablo Thrust Fault,[3] the most active of its kind in the region and which is also capable of producing significant local earthquakes affecting the Alamo-Danville area. Using this picture, they calculated new estimates for the amount of energy stored in stresses along the fault.. The structure of the faults is important because ruptures cant spread if theyre not directly connected, Chaussard said. It splits off from the San Andreas several miles south of the valley. These cracks are the harbingers of the major seismic disaster that will one day affect millions of people in the region. Unfortunately, that means many of the features so interesting to 
The sidewalks and 6th Street are also offset. The entrance to the Oakland Zoo is marked by the fault; the zoo even notes the location of the fault on its grounds with a sign. Contact Update: To the dismay of many, the city of Hollister repaired this "broken" curb! Another way to assess the Hayward Faults potential damage is through FEMAs hazard modeling program, HAZUS, which allows users to select variables such as the location of an earthquakes epicenter, the length of a rupture, the magnitude and depth of a quake, and the time of day when it occurs. Google for other web pages about the Calaveras Fault. Please be respectful of the residents' privacy. Alteration of rocks and minerals at depth forms a host of slippery minerals that don't allow stress to build up to high levels. etc, please let me know! In California, the plate is sliding northwestward along a transform boundary, the San Andreas Fault, toward the subduction zone. info@ngdc.noaa.gov AltaVista for web pages that link to this one. (Strike-slip means movement in the horizontal direction). It is possible that each of these quakes could have produced higher casualties if they had occurred later in the day.). The creep rate apparently varies in an unpredictable way. At 2 a.m., most people would be home asleep in wood-framed, single-family homes that are unlikely to collapse completely. (Above) "Faulting For Dummies." The scientific community has mapped the fault and assessed the risk.
On the campus of Contra Costa Community College, the Hayward Fault distorts once-straight brick paving stones. Notice in all the photos how the distortion always bends Begin at Dunne Park. Required fields are marked *. Time for that picnic in the park! You can also do a web search like this: "san andreas" site:usgs.gov, Cool geology, awesome geology, hidden gems, geologic trips, geologic places, field trips, http://scedc.caltech.edu/recent/index.html, http://pubs.er.usgs.gov/publication/pp1515. Prior to the 2014 South Napa earthquake, it was the most powerful quake to hit the Bay Area since the Loma Prieta earthquake of 1989, and the largest on the Calaveras Fault since 1984. As with all offsets on the Hayward, the sense of movement is right-lateral; in other words, when looking across the fault, the other side appears to be moving to one's right. look for the small ridge to the right (West) of the highway leaving the road at Stresses are also produced by offset and converging slip-strike motions between the Calaveras and Clayton-Marsh Creek-Greenville Fault that continue to elevate Mount Diablo. Traveling over the water will be no less difficult; HAZUS estimates between 43 and 78 bridges will be damaged.
BART has made efforts to retrofit its infrastructure, but a 2002 study estimated that major damage from an earthquake to the underwater trans-bay tunnel, through which the rail line travels, could shut down the BART system for two to three years, with disastrous effects on the local economy. What would a big quake on the Hayward Fault do? HAZUS predicts casualties in these ranges: Table showing HAZUS predictions of casualties for three different magnitude scenarios. SEP's WWW site. and the Calaveras; all are part of the San Andreas fault system. of seismic hazards from San Francisco bay area faults.
(Locust street curves around the base of the (Above) A very crooked house on the fault. But all they have to do is look. The Pacific Plate is a major section of the Earth's crust, gradually expanding by the eruption of magma along the East Pacific Rise to the southeast. The San Andreas continues up the San Francisco penninsula to Mussel Rock, and the Calaveras cuts through the hills east of Gilroy and Morgan Hill. The Kobe quake also caused 1.5 meters of horizontal displacement on the ground; given the energy accumulated since the 1868 quake and the displacement observed in that event, scientists expect about 2 meters of horizontal displacement on the Hayward Fault, according to a 2008 fact sheet from USGS. Most of the Bay Areas water is impounded in reservoirs, in hills far out of sight and out of mind of the residents. Posted in: There are other pop-up blocks to the north and south. The U.S. Geological Survey describes the Hayward Fault as "the single most urbanized earthquake fault in the United States." the faults in the San Andreas system are not ``stuck'': East of San Francisco, across the muddy, green waters of San Francisco Bay, sits a smaller fracture in the crust: the Hayward Fault. Hollister is being If you live 80 years, you'll see the sidewalks and streets in Hollister move by 480 mm to 960 mm (20 to 40 inches). It passes through or near the cities of Alamo, Danville, San Ramon, Dublin, Pleasanton, Sunol, Milpitas, San Jose, Gilroy, and Hollister. these sites every few years.).
To the east of the Hayward-Rodgers Creek fault, the Calaveras fault extends 123km (76mi), splaying from the San Andreas fault near Hollister and terminating at Danville at its northern end. The last large event was the 1984 Morgan Hill event and the last moderate earthquake was the 2007 Alum Rock event. In Berkeley, the fault runs beneath the University of California at Berkeleys football stadium, where offset on the south wall can be seen. The last quake was 148 years ago, so we currently sit within that range. ripped in two, Last summer, a startling article appeared in The New Yorker magazine outlining what could happen to the Pacific Northwest in the event of a large earthquake resulting from a full rupture of the Cascadia Subduction Zone. A new study has found that the Hayward and Calaveras faults are connected underground, a fact that could make earthquakes that occur along the faults bigger.Credit: Leonard G. Scientists have used satellites to more accurately measure the slow creep of land along the Calaveras and Hayward faults east of the San Francisco Bay, a finding that helped the researchers estimate the magnitude of future earthquakes. Not only are homebuyers not protected by any required disclosures in contracts, but there has also been a failure to prepare for the inevitability of this quake.
If liquefaction damages even small sections of such freeways, they become unusable. Chaussard explained the results in a poster Wednesday morning during the American Geophysical Unions Fall Meeting in San Francisco. that the motion is predominantly horizontal, with the land on the West side 
Credit: Steven Newton. this ``Virtual Field Trip'' on Along the Calaveras and Hayward faultssmaller cracks on top of the platesthe land also moves steadily, a movement that geologists call creep. New content about AGU research can be found on Eos and the AGU newsroom. To the east lies the Clayton-Marsh Creek-Greenville Fault. (quoted from [4] The most recent of these was a magnitude 6.2 earthquake near Morgan Hill in 1984. 
For my model runs, I chose an arbitrary epicenter near the Lake Chabot Reservoir dam (which is one of many reservoirs located near the fault that could inundate neighborhoods if the dams fail). We have no excuse not to prepare for the coming quake. Between the faults lies an area of minor faults aligned en echelon known as the Contra Costa Shear Zone.[2]. Hollister, California is located South of the San Francisco Bay area.
(Above) This trash can seems to be holding the North American Plate in place while the Pacific side slides slowly northward. Despite the notoriety of the San Andreas Fault, it is not the greatest seismic threat to the Bay Area. Of the many faults in the Bay Area, the Hayward Fault has the greatest likelihood of producing such an event. Clearly, there is a big difference in the number of deaths predicted by the HAZUS model for this potential Hayward earthquake and the experience in Kobe, with HAZUS estimating an order of magnitude fewer. The slight drop in the park is the trace of the Calaveras fault.
In my nearly two decades of teaching geology in the Bay Area, I have found that surprisingly few people even know where the fault is. The 1995 Kobe quake, a magnitude-6.9 event in southern Japan, has been proposed as the best analogue for a future Hayward earthquake, which is expected to have a similar magnitude and may have a similar rupture length.
Their reconstruction of the geometry of the Hayward and the Calaveras faults provided evidence for an underground connection that scientists have suspected for nearly a decade. The Calaveras Fault was named for Calaveras Creek in Santa Clara County east of San Jose where it was first identified. I recently ran a HAZUS model for a Hayward Fault rupture. As a result of this creep, Start your visit at Dunne Park, bordered by 6th and 7th, West and Powell streets. USGS ShakeMaps showing intensity patterns for the 1984 Morgan Hill (left) and 2007 Alum Rock events, "Characterization of the SFBR Earthquake Sources", http://gsa.confex.com/gsa/2005CD/finalprogram/abstract_85559.htm, https://www.pbs.org/newshour/indepth_coverage/science/1906quake/map6.html, "Historic Earthquakes: Calaveras fault, California". Data Center's Powell changes name to Locust north of 4th Street. They found that the fault has areas that move as much as 0.47 inches per year (12 millimeters per year) and some that remain motionless. (Above) The Calaveras fault, a branch of the San Andreas, creeps through Hollister, displacing everything in its path. The Calaveras has two branches that go around the hill. So if you decide to visit Hollister yourself, Most of their slide sets cost about $30. from San Juan Bautista California cannot "fall into the ocean." (Above) This diagram from the USGS shows the kinds of features found along strike-slip faults like the Calaveras and San Andreas.
(Above) The fault created a small scarp through Dunne Park between 6th and 7th Streets. Begin the walking tour there. in Fremont. Additionally, if freeway overpasses collapse or become too damaged for vehicles to travel underneath them safely, then freeways are rendered useless. Aseismic creep is rare throughout the world, although it occurs on the San Andreas, the Calaveras and the Hayward faults. of the fault moving North. See how the top leans to the left? Corner of Fremont Way and Locust, looking west. This technique, called InSAR for short, uses light reflected off the ground to measure movement, much like radar. Some of the cities which the Calaveras Fault passes through or near are: Alamo, Danville, San Ramon, Dublin, Pleasanton, Sunol, Milpitas, San Jose, Gilroy, and Hollister. I wonder how shelves would fit on the inside? Hollister is located just North of where this happens, (Above) Map from the U.S. Geological Survey. The West Napa Fault in Napa County is believed to be a continuation of the Calaveras Fault north of the Carquinez Strait. Her photographs show this intersection as early as 1971, when offset was minimal. right on top of the Southern end of the Calaveras fault. sites have been monitored in Hollister, one showing 6.6 mm/yr and the Any copying, redistribution or retransmission of any of to just North of Parkfield for the most part along a remarkably narrow Activity on the different segments of the fault includes moderate and large earthquakes as well as aseismic creep. (Above) The San Andreas and Calaveras split south of the Hollister valley. It also happens to sit astride one of the plate boundary faults, the Calaveras, which is slowly but surely tearing the town in half. Note the separation of sidewalk from steps, and the slightly leaning porch posts. They can still remedy the mistakes of the past, however, in part by offering buyouts as an incentive to move people away from the worst zones. Sylvester and Crowell, 1989 Geophysical Union, Washington, D. C. If you can suggest further references, help improve the text, (Above) Displaced sidewalk on the south side of 5th Street just east of Powell, looking east. Site. National Geophysical
Credit: Steven Newton. It is believed to link with the Hayward fault, as well as the West Napa Fault, north of the Carquinez Strait. One way to assess this question is to compare a potential large Hayward quake to events of similar size in areas of similar population. The USGS continuously monitors their activity. This blog to visiting geologists about their famous fault This is an archive of AGU's GeoSpace blog through 1 July 2020. This site is near Arroyo Agua Caliente Park, a name that suggests a hot spring always a good indicator of fault activity. Please visit our sponsors to help keep Roc Doc Travel going! Calaveras fault zone at Hollister, California, Seism. It is also being subducted far to the northwest into the Aleutian Trench under the North American Plate well north of San Francisco. Yard of the beautiful blue house on the north side of 6th Street across from the park, looking east. Underscoring this risk, the Calaveras Reservoirs earthen dam, constructed in 1925, has been deemed so seismically vulnerable that a replacement dam farther downstream is currently under construction. The Calaveras fault here is unusual because it creeps, moving a few millimeters per year, instead of storing up energy and releasing it all in a big earthquake. rights and stay out of people's yards!!! Its just a matter of time before a large earthquake on the Hayward Fault happens, but how we choose to prepare or not to prepare will make a tremendous difference to those caught in the aftermath of this inevitable disaster. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Your email address will not be published. expect to see for yourself most of what I show below, In addition to the Calaveras creep found with InSAR, the team also found that creep was occurring more than 9.3 miles (15 kilometers) farther south along the Hayward fault than previously known.
New research shows that two faults in the San Andreas system, the Hayward and Calaveras faults, are actually connected underground.Credit: NASA. The quake would essentially cut off large parts of the Bay Area. Go visit some other creeping fault locales. However, such traffic jams may never materialize if damage to road infrastructure is so severe that people cannot get on the freeways at all. (Above) This garage wall is bent. I set up the model runs under three scenarios with varying event magnitudes: low (magnitude 6.7), moderate (7), and major (7.2). But if a quake occurred at 2 p.m. on a weekday, many people would be at work or school in vulnerable structures constructed with brick walls and unreinforced masonry. Assessments in January 2008[6] suggest that the northern Calaveras fault (the portion between Sunol and Danville) may be more likely to fail in the next few decades than previously thought. (It's now considered to be within commuting range of San Jose.) ", The creep rate has varied from year to year between 6 and 12 mm/year (1/4 to 1/2 inch per year). Today, Hayward has about 149,000 people, and 2.6 million people live in the immediate vicinity of the fault. the San Andreas, the Hayward, I have split the tour up into several pages so that there aren't too many The San Francisco Bay Area also suffers from the unfortunate confluence of large populations and active faults. That makes it a favorite laboratory for Earth Scientists and students to see faulting in slow-motion. Hollister is a quaint, friendly, enjoyable town in farm country, and a pleasant day trip from the Bay Area, Monterey, or the Central Valley. Assessing casualties is more challenging. zone running right through the middle of town. A long-time friend of mine has lived there all his life and wouldn't trade it for any place. For instance, a lot depends on where people are when the quake hits. They also found that if a slip occurs along the southern part of the Calaveras, it could unleash a magnitude 7.1 earthquake, larger than previously thought. When the last quake struck the Hayward Fault in 1868, the Bay Area was sparsely populated. All of these are ``right-lateral strike-slip faults'', which means These four fault structures are some of the major faults in California at the latitude of San Francisco. Together, these two observations define right-lateral strike-slip motion. The entire length of the Hayward Fault runs through densely populated cities such as Oakland, Fremont and Berkeley (shown here), and is not far from the metropolises of San Francisco (background) and San Jose. And several of the system's reservoirs (shown on the map) sit directly on or very close to faults. Credit: Steven Newton. erased). Chris Cesareis a science communication graduate student at UC Santa Cruz. (Map) Hollister is SE of the San Francisco Bay Area. Since many of these bridges form choke-points in traffic flow, damage to even a few could create epic traffic jams. right on top of the Southern end of the Calaveras fault. tourists tramping around in their yards without permission. (Above) This wall and sidewalk have been displaced since the 1930's. "Hayward, Calaveras faults may be connected, geologist says", Tracking the Elusive Calavaras Fault from Sunol to San Ramon, Rescue Lineament-Bear Mountains fault zone, https://en.wikipedia.org/w/index.php?title=Calaveras_Fault&oldid=1029085140, Geology of Contra Costa County, California, Geology of Santa Clara County, California, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 17 June 2021, at 20:07. But creep on the Hayward Fault does allow us to map its trace precisely, and to see where large ruptures might happen when the fault does break again. [1] It runs east of the San Andreas, diverging from it in the vicinity of Hollister, California, and is responsible for the formation of the Calaveras Valley there. (For those not metrically inclined, 12 mm/yr is half an inch a year. This slip deficit suggests that creep will not prevent future quakes, according to Kristy Tiampo, now at the University of Colorado at Boulder, and her colleagues, who explored the issue in a 2013 study in Earth and Planetary Science Letters. I think you'll like Hollister. More than 400,000 commuters use the BART system on weekdays. plus many more sights I didn't include. In the Bay area A 2010 report by the Earthquake Engineering Research Institute noted the 2 meters of expected offset in the BART Berkeley Hills Tunnel, versus the 0.6 meters of displacement it was engineered to accommodate, could put the tunnel out of commission indefinitely..
It's a kind of "Faults For Dummies! there are three major faults, from West to East The dark black in the center of the image is a portion of the San Andreas Fault that runs west of the San Francisco Bay, near San Mateo. Household gas meters could be required to have motion-activated automatic shut-off switches, a technology widely used in Japan to reduce post-quake fire danger. Between the San Andreas Fault and the Calaveras Fault lies the Hayward Fault, which diverges from the Calaveras Fault east of San Jose, California. Save my name, email, and website in this browser for the next time I comment. The Hetch Hetchy water system, which provides water to San Francisco, is extraordinarily vulnerable to seismic disruption as it moves water across several faults.
In San Leandro, the Hayward Fault runs near the Fairmont Hospital and the earthen dam holding back the Lake Chabot Reservoir. Now, Chaussard and her colleagues have used 19 years of satellite measurements to study the Hayward and Calaveras complex. Park Hill is a "pop-up block" or "pressure ridge," a chunk of Earth's crust that has been squeezed upward by compression between the two faults. Here is a map showing the approximate active trace of the fault for the Ground movement also has the potential to destroy water delivery systems at multiple levels: at the household level, with pipes breaking and flooding homes or unsecured water heaters detaching; at the neighborhood level, with breaks in municipal water lines or water mains; and at the city level, with municipal water treatment plants failing or reservoirs and dams rupturing. Thanks to Charlene McDonald for ``test driving'' the tour and double-checking 945,000). But when might that risk become reality? How will hundreds of thousands of newly homeless people in the region survive absent running water, absent sewage systems, and absent electricity? "Calaveras" is also the name of a California county in the foothills of the Sierra Nevada mountains, some 100 miles (160km) east of Santa Clara County, far from the Calaveras Fault. Repairs for many of these problems, which involve digging up streets and rebuilding major parts of the water infrastructure, would take months to years. The Hetch Hetchy water system is extraordinarily vulnerable to seismic disruption. point out errors or omissions, have images you'd like to donate, The Pacific Northwest is not the only region of the United States in tectonic jeopardy. The worst flooding could happen to the city of Fremont. part of town covered in our tour. the fault through town. The Calaveras Fault shares the same relative motions of the San Andreas. the usual pattern for faults, they continuously ``creep''. All rights reserved. If you can suggest further references, help improve the text, geologists nowadays tend to get conscientiously repaired (in other words, A number of magnitude 6 earthquakes have been recorded on the fault throughout recorded history, the largest of which was a magnitude 6.5 that occurred in 1911 in the Morgan Hill area. (The latter gave its name to the fault when it was first recognized in 1895.) Most people have heard of the San Andreas, which they assume will be the source of the next big quake in the Bay Area, thanks in part to Hollywood disaster movies, such as the dreadful San Andreas, which perpetuate geologic absurdities.
2008-2021. The Calaveras and San Antonio reservoirs store more than 180 million cubic meters of water, perched above the city of Fremont and its 224,000 residents.
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