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1979 Coyote Lake Earthquake
The 1979 Coyote Lake earthquake occurred at on August 6 with a Moment magnitude scale, moment magnitude of 5.7 and a maximum Mercalli intensity scale, Mercalli Intensity of VII (''Very strong''). The shock occurred on the Calaveras Fault near Coyote Lake (Santa Clara County, California), Coyote Lake in Santa Clara County, California and resulted in a number of injuries, including some that required hospitalization. Most of the $500,000 in damage that was caused was non-structural, but several businesses were closed for repairs. Data from numerous strong motion instruments was used to determine the type, depth, and extent of slip. A non-destructive aftershock sequence that lasted throughout the remainder of the month was of interest to seismologists, especially with regard to fault creep, and following the event local governments evaluated their response to the incident. Tectonic setting The San Andreas Fault system (SAF) is a network of right-lateral Fault (geology)#Strike-slip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peak Ground Acceleration
Peak ground acceleration (PGA) is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an wikt:accelerogram, accelerogram at a site during a particular earthquake. Earthquake shaking generally occurs in all three directions. Therefore, PGA is often split into the horizontal and vertical components. Horizontal PGAs are generally larger than those in the vertical direction but this is not always true, especially close to large earthquakes. PGA is an important parameter (also known as an intensity measure) for earthquake engineering, The design basis earthquake ground motion (DBEGM) is often defined in terms of PGA. Unlike the Richter magnitude scale, Richter and Moment magnitude scale, moment magnitude scales, it is not a measure of the total seismic scales#Magnitude and intensity, energy (magnitude, or size) of an earthquake, but rather of how hard the earth shake ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extensional Tectonics
Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body's crust or lithosphere. Deformation styles The types of structure and the geometries formed depend on the amount of stretching involved. Stretching is generally measured using the parameter ''β'', known as the ''beta factor'', where : \beta = \frac \,, ''t''0 is the initial crustal thickness and ''t''1 is the final crustal thickness. It is also the equivalent of the strain parameter ''stretch''. Low beta factor In areas of relatively low crustal stretching, the dominant structures are high to moderate angle normal faults, with associated half grabens and tilted fault blocks. High beta factor In areas of high crustal stretching, individual extensional faults may become rotated to too low a dip to remain active and a new set of faults may be generated. Large displacements may juxtapose syntectonic sediments against metamorphic roc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parapet
A parapet is a barrier that is an extension of the wall at the edge of a roof, terrace, balcony, walkway or other structure. The word comes ultimately from the Italian ''parapetto'' (''parare'' 'to cover/defend' and ''petto'' 'chest/breast'). Where extending above a roof, a parapet may simply be the portion of an exterior wall that continues above the edge line of the roof surface, or may be a continuation of a vertical feature beneath the roof such as a fire wall or party wall. Parapets were originally used to defend buildings from military attack, but today they are primarily used as guard rails, to conceal rooftop equipment, reduce wind loads on the roof, and to prevent the spread of fires. In the Bible the Hebrews are obligated to build a parapet on the roof of their houses to prevent people falling (Deuteronomy 22:8). Parapet types Parapets may be plain, embattled, perforated or panelled, which are not mutually exclusive terms. *Plain parapets are upward extensions of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berkeley Seismological Laboratory
The Berkeley Seismological Laboratory (BSL) is a research lab at the Department of Geology at the University of California, Berkeley. It was created from the Berkeley Seismographic Stations, a site on the Berkeley campus where Worldwide Standard Seismographic Network instruments were first deployed in 1959. Today, BSL's mission is to "support fundamental research into all aspects of earthquakes, solid earth processes, and their effects on society". An experimental early warning system developed by BSL issued a warning 10 seconds before the 6.0 magnitude earthquake that hit the Napa region on August 24, 2014. Such a warning system could potentially give people time to take cover in the event of a quake, preventing injuries caused by falling debris, automatically stopping trains or shutting off gas lines. The system, developed in conjunction with the United States Geological Survey (USGS), the California Institute of Technology and the University of Washington, will eventually cove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hollister, California
Hollister is a city in and the county seat of San Benito County, located in the Central Coast region of California. With a 2020 United States census population of 41,678, Hollister is one of the largest cities in the Monterey Bay Area and a member of the Association of Monterey Bay Area Governments. The city is an agricultural town known primarily for its local Blenheim apricots, olive oil, vineyards, pomegranates, and chocolate. History The area of modern-day Hollister was historically inhabited by the Mutsun band of the Ohlone Native Americans. With the construction of Mission San Juan Bautista in 1797, the Ohlone were forced into the California mission system. The town of Hollister was founded on November 19, 1868, by William Welles Hollister on the grounds of the former Mexican land-grant Rancho San Justo. At the time, Hollister was located within Monterey County, until San Benito County was formed by the California Legislature in 1874 from portions of Monterey, Merc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gilroy, California
Gilroy is a city in Northern California's Santa Clara County, south of Morgan Hill and north of San Benito County. Gilroy is the southernmost city in the San Francisco Bay Area, with a population of 56,766 as of the 2019 U.S. Census Projections. Gilroy's origins lie in the village of San Ysidro that grew in the early 19th century out of Rancho San Ysidro, granted to Californio ranchero Ygnacio Ortega in 1809. Following Ygnacio's death in 1833, his daughter Clara Ortega de Gilroy and son-in-law John Gilroy inherited the largest portion of the rancho and began developing the settlement. When the town was incorporated in 1868, it was renamed in honor of John Gilroy, a Scotsman who had emigrated to California in 1814, naturalized as a Mexican citizen, adopted the Spanish language, and converted to Catholicism, taking the name of Juan Bautista Gilroy. Gilroy is known for its garlic crop and the annual Gilroy Garlic Festival, featuring various garlicky foods such as garlic ice cream ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hayward Fault Zone
The Hayward Fault Zone is a right-lateral strike-slip geologic fault zone capable of generating destructive earthquakes. This fault is about long, situated mainly along the western base of the hills on the east side of San Francisco Bay. It runs through densely populated areas, including Richmond, El Cerrito, Berkeley, Oakland, San Leandro, Castro Valley, Hayward, Union City, Fremont, and San Jose. The Hayward Fault is parallel to the San Andreas Fault, which lies offshore and through the San Francisco Peninsula. To the east of the Hayward Fault lies the Calaveras Fault. In 2007, the Hayward Fault was discovered to have merged with the Calaveras Fault east of San Jose at a depth of , with the potential of creating earthquakes much larger than previously anticipated. Some geologists have suggested that the Southern Calaveras should be renamed as the Southern Hayward. North of San Pablo Bay is the Rodgers Creek Fault, which was shown in 2016 to be linked with the Hayward Faul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge University Press
Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by Henry VIII of England, King Henry VIII in 1534, it is the oldest university press A university press is an academic publishing house specializing in monographs and scholarly journals. Most are nonprofit organizations and an integral component of a large research university. They publish work that has been reviewed by schola ... in the world. It is also the King's Printer. Cambridge University Press is a department of the University of Cambridge and is both an academic and educational publisher. It became part of Cambridge University Press & Assessment, following a merger with Cambridge Assessment in 2021. With a global sales presence, publishing hubs, and offices in more than 40 Country, countries, it publishes over 50,000 titles by authors from over 100 countries. Its publishing includes more than 380 academic journals, monographs, reference works, school and uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calaveras Reservoir
Calaveras Reservoir is located primarily in Santa Clara County, California, with a small portion and its dam in Alameda County, California. In Spanish, Calaveras means "skulls". The reservoir is fed mainly by Arroyo Hondo and Calaveras Creek. Lying in the Calaveras Valley, the region is geologically active with the Calaveras Fault parallel to and to the west of the dam site. The seismic hazard forced replacement of the original dam. The replacement dam began construction in 2011 and was completed in 2019. The Calaveras Valley has diverse wildlife including deer, coyotes, squirrels, turkey vultures, red-winged blackbirds, yellow-billed magpies, red-tailed hawks, brewer's blackbirds, purple martins, barn swallows, bullock's orioles, and warblers. Since at least 2008, a pair of bald eagles has nested regularly. History In the 19th century, the Calaveras Valley which the reservoir now fills was primarily an agricultural region known for its production of hay, strawberries, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1868 Hayward Earthquake
The 1868 Hayward earthquake occurred in the San Francisco Bay Area, California, United States on October 21. With an estimated moment magnitude of 6.3–6.7 and a maximum Mercalli intensity of IX (''Violent''), it was the most recent large earthquake to occur on the Hayward Fault Zone. It caused significant damage and a number of deaths throughout the region, and was known as the "Great San Francisco earthquake" prior to the 1906 San Francisco earthquake and fire. Earthquake The earthquake occurred at 7:53 a.m. on October 21, 1868. Its epicenter was likely located near Hayward, California, and its magnitude has been estimated to have been 6.3–6.7 on the moment magnitude scale. At the surface, ground rupture was traced for , from San Leandro to what is now the Warm Springs District in Fremont. Damage The town of Hayward experienced the most damage, with nearly every building destroyed or significantly damaged in the earthquake. The Alameda County Courthouse in San Lea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aseismic Creep
In geology, aseismic creep or fault creep is measurable surface displacement along a fault in the absence of notable earthquakes. Aseismic creep may also occur as "after-slip" days to years after an earthquake. Notable examples of aseismic slip include faults in California (e.g. Calaveras Fault, Hayward Fault, and San Andreas Fault). Causes Aseismic creep accommodates far-field motions on localized zones of deformation at tectonic plate boundaries. The underlying causes of aseismic creep are primarily attributed to poor frictional strength of the fault, low normal stress acting on the fault in the shallow crust, and excessive pore-fluid pressures, which limit the viable amount of normal stress on a fault. The frictional reaction of geologic materials can explain the transition from seismic to aseismic deformation with depth. Friction along faults can cause sudden slips with associated stress drops (earthquakes), along with phases of no motion as stress recharges. Measurements ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hayward Fault
The Hayward Fault Zone is a right-lateral strike-slip geologic fault zone capable of generating destructive earthquakes. This fault is about long, situated mainly along the western base of the hills on the east side of San Francisco Bay. It runs through densely populated areas, including Richmond, El Cerrito, Berkeley, Oakland, San Leandro, Castro Valley, Hayward, Union City, Fremont, and San Jose. The Hayward Fault is parallel to the San Andreas Fault, which lies offshore and through the San Francisco Peninsula. To the east of the Hayward Fault lies the Calaveras Fault. In 2007, the Hayward Fault was discovered to have merged with the Calaveras Fault east of San Jose at a depth of , with the potential of creating earthquakes much larger than previously anticipated. Some geologists have suggested that the Southern Calaveras should be renamed as the Southern Hayward. North of San Pablo Bay is the Rodgers Creek Fault, which was shown in 2016 to be linked with the Hayward Faul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
