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1987 Superstition Hills Earthquakes
The 1987 Superstition Hills and Elmore Ranch earthquakes were a pair of earthquakes measuring 6.0 and 6.5 that rattled the Imperial Valley of California. The earthquakes caused damage in Southern California and Mexico, but was limited due to their location in a sparsely populated area. It was felt as far as Las Vegas and Phoenix. More than 90 were injured, and two people were killed in Mexico. Geology The Imperial Valley is a seismically active area in California. It is in this area where the San Andreas Fault and San Jacinto Fault Zone (SJFZ) terminate in the south. This region is a transition zone between the continental transform boundary to oceanic rifting in the Gulf of California. South of the San Andreas Fault and between the Imperial Fault is the Brawley Seismic Zone—the northernmost ridge feature in the Gulf of California ridge–transform boundary. Faults in the Brawley Seismic Zone typically trend northeast, perpendicular to the plate boundary faults. Labeled "cro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territories of the United States by population, most populous U.S. state and the List of U.S. states and territories by area, 3rd largest by area. It is also the most populated Administrative division, subnational entity in North America and the 34th most populous in the world. The Greater Los Angeles area and the San Francisco Bay Area are the nation's second and fifth most populous Statistical area (United States), urban regions respectively, with the former having more than 18.7million residents and the latter having over 9.6million. Sacramento, California, Sacramento is the state's capital, while Los Angeles is the List of largest California cities by population, most populous city in the state and the List of United States cities by population, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Geological Survey
The United States Geological Survey (USGS), formerly simply known as the 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's work spans the disciplines of biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility. The agency was founded on March 3, 1879. The USGS is a bureau of the United States Department of the Interior; it is that department's sole scientific agency. The USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, and Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous slogan, adopted on the occasion of its hundredt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
El Centro, California
El Centro (Spanish for "The Center") is a city and county seat of Imperial County, California, United States. El Centro is the largest city in the Imperial Valley, the east anchor of the Southern California Border Region, and the core urban area and principal city of the El Centro metropolitan area which encompasses all of Imperial County. El Centro is also the largest U.S. city to lie entirely below sea level (). The city, located in southeastern California, is from San Diego and less than from the Mexican city of Mexicali. The city was founded in 1906 by W. F. Holt and C.A. Barker, who purchased the land on which El Centro was eventually built for about and invested $100,000 ($ in dollars) in improvements. The modern city is home to retail, transportation, wholesale, and agricultural industries. There are also two international border crossings nearby for commercial and noncommercial vehicles. El Centro's census population as of 2020 was 44,322, up from 42,598 at the 201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tempe, Arizona
, settlement_type = City , named_for = Vale of Tempe , image_skyline = Tempeskyline3.jpg , imagesize = 260px , image_caption = Tempe skyline as seen from Papago Park , image_flag = Tempe, Arizona official flag.png , seal_size = , image_map = File:Maricopa County Arizona Incorporated and Unincorporated areas Tempe Highlighted 0473000.svg , mapsize = 250px , map_caption = Location of Tempe in Maricopa County, Arizona , image_map1 = , mapsize1 = , map_caption1 = , pushpin_map = Arizona#USA , pushpin_map_caption = Location in Arizona##Location in the United States , pushpin_relief = 1 , coordinates = , subdivision_type = L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nevada
Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the List of U.S. states and territories by area, 7th-most extensive, the List of U.S. states and territories by population, 32nd-most populous, and the List of U.S. states and territories by population density, 9th-least densely populated of the U.S. states. Nearly three-quarters of Nevada's people live in Clark County, Nevada, Clark County, which contains the Las Vegas–Paradise, NV MSA, Las Vegas–Paradise metropolitan area, including three of the state's four largest incorporated cities. Nevada's capital is Carson City, Nevada, Carson City. Las Vegas is the largest city in the state. Nevada is officially known as the "Silver State" because of the importance of silver to its history and economy. It is also known as the "Battle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modified Mercalli Intensity Scale
The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the effects of an earthquake at a given location, distinguished from the earthquake's inherent force or strength as measured by seismic magnitude scales (such as the "" magnitude usually reported for an earthquake). While shaking is caused by the seismic energy released by an earthquake, earthquakes differ in how much of their energy is radiated as seismic waves. Deeper earthquakes also have less interaction with the surface, and their energy is spread out across a larger volume. Shaking intensity is localized, generally diminishing with distance from the earthquake's epicenter, but can be amplified in sedimentary basins and certain kinds of unconsolidated soils. Intensity scales empirically categorize the intensity of shaking based on the effect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Creepmeter
A creepmeter is an instrument that monitors the slow surface displacement of an active geologic fault in the Earth. Its function is to record the slow, aseismic creep between earthquakes. The measurement range of a creepmeter is usually limited to 10–30 mm. Approximately 40 creepmeters are in operation in California—most are operated by the United States Geological Survey (USGS), but nine are maintained by the University of Colorado The University of Colorado (CU) is a system of public universities in Colorado. It consists of four institutions: University of Colorado Boulder, University of Colorado Colorado Springs, University of Colorado Denver, and the University of Co .... References Structural geology Measuring instruments Seismology {{struct-geology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calipatria, California
Calipatria (portmanteau of ''California'' and ''Patria'', Spanish language, Spanish for "homeland") is a city in Imperial County, California, Imperial County, California. Calipatria is located north of El Centro, California, El Centro. It is part of the El Centro Metropolitan Area. The population was 6,515 at the 2020 census, down from 7,710 at the 2010 census, up from 7,289 at the 2000 census, including 4000 inmates at Calipatria State Prison. The community is located along California State Route 111, State Route 111. Geography Calipatria is located at . At an elevation of below sea level, Calipatria is the lowest elevation city in the western hemisphere. The city currently claims to have the "tallest flagpole (184 feet) where the flag flies at sea level" at , so their American flag will always fly above sea level. According to the Guinness Book of World Records, the Jeddah Flagpole holds the title of world's tallest, but it is entirely above sea level. According to th ... [...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] |
Accelerograph
An accelerograph can be referred to as a strong-motion instrument or seismograph, or simply an earthquake accelerometer. They are usually constructed as a self-contained box, which previously included a paper or film recorder (an analogue instrument) but now they often record directly on digital media and then the data is transmitted via the Internet. Accelerographs are useful for when the earthquake ground motion is so strong that it causes the more sensitive seismometers to go off-scale. There is an entire science of strong ground motion, that is dedicated to studying the shaking in the vicinity of earthquakes (roughly within about 100 km of the fault rupture). Accelerographs record the acceleration of the ground with respect to time. This recording is often called an accelerograms, strong-motion record or acceleration time-history. From this record strong-motion intensity measures (IMs, also called parameters) can be computed. The simplest of which is peak ground accelerat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USGS Shakemap - 1987 Superstition Hills Earthquake
The United States Geological Survey (USGS), formerly simply known as the 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's work spans the disciplines of biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility. The agency was founded on March 3, 1879. The USGS is a bureau of the United States Department of the Interior; it is that department's sole scientific agency. The USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, and Menlo Park, California. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous slogan, adopted on the occasion of its hundredth anniversa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Rupture
In seismology, surface rupture (or ground rupture, or ground displacement) is the visible offset of the ground surface when an earthquake rupture along a fault affects the Earth's surface. Surface rupture is opposed by buried rupture, where there is no displacement at ground level. This is a major risk to any structure that is built across a fault zone that may be active, in addition to any risk from ground shaking. Surface rupture entails vertical or horizontal movement, on either side of a ruptured fault. Surface rupture can affect large areas of land. __TOC__ Lack of surface rupture Not every earthquake results in surface rupture, particularly for smaller and deeper earthquakes. In some cases, however, the lack of surface effects is because the fault that moved does not reach the surface. For example, the 1994 Northridge earthquake had a moment magnitude of 6.7, caused major damage in the Los Angeles area, occurred at below the Earth's surface, but did not cause surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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