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An earthquake warning system or earthquake alarm system is a system of accelerometers, seismometers, communication, computers, and alarms that is devised for rapidly notifying adjoining regions of a substantial earthquake once one begins. This is not the same as earthquake prediction, which is currently not capable of producing decisive event warnings.
An earthquake is caused by the release of stored elastic strain energy during rapid sliding along a fault. The sliding starts at some location and progresses away from the hypocenter in each direction along the fault surface. The speed of the progression of this fault tear is slower than, and distinct from the speed of the resultant pressure and shear waves, with the pressure wave traveling faster than the shear wave. The pressure waves are always smaller in amplitude than the damaging shear waves that are the most destructive to structures, particularly buildings that have a resonant period similar to those of the radiated waves. Typically, these buildings are around eight floors in height. These waves will be strongest at the ends of the slippage, and may project destructive waves well beyond the fault failure. The intensity of such remote effects are highly dependent upon local soils conditions within the region and these effects are considered in constructing a model of the region that determines appropriate responses to specific events.
Such systems are currently implemented to determine appropriate real-time response to an event by the train operator in urban rail systems such as BART (Bay Area Rapid Transit) and LA Metro. [1] The appropriate response is dependent on the warning time, the local right-of-way conditions and the current speed of the train.
As of 2024, China, Japan, Taiwan, South Korea and Israel have comprehensive, nationwide earthquake early warning systems. Other countries and regions have limited deployment of earthquake warning systems, including Mexico (the Mexican Seismic Alert System covers areas of central and southern Mexico including Mexico City and Oaxaca), limited regions of Romania (the Basarab bridge in Bucharest), and parts of the United States. The earliest automated earthquake pre-detection systems were installed in the 1990s; for instance, in California, the Calistoga fire station's system which automatically triggers a citywide siren to alert the entire area's residents of an earthquake. [3] Some California fire departments use their warning systems to automatically open overhead doors of fire stations before the earthquake can disable them. While many of these efforts are governmental, several private companies also manufacture earthquake early warning systems to protect infrastructure such as elevators, gas lines and fire stations.
In 2009, an early warning system called ShakeAlarm was installed and commissioned in Vancouver, British Columbia, Canada. It was placed to protect a piece of critical transportation infrastructure called the George Massey Tunnel, which connects the north and south banks of the Fraser River. In this application the system automatically closes the gates at the tunnel entrances if there is a dangerous seismic event inbound. [4] The success and the reliability of the system was such that as of 2015 there have been several additional installations on the west coast of Canada and the United States, and there are more being planned.
The earliest earthquake warning system in China was built in the 1990s. [5] The devastation of the 2008 Sichuan earthquake stimulated China's investment in nationwide earthquake early warning systems (EEWS). Large amounts of monitoring stations, sensors, and analytic systems were installed to improve the accuracy, responsiveness, and comprehensiveness of the earthquake data. In June 2019, the Chengdu Hi-Tech Disaster Reduction Institution, part of the national EEWS system, successfully warned various townships of a 6.0M earthquake 10-27 seconds before the shockwave arrived. [6] In 2023, China Earthquake Administration announced that the national EEWS was completed, with 150,000 monitoring stations, managed by three national centers, 31 provincial centers, 173 prefectural and municipal centers. It's the largest seismic network in the world. [5]
Japan's Earthquake Early Warning system was put to practical use in 2006. The system that warns the general public was installed on October 1, 2007. [7] [8] It was modeled partly on the Urgent Earthquake Detection and Alarm System (UrEDAS ) of Japan Railways, which was designed to enable automatic braking of bullet trains. [9]
Gravimetric data from the 2011 Tōhoku earthquake has been used to create a model for increased warning time compared to seismic models, as gravity fields travel at the speed of light, much faster than seismic waves. [10]
The Mexican Seismic Alert System, otherwise known as SASMEX, began operations in 1991 and began publicly issuing alerts in 1993. It is funded by the Mexico City government, with financial contributions from several states that receive the alert. Initially serving Mexico City with twelve sensors, the system now has 97 sensors and is designed to protect life and property in several central and southern Mexican states.
The United States Geological Survey (USGS) began research and development of an early warning system for the West Coast of the United States in August 2006, and the system became demonstrable in August 2009. [11] Following various developmental phases, version 2.0 went live during the fall of 2018, allowing the "sufficiently functional and tested" system to begin Phase 1 of alerting California, Oregon and Washington. [12]
Even though ShakeAlert could alert the public beginning September 28, 2018, the messages themselves could not be distributed until the various private and public distribution partners had completed mobile apps and made changes to various emergency alerting systems. The first publicly available alerting system was the ShakeAlertLA app, released on New Year's Eve 2018 (although it only alerted for shaking in the Los Angeles area). [13] On October 17, 2019, Cal OES announced a statewide rollout of the alert distribution system in California, using mobile apps and the Wireless Emergency Alerts (WEA) system. [14] [15] [16] California refers to their system as the California Earthquake Early Warning System. A statewide alert distribution system was rolled out in Oregon on March 11, 2021 [17] and in Washington on May 4, 2021, completing the alert system for the West Coast. [18] [19]
In January 2013, Francesco Finazzi of the University of Bergamo started the Earthquake Network research project which aims at developing and maintaining a crowdsourced earthquake warning system based on smartphone networks. [2] [20] Smartphones are used to detect the ground shaking induced by an earthquake and a warning is issued as soon as an earthquake is detected. People living at a further distance from the epicenter and the detection point may be alerted before they are reached by the damaging waves of the earthquake. People can take part in the project by installing the Android application "Earthquake Network" on their smart phones. The app requires the phone to receive the alerts.
In February 2016, the Berkeley Seismological Laboratory at University of California, Berkeley (UC Berkeley) released the MyShake mobile app. The app uses accelerometers in phones that are stationary and connected to a power supply to record shaking and relay that information back to the laboratory. [21] [22] The system issues automated warnings of earthquakes of magnitude 4.5 or greater. [22] UC Berkeley released a Japanese-language version of the app in May 2016. [23] By December 2016, the app had captured nearly 400 earthquakes worldwide. [24]
On August 11, 2020, Google announced that its Android operating system would begin using accelerometers in devices to detect earthquakes (and send the data to the company's "earthquake detection server"). As millions of phones operate on Android, this may result in the world's largest earthquake detection network. [25]
Initially, the system only collected earthquake data and did not issue alerts (except for on the West Coast of the United States, where it provided alerts issued by the USGS's ShakeAlert system and not from Google's own detection system). Data collected by Android devices was only used to provide fast information on the earthquake via Google Search, although it was always planned to issue alerts for many other areas based on Google's detection capabilities in the future. [25] On April 28, 2021, Google announced the rollout of the alert system to Greece and New Zealand, the first countries to receive alerts based on Google's own detection capabilities. [26] Google's alerts were extended to Turkey, the Philippines, Kazakhstan, Kyrgyz Republic, Tajikistan, Turkmenistan and Uzbekistan in June 2021. [27]
On August 11, 2020, Linux Foundation, IBM and Grillo announced the first fully open-source earthquake early-warning system, featuring instructions for a low-cost seismometer, cloud-hosted detection system, dashboard and mobile app. [28] This project is supported by USAID, the Clinton Foundation and Arrow Electronics. Smartphone-based earthquake early-warning systems are dependent on a dense network of users near the earthquake rupture zone, whereas OpenEEW has focused instead on providing affordable devices that can be deployed in remote regions close to where earthquakes can begin. All components of this system are open source and available on the project's GitHub repositories.
Social networking sites such as Twitter and Facebook play a significant role during natural disasters. [29] The United States Geological Survey (USGS) has investigated collaboration with the social networking site Twitter to allow for more rapid construction of ShakeMaps. [30] [31]
An earthquake – also called a quake, tremor, or temblor – is the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume.
Seismology is the scientific study of earthquakes and the generation and propagation of elastic waves through the Earth or other planetary bodies. It also includes studies of earthquake environmental effects such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, glacial, fluvial, oceanic microseism, atmospheric, and artificial processes such as explosions and human activities. A related field that uses geology to infer information regarding past earthquakes is paleoseismology. A recording of Earth motion as a function of time, created by a seismograph is called a seismogram. A seismologist is a scientist works in basic or applied seismology.
Hiroo Kanamori is a Japanese seismologist who has made fundamental contributions to understanding the physics of earthquakes and the tectonic processes that cause them.
The Pacific Northwest Seismic Network, or PNSN, collects and studies ground motions from about 400 seismometers in the U.S. states of Oregon and Washington. PNSN monitors volcanic and tectonic activity, gives advice and information to the public and policy makers, and works to mitigate earthquake hazard.
A tsunami warning system (TWS) is used to detect tsunamis in advance and issue the warnings to prevent loss of life and damage to property. It is made up of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of the coastal areas. There are two distinct types of tsunami warning systems: international and regional. When operating, seismic alerts are used to instigate the watches and warnings; then, data from observed sea level height are used to verify the existence of a tsunami. Other systems have been proposed to augment the warning procedures; for example, it has been suggested that the duration and frequency content of t-wave energy is indicative of an earthquake's tsunami potential.
The Pacific Tsunami Warning Center (PTWC), located on Ford Island, Hawaii, is one of two tsunami warning centers in the United States, covering Hawaii, Guam, American Samoa and the Northern Mariana Islands in the Pacific, as well as Puerto Rico, the U.S. Virgin Islands and the British Virgin Islands in the Caribbean Sea. Other parts of the United States are covered by the National Tsunami Warning Center.
Seismic magnitude scales are used to describe the overall strength or "size" of an earthquake. These are distinguished from seismic intensity scales that categorize the intensity or severity of ground shaking (quaking) caused by an earthquake at a given location. Magnitudes are usually determined from measurements of an earthquake's seismic waves as recorded on a seismogram. Magnitude scales vary based on what aspect of the seismic waves are measured and how they are measured. Different magnitude scales are necessary because of differences in earthquakes, the information available, and the purposes for which the magnitudes are used.
In Japan, the Earthquake Early Warning (EEW) is a warning issued when an earthquake is detected by multiple seismometers. These warnings are primarily issued by the Japan Meteorological Agency (JMA), with guidance on how to react to them.
The April 2011 Miyagi earthquake occurred off the coast of Miyagi Prefecture, approximately 66 kilometres (41 mi) east of Sendai, Japan. The Mw7.1 thrust earthquake was classified as an aftershock of the March 11 Tōhoku earthquake, and occurred at 23:32 JST (14:32 UTC) on Thursday, 7 April 2011.
A potent magnitude 6.6 Mw intraplate aftershock occurred at 17:16 JST (08:16 UTC) on 11 April, in the Hamadōri region of Fukushima, Japan. With a shallow focus of 13 km (8.1 mi), the earthquake was centred inland about 36 km (22 mi) west of Iwaki, causing widespread strong to locally severe shaking. It was one of many aftershocks to follow the 11 March Tōhoku earthquake, and the strongest to have its epicentre located inland.
The 2011 Guerrero earthquake struck with a moment magnitude of 5.7 in southern Mexico at 08:24 local time on 5 May. It was positioned west of Ometepec, Guerrero, with a focal depth of 24 km (14.9 mi), and was lightly felt in many adjacent areas.
The 2014 South Napa earthquake occurred in the North San Francisco Bay Area on August 24 at 03:20:44 Pacific Daylight Time. At 6.0 on the moment magnitude scale and with a maximum Mercalli intensity of VIII (Severe), the event was the largest in the San Francisco Bay Area since the 1989 Loma Prieta earthquake. The epicenter of the earthquake was located to the south of Napa and to the northwest of American Canyon on the West Napa Fault.
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".
ShakeAlarm is an on-site earthquake early warning system (EEWS) developed by Weir-Jones Engineering Consultants in Vancouver, British Columbia. The system functions by detecting and identifying fast moving P-waves that arrive before the slower and damaging S-waves generated from the hypocenter of an earthquake. Once ShakeAlarm has identified a candidate P-wave it will determine in less than 500 milliseconds if the following S-wave will be strong enough to be dangerous. Once the determination has been reached that an inbound S-wave might exceed acceptable levels the system can trigger the structured shutdown of critical processes - gas, electricity and water services - and can also be used for opening of fire bay doors, SMS warnings to the general population and a variety of other services to be activated before the S-wave's (shaking) impact. ShakeAlarm represents a streamlined site specific application of technology and ideas that Japan has been working with for some time on a nationwide deployment level in the form of a network.
ShakeAlert is an earthquake early warning system (EEW) in the United States, developed and operated by the United States Geological Survey (USGS) and its partners. As of 2021, the system issues alerts for the country's West Coast. It is expected that the system will be expanded to other seismically active areas of the United States in the future.
Earthquake Network research project that aims to develop and maintain a crowdsourced smartphone-based earthquake warning system at a global level. The system uses the on-board accelerometers in privately-owned smartphones of volunteer participants to detect earthquake waves. When it detects an earthquake, it issues an earthquake warning to alert people who the damaging waves of the earthquake have not yet reached.
The Advanced National Seismic System (ANSS) is a collaboration of the U.S. Geological Survey (USGS) and regional, state, and academic partners that collects and analyzes data on significant earthquakes to provide near real-time information to emergency responders and officials, the news media, and the public. Such information is used to anticipate the likely severity and extent of damage, and to guide decisions on the responses needed.
The 2019 Ridgecrest earthquakes of July 4 and 5 occurred north and northeast of the town of Ridgecrest, California located in Kern County and west of Searles Valley. They included three initial main shocks of Mw magnitudes 6.4, 5.4, and 7.1, and many perceptible aftershocks, mainly within the area of the Naval Air Weapons Station China Lake. Eleven months later, a Mw 5.5 aftershock took place to the east of Ridgecrest. The first main shock occurred on Thursday, July 4 at 10:33 a.m. PDT, approximately 18 km (11.2 mi) ENE of Ridgecrest, and 13 km (8.1 mi) WSW of Trona, on a previously unnoticed NE-SW trending fault where it intersects the NW-SE trending Little Lake Fault Zone. This quake was preceded by several smaller earthquakes, and was followed by more than 1,400 detected aftershocks. The M 5.4 and M 7.1 quakes struck on Friday, July 5 at 4:08 a.m. and 8:19 p.m. PDT approximately 10 km (6 miles) to the northwest. The latter, now considered the mainshock, was the most powerful earthquake to occur in the state in 20 years. Subsequent aftershocks extended approximately 50 km (~30 miles) along the Little Lake Fault Zone.
Elizabeth Scott Cochran is a seismologist known for her work on early warning systems for earthquakes and human-induced earthquakes.
On December 20, 2022, a magnitude 6.4 earthquake struck Ferndale, California in Humboldt County, United States at 10:34:25 UTC, or 2:34 a.m. PST.
UC Berkeley scientists today are releasing a free Android app that taps a smartphone's ability to record ground shaking from an earthquake, with the goal of creating a worldwide seismic detection network that could eventually warn users of impending jolts from nearby quakes.
