An earthquake warning system or earthquake early warning system is a system of accelerometers, seismometers, communication, computers, and alarms that is devised for notifying adjoining regions of a substantial earthquake while it is in progress. This is not the same as earthquake prediction, which is currently incapable 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 generate an abrupt shock. The shear waves generate periodic motion (at about 1 Hz) that is the most destructive to structures, particularly buildings that have a similar resonant period. 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. The appropriate response is dependent on the warning time, the local right-of-way conditions and the current speed of the train.
As of 2016, Japan and Taiwan 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.
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This course presents the classical and new approaches required to study the source mechanisms of earthquakes, combining theory and observations in a unified methodology, with a key focus on the mechan
Dynamics loads on structures, equations of motion of linear single- and multiple-degree-of freedom systems; free an forced vibrations; damping in structures: modal superposition and response history a
This course deals with the main aspects of seismic design and assessment of buildings including conceptual design. It covers different structural design and evaluation philosophies for new and existin
The epicenter (ˈɛpɪˌsɛntər), epicentre, or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Before the instrumental period of earthquake observation, the epicenter was thought to be the location where the greatest damage occurred, but the subsurface fault rupture may be long and spread surface damage across the entire rupture zone. As an example, in the magnitude 7.
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that 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.
Covers risk analysis and management related to earthquakes, focusing on the 2015 Nepal earthquake.
Explores magnetic sensors like fluxgate and reed relay, emphasizing their applications in measuring weak magnetic fields and as on/off sensors based on magnetic attraction.
Explores the effects of earthquakes and earthquake damage to structures.
Field observations and comprehensive life-cycle building assessment suggest that buildings designed according to today's seismic standards meet the life-safety requirement. However, they are prone to economic losses due to repairs in the aftermath of earth ...
EPFL2022
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Image information about the state of a building after an earthquake, which can be collected without endangering the post-earthquake reconnaissance activities, can be used to reduce uncertainties in response predictions for future seismic events. This paper ...
Springer2024
The seismic assessment of existing unreinforced masonry buildings to determine their vulnerability is a critical issue for all earthquake-prone locations, and Switzerland is no exception. As a result, a thorough examination of the behaviour of masonry stru ...