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Seismic Array
A seismic array is a system of linked seismometers arranged in a regular geometric pattern (cross, circle, rectangular etc.) to increase sensitivity to earthquake and explosion detection. A seismic array differs from a local network of seismic stations mainly by the techniques used for data analysis. The data from a seismic array is obtained using special digital signal processing techniques such as beamforming, which suppress noises and thus enhance the signal-to-noise ratio (SNR). The earliest seismic arrays were built in the 1950s in order to improve the detection of nuclear tests worldwide. Many of these deployed arrays were classified until the 1990s. Today they have become part of the International Monitoring System (IMS) as primary or auxiliary stations. Seismic arrays are not only used to monitor earthquakes and nuclear tests but also used as a tool for investigating nature and source regions of microseisms as well as locating and tracking volcanic tremor and analyzing comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seismometer
A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The output of such a device—formerly recorded on paper (see picture) or film, now recorded and processed digitally—is a seismogram. Such data is used to locate and characterize earthquakes, and to study the Earth's internal structure. Basic principles A simple seismometer, sensitive to up-down motions of the Earth, is like a weight hanging from a spring, both suspended from a frame that moves along with any motion detected. The relative motion between the weight (called the mass) and the frame provides a measurement of the vertical ground motion. A rotating drum is attached to the frame and a pen is attached to the weight, thus recording any ground motion in a seismogram. Any movement from the ground moves the frame. The mass tends not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectral Density Estimation
In statistical signal processing, the goal of spectral density estimation (SDE) or simply spectral estimation is to estimate the spectral density (also known as the power spectral density) of a signal from a sequence of time samples of the signal. Intuitively speaking, the spectral density characterizes the frequency content of the signal. One purpose of estimating the spectral density is to detect any periodicities in the data, by observing peaks at the frequencies corresponding to these periodicities. Some SDE techniques assume that a signal is composed of a limited (usually small) number of generating frequencies plus noise and seek to find the location and intensity of the generated frequencies. Others make no assumption on the number of components and seek to estimate the whole generating spectrum. Overview Spectrum analysis, also referred to as frequency domain analysis or spectral density estimation, is the technical process of decomposing a complex signal in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montana
Montana () is a U.S. state, state in the Mountain states, Mountain West List of regions of the United States#Census Bureau-designated regions and divisions, division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Provinces and territories of Canada, Canadian provinces of Alberta, British Columbia, and Saskatchewan to the north. It is the List of U.S. states and territories by area, fourth-largest state by area, the List of U.S. states and territories by population, eighth-least populous state, and the List of U.S. states and territories by population density, third-least densely populated state. Its state capital is Helena, Montana, Helena. The western half of Montana contains numerous mountain ranges, while the eastern half is characterized by western prairie terrain and badlands, with smaller mountain ranges found throughout the state. Montana has no official nickname but several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleseism
A teleseism is a tremor caused by an earthquake that is very far away (from the Ancient Greek τῆλε) from where it is recorded. According to the USGS, the term ''teleseismic'' refers to earthquakes that occur more than 1000 km from the measurement site. Small teleseismic events register only on sensitive seismometers in low background noise locations. In general, seismic waves from earthquakes of magnitude 5.0 and up can be recorded almost anywhere in the world with modern seismic instrumentation. References Seismology External links The Global CMT ProjectEarthquake GlossaryMagnitude 6.5 Tajikistan Earthquake recorded in basement at Guyot Hall {{Seismology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UKAEA
The United Kingdom Atomic Energy Authority is a UK government research organisation responsible for the development of fusion energy. It is an executive non-departmental public body of the Department for Business, Energy and Industrial Strategy (BEIS). The authority focuses on United Kingdom and European fusion energy research programmes at Culham in Oxfordshire, including the world's most powerful operating fusion device, the Joint European Torus (JET). The research aims to develop fusion power as a commercially viable, environmentally responsible energy source for the future. record59 megajoules of sustained fusion energy was demonstrated by scientists and engineers working on JET in December 2021. United Kingdom Atomic Energy Authority owns the Culham Science Centre and has a stake in the Harwell Campus, and is involved in the development of both sites as locations for science and innovation-based business. On its formation in 1954, the authority was responsible for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Resources Canada
Natural Resources Canada (NRCan; french: Ressources naturelles Canada; french: RNCan, label=none)Natural Resources Canada is the applied title under the Federal Identity Program; the legal title is Department of Natural Resources (). is the Structure of the Canadian federal government, department of the Government of Canada responsible for natural resources, energy, minerals and metals, forests, earth sciences, mapping, and remote sensing. It was formed in 1994 by amalgamating the Department of Energy, Mines and Resources with the Department of Forestry. Under the ''Constitution Act, 1867'', primary responsibility for natural resources falls to provincial governments, however, the federal government has jurisdiction over off-shore resources, trade and commerce in natural resources, statistics, international relations, and boundaries. The department administers federal legislation relating to natural resources, including energy, forests, minerals and metals. The department also co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northwest Territories
The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. At a land area of approximately and a 2016 census population of 41,790, it is the second-largest and the most populous of the three territories in Northern Canada. Its estimated population as of 2022 is 45,605. Yellowknife is the capital, most populous community, and only city in the territory; its population was 19,569 as of the 2016 census. It became the territorial capital in 1967, following recommendations by the Carrothers Commission. The Northwest Territories, a portion of the old North-Western Territory, entered the Canadian Confederation on July 15, 1870. Since then, the territory has been divided four times to create new provinces and territories or enlarge existing ones. Its current borders date from April 1, 1999, when t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yellowknife
Yellowknife (; Dogrib: ) is the capital, largest community, and only city in the Northwest Territories, Canada. It is on the northern shore of Great Slave Lake, about south of the Arctic Circle, on the west side of Yellowknife Bay near the outlet of the Yellowknife River. Yellowknife and its surrounding water bodies were named after a local Dene tribe, who were known as the "Copper Indians" or "Yellowknife Indians", today incorporated as the Yellowknives Dene First Nation. They traded tools made from copper deposits near the Arctic Coast. Its population, which is ethnically mixed, was 19,569 per the 2016 Canadian Census. Of the eleven official languages of the Northwest Territories, five are spoken in significant numbers in Yellowknife: Dene Suline, Dogrib, South and North Slavey, English, and French. In the Dogrib language, the city is known as ''Sǫǫ̀mbak’è'' (, "where the money is"). Modern Yellowknives members can be found in the adjoining, primarily Indigenou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peak Amplitude
The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of amplitude (see below), which are all functions of the magnitude of the differences between the variable's extreme values. In older texts, the phase of a periodic function is sometimes called the amplitude. Definitions Peak amplitude & semi-amplitude For symmetric periodic waves, like sine waves, square waves or triangle waves ''peak amplitude'' and ''semi amplitude'' are the same. Peak amplitude In audio system measurements, telecommunications and others where the measurand is a signal that swings above and below a reference value but is not sinusoidal, peak amplitude is often used. If the reference is zero, this is the maximum absolute value of the signal; if the reference is a mean value ( DC component), the peak amplitude is the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-correlation
In signal processing, cross-correlation is a measure of similarity of two series as a function of the displacement of one relative to the other. This is also known as a ''sliding dot product'' or ''sliding inner-product''. It is commonly used for searching a long signal for a shorter, known feature. It has applications in pattern recognition, single particle analysis, electron tomography, averaging, cryptanalysis, and neurophysiology. The cross-correlation is similar in nature to the convolution of two functions. In an autocorrelation, which is the cross-correlation of a signal with itself, there will always be a peak at a lag of zero, and its size will be the signal energy. In probability and statistics, the term ''cross-correlations'' refers to the correlations between the entries of two random vectors \mathbf and \mathbf, while the ''correlations'' of a random vector \mathbf are the correlations between the entries of \mathbf itself, those forming the correlation mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NORSAR
NORSAR or Norwegian Seismic Array was established in 1968 as part of the Norwegian- US agreement for the detection of earthquakes and nuclear explosions. Description Located at Kjeller, north of Oslo, NORSAR runs and maintains seismic arrays in Norway and it is the designated Norwegian National Data Centre for the Comprehensive Nuclear Test Ban Treaty. NORSAR conducts basic seismological research, develops software and provides consultancy for the petroleum industry. NORSAR was the first non-US site included in ARPANET in June 1973 with a connection via the Tanum Earth Station in Sweden to the Seismic Data Analysis Center (SDAC) in Virginia, United States. It was the connection point for ARPANET to spread to Peter Kirstein's research group at University College London (UCL) the following month in July 1973. Connecting through NORSAR, the Norwegian Defence Research Establishment, along with UCL and RSRE in Britain, were involved in testing TCP/IP. UCL provided a gateway be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plane Wave
In physics, a plane wave is a special case of wave or field: a physical quantity whose value, at any moment, is constant through any plane that is perpendicular to a fixed direction in space. For any position \vec x in space and any time t, the value of such a field can be written as :F(\vec x,t) = G(\vec x \cdot \vec n, t), where \vec n is a unit-length vector, and G(d,t) is a function that gives the field's value as dependent on only two real parameters: the time t, and the scalar-valued displacement d = \vec x \cdot \vec n of the point \vec x along the direction \vec n. The displacement is constant over each plane perpendicular to \vec n. The values of the field F may be scalars, vectors, or any other physical or mathematical quantity. They can be complex numbers, as in a complex exponential plane wave. When the values of F are vectors, the wave is said to be a longitudinal wave if the vectors are always collinear with the vector \vec n, and a transverse wave if t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
