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A seismic scale is used to measure and compare the relative severity of earthquakes. An earthquake is a phenomenon that results from the sudden release of stored energy in the Earths crust that creates seismic waves. ...
Two fundamentally different but equally important types of scales are commonly used by seismologists to describe earthquakes. The original force or energy of an earthquake is measured on a magnitude scale, while the intensity of shaking occurring at any given point on the Earth's surface is measured on an intensity scale.
- See the table of seismic scales at the end of this article.
Severity The severity of an earthquake is described by both magnitude and intensity. These two frequently-confused terms both refer to different, but related, observations. Magnitude, usually expressed as an Arabic numeral, characterizes the size of an earthquake by measuring indirectly the energy released. By contrast, intensity indicates the local effects and potential for damage produced by an earthquake on the Earth's surface as it affects humans, animals, structures, and natural objects such as bodies of water. Intensities are usually expressed in roman numerals, each representing the severity of the shaking resulting from an earthquake. Any given earthquake can be described by only one magnitude, but many intensities since the earthquake effects vary with circumstances such as distance from the epicenter and local soil conditions. Arabic numerals (also called Hindu numerals or Hindu-Arabic numerals) are by far the most common form of symbolism used to represent numbers. ...
A body of water is any significant natural pool of water such as an ocean, a lake, or a river, covering the Earth or another planet. ...
Roman numerals are a numeral system originating in ancient Rome, adapted from Etruscan numerals. ...
The epicenter is directly above the earthquakes focus. ...
Charles Richter, the creator of the Richter magnitude scale, distinguished intensity and magnitude as follows: "I like to use the analogy with radio transmissions. It applies in seismology because seismographs, or the receivers, record the waves of elastic disturbance, or radio waves, that are radiated from the earthquake source, or the broadcasting station. Magnitude can be compared to the power output in kilowatts of a broadcasting station. Local intensity on the Mercalli scale is then comparable to the signal strength on a receiver at a given locality; in effect, the quality of the signal. Intensity, like signal strength, will generally fall off with distance from the source, although it also depends on the local conditions and the pathway from the source to the point." Charles Francis Richter (April 26, 1900 – April 20, 1985), was an American seismologist, born in Hamilton, Ohio. ...
The Richter magnitude test scale (or more correctly local magnitude ML scale) assigns a single number to quantify the size of an earthquake. ...
In communications, transmission is the act of transmitting electrical messages (and the associated phenonomena of radiant energy that pass through media). ...
Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...
Seismographs (in Greek seismos = earthquake and graphein = write) are used by seismologists to record seismic waves. ...
In radio terminology, a receiver is an electronic circuit that receives a radio signal from an antenna and decodes the signal for use as sound, pictures, navigational-position information, etc. ...
To meet Wikipedias quality standards and appeal to a wider international audience, this article may require cleanup. ...
The kilowatt (symbol: kW) is a unit for measuring power, equal to one thousand watts. ...
To meet Wikipedias quality standards and appeal to a wider international audience, this article may require cleanup. ...
The Mercalli Intensity Scale is a scale used to classify the intensity of an earthquake by examining its effects on people and structures at the Earths surface. ...
The term locality has different meanings in different disciplines: Geography In geography, a locality is a place. ...
Seismic intensity scales The first simple classification of earthquake intensity was devised by Domenico Pignataro in the 1780s. However, the first recognisable intensity scale in the modern sense of the word was drawn up by P.N.G. Egen in 1828; it was ahead of its time. The first widely adopted intensity scale, the Rossi-Forel scale, was introduced in the late 19th century. Since then numerous intensity scales have been developed and are used in different parts of the world: the scale currently used in the United States is the Modified Mercalli scale (MM), while the European Macroseismic Scale is used in Europe, the Shindo scale is used in Japan, and the MSK-64 scale is used in India, Israel, Russia and throughout the CIS. Most of these scales have twelve degrees of intensity, which are roughly equivalent to one another in values but vary in the degree of sophistication employed in their formulation. The Rossi-Forel scale was one of the first seismic scales to reflect earthquake intensities. ...
The Mercalli intensity scale is a scale used for measuring the intensity of earthquake. ...
The European Macroseismic Scale, most recently updated in 1998, is the basis for evaluation of seismic intensity in European countries. ...
Motto: In varietate concordia2 Anthem: Ode to Joy (orchestral) Capital Brussels (de facto) Largest city London Official languages 23 Member states 27 Presidencies - Commission José Manuel Barroso - Parliament Hans-Gert Pöttering - Council Frank-Walter Steinmeier - European Council Germany Formation - Treaty of Rome 25 March 1957 - Maastricht Treaty 7 February...
The Japan Meteorological Agency seismic intensity scale (震度 shindo) is a measure used in Japan to indicate the strength of earthquakes. ...
The Medvedev-Sponheuer-Karnik scale (MSK-64) is a macroseismic intensity scale. ...
Headquarters Minsk, Belarus Member states 11 member states 1 associate member Working language Russian Executive Secretary Vladimir Rushailo Formation December 21, 1991 Official website http://cis. ...
Magnitude scales The first attempt to qualitatively define a single, absolute value to describe the size of earthquakes was the magnitude scale (the name being taking from similarly formulated scales used to represent the brightness of stars).
Local magnitude scale -
The local magnitude scale (ML), also popularly known as the Richter Scale, is a quantitative logarithmic scale. In the 1930s, California seismologist Charles F. Richter devised a simple numerical scale to describe the relative sizes of earthquakes in Southern California. The name "Richter Scale" was coined by journalists and is not generally used by seismologists in technical literature. ML is obtained by measuring the maximum amplitude of a recording on a Wood-Anderson torsion seismometer (or one calibrated to it) at a distance of 600 km from the earthquake. Other more recent magnitude measurements include: body wave magnitude (mb), surface wave magnitude (Ms), and duration magnitude (MD). Each of these is scaled to give values similar to those given by the local magnitude scale; but because each is based on a measurement of one part of the seismogram, they do not measure the overall power of the source and can be negatively affected by saturation at higher magnitude values—meaning that they fail to report higher magnitude values for larger events. This problem sets in at around magnitude 6 for local magnitude; surface-wave magnitude saturates above 8. Despite the limitations of older magnitude scales, they are still in wide use, as they can be calculated rapidly, catalogues of them dating back many years are available, and the public is familiar with them. The Richter magnitude test scale (or more correctly local magnitude ML scale) assigns a single number to quantify the size of an earthquake. ...
The 1930s (years from 1930-1939) were described as an abrupt shift to more radical and conservative lifestyles, as countries were struggling to find a solution to the Great Depression, also known in Europe as the World Depression. ...
Charles Francis Richter (April 26, 1900 – April 20, 1985), was an American seismologist, born in Hamilton, Ohio. ...
The Richter magnitude test scale (or more correctly local magnitude ML scale) assigns a single number to quantify the size of an earthquake. ...
Seismometer (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. ...
. . A seismic wave is a wave that travels through the Earth, often as the result of an earthquake or explosion. ...
// In physics, a surface wave can refer to a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. ...
A seismogram is a graph output by a seismograph. ...
Moment magnitude scale -
Because of the limitations of the magnitude scales, a new, more uniformly applicable extension of them, known as moment magnitude (MW), was developed. In particular, for very large earthquakes moment magnitude gives the most reliable estimate of earthquake size. This is because seismic moment is derived from the concept of moment in physics and therefore provides clues to the physical size of an earthquake—the size of fault rupture and accompanying displacement and length of slippage — as well as the amount of energy released. So while seismic moment, too, is calculated from seismograms, it can also be obtained by working backwards from geologic estimates of the size of the fault rupture and displacement. The values of moments for different earthquakes range over several orders of magnitude, and because they are not influenced by variables such as local circumstances, the results obtained make it easy to objectively compare the sizes of different earthquakes. These characteristics, plus the seismic moment's immunity to saturation at higher magnitudes and compatibility with other magnitude scales, led Tom Hanks and Hiroo Kanamori to introduce in 1979 the moment magnitude (MW) scale for representing the absolute size of earthquakes. The moment magnitude scale was introduced in 1979 by Tom Hanks and Hiroo Kanamori as a successor to the Richter scale and is used by seismologists to compare the energy released by earthquakes. ...
In physics, the moment of force (often just moment, though there are other quantities of that name such as moment of inertia) is a quantity that represents the magnitude of force applied to a rotational system at a distance from the axis of rotation. ...
A seismogram is a graph output by a seismograph. ...
Tom Hanks is a seismologist who has the same name as the actor Tom Hanks. ...
Hiroo Kanamori (金森 åšé›„ Kanamori Hiroo; October 17, 1936—) is a seismologist who has made fundamental contributions to understanding the physics of earthquakes and the tectonic processes that cause them. ...
The moment magnitude scale (a successor to the Richter Scale), was introduced in 1979 by Tom Hanks and Hiroo Kanamori and is used by seismologists to compare the energy released by earthquakes. ...
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