Which scale is used to measure the intensity, not the magnitude, of earthquakes?
"1968 Dasht-e Bayaz and Ferdows earthquakes The Dasht-e Bayaz and Ferdows earthquakes occurred in Dashte Bayaz, Kakhk and Ferdows, Iran in late August and early September 1968. The mainshock measured 7.4 on the moment magnitude scale and had a maximum perceived intensity of X (""Extreme"") on the Mercalli intensity scale. Damage was heavy in the affected areas with thousands of lives lost in the first event and many hundreds more in the second strong event. The Iranian plateau is confined by the Turan platform in the north and the Zagros fold and thrust belt and Makran Trench in the south."
"Seismic intensity scales Seismic intensity scales categorize the intensity or severity of ground shaking (quaking) at a given location, such as resulting from an earthquake. They are distinguished from seismic magnitude scales, which measure the magnitude or overall strength of an earthquake. Intensity scales are based on the observed effects of the shaking, such as the degree to which people or animals were alarmed, and the extent and severity of damage to different kinds of structures or natural features. The maximal intensity observed, and the extent of the area where shaking was felt (see isosiesmal map, below), can be used"
"Seismic magnitude scales 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 on the type and component of the seismic waves measured and the calculations used. Different magnitude scales are necessary because of differences in earthquakes, and in the purposes for which magnitudes are used. The Earth's crust is stressed"
"Richter magnitude scale The so-called Richter magnitude scale – more accurately, ""Richter's magnitude scale"", or just ""Richter magnitude"" – for measuring the strength (""size"") of earthquakes refers to the original ""magnitude scale"" developed by Charles F. Richter and presented in his landmark 1935 paper, and later revised and renamed the Local magnitude scale, denoted as ""ML"" or ""M"". Because of various shortcomings of the ML scale most seismological authorities now use other scales, such as the moment magnitude scale (), to report earthquake magnitudes, but much of the news media still refers to these as ""Richter"" magnitudes. All magnitude scales"
"Environmental Seismic Intensity scale The Environmental Seismic Intensity scale (ESI 2007) is a seismic scale used for measuring the intensity of an earthquake on the basis of the effects of the earthquake on the natural environment (Earthquake Environmental Effects). The international effort to develop a new scale of macroseismic intensity that would focus exclusively on environmental effects of earthquakes began in the early 1990s and was sponsored by the International Union for Quaternary Research (INQUA). After the final draft of the scale was approved by INQUA at its XVII Congress in Cairns, Australia, in 2007, the scale became officially known"
"both scales. Unlike other scales, the moment magnitude scale does not saturate at the upper end; there is no upper limit to the possible measurable magnitudes. However, this has the side-effect that the scales diverge for smaller earthquakes. Various ways of determining moment magnitude have been developed, and several subtypes of the scale can be used to indicate the basis used. Moment magnitude scale The moment magnitude scale (MMS; denoted as M"" or M"") is one of many seismic magnitude scales used to measure the size of earthquakes. The scale was developed in the 1970s to succeed the 1930s-era Richter"
"the International Association of Seismology and Physics of the Earth's Interior (IASPEI) has standardized the measurement procedures and equations for the principal magnitude scales, , , , and . The first scale for measuring earthquake magnitudes, developed in 1935 by Charles F. Richter and popularly known as the ""Richter"" scale, is actually the , label ML or M. Richter established two features now common to all magnitude scales. First, the scale is logarithmic, so that each unit represents a ten-fold increase in the ""amplitude"" of the seismic waves. As the energy of a wave is 10 times its amplitude, each"
"Moment magnitude scale The moment magnitude scale (MMS; denoted as M"" or M"") is one of many seismic magnitude scales used to measure the size of earthquakes. The scale was developed in the 1970s to succeed the 1930s-era Richter magnitude scale (""M""). Even though the formulas are different, the new scale was designed to produce magnitude values for a given earthquake similar to those produced by the older one. Under suitable assumptions, as with the Richter magnitude scale, an increase of one step on this logarithmic scale corresponds to a 10 (about 32) times increase in the amount of energy"
"for measuring earthquake magnitudes was developed by Charles F. Richter in 1935. Subsequent scales (see seismic magnitude scales) have retained a key feature, where each unit represents a ten-fold difference in the amplitude of the ground shaking, and a 32-fold difference in energy. Subsequent scales are also adjusted to have approximately the same numeric value within the limits of the scale. Although the mass media commonly reports earthquake magnitudes as ""Richter magnitude"" or ""Richter scale"", standard practice by most seismological authorities is to express an earthquake's strength on the moment magnitude scale, which is based on the actual energy released"
"it is based on, is not measured routinely for smaller quakes. For example, the United States Geological Survey does not use this scale for earthquakes with a magnitude of less than 3.5, which includes the great majority of quakes. Current practice in official earthquake reports is to adopt moment magnitude as the preferred magnitude, i.e., is the official magnitude reported whenever it can be computed. Because seismic moment (, the quantity needed to compute ) is not measured if the earthquake is too small, the reported magnitude for earthquakes smaller than is often Richter's . Popular press reports most often"
"scale has been applied to modern, historical and paleoearthquakes in the frame of the INQUA TERPRO Commission on Paleoseismology and Active tectonics. It is now available in ten different languages. Environmental Seismic Intensity scale The Environmental Seismic Intensity scale (ESI 2007) is a seismic scale used for measuring the intensity of an earthquake on the basis of the effects of the earthquake on the natural environment (Earthquake Environmental Effects). The international effort to develop a new scale of macroseismic intensity that would focus exclusively on environmental effects of earthquakes began in the early 1990s and was sponsored by the International"
"indirectly and incompletely reflect the force of an earthquake, involve other factors, and are generally limited in some respect of magnitude, focal depth, or distance. The ""moment magnitude scale"" – Mw or M – developed by and , is based on an earthquake's ""seismic moment"", M, a measure of how much work an earthquake does in sliding one patch of rock past another patch of rock. Seismic moment is measured in Newton-meters (Nm or Nm) in the SI system of measurement, or dyne-centimeters (dyn-cm) in the older CGS system. In the simplest case the moment can be calculated knowing only"
"Surface wave magnitude The surface wave magnitude (formula_1) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the Earth. It is currently used in People's Republic of China as a national standard(GB 17740-1999) for categorising earthquakes. Surface wave magnitude was initially developed in the 1950s by the same researchers who developed the local magnitude scale M in order to improve resolution on larger earthquakes: Recorded magnitudes of earthquakes during that time, commonly attributed to Richter,"
"for the event was based on a calculation that requires only about 3 minutes. This calculation is, in turn, based on the maximum amplitude of the seismic wave. The amplitude of the seismic wave is measured using the , which is similar to Richter magnitude scale. However, these scales ""saturate"" for earthquakes that are above a certain magnitude (magnitude 8 on the JMA scale); that is, in the case of very large earthquakes, the scales' values change little despite large differences in the earthquakes' energy. This resulted in an underestimation of the tsunami's height in initial reports. Problems in issuing"
"the area. 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. Seismic intensity scales Seismic intensity scales categorize the intensity or severity of ground shaking (quaking) at a given location, such as resulting from"
"the same thing is that at different distances, for different hypocentral depths, and for different earthquake sizes, the amplitudes of different types of elastic waves must be measured. formula_2 is the scale used for the majority of earthquakes reported (tens of thousands) by local and regional seismological observatories. For large earthquakes worldwide, the moment magnitude scale (MMS) is most common, although formula_3 is also reported frequently. The seismic moment, formula_12, is proportional to the area of the rupture times the average slip that took place in the earthquake, thus it measures the physical size of the event. formula_5 is derived"
"to the millions of tonnes of rock removed in the mining process. The instrumental scales used to describe the size of an earthquake began with the Richter magnitude scale in the 1930s. It is a relatively simple measurement of an event's amplitude, and its use has become minimal in the 21st century. Seismic waves travel through the Earth's interior and can be recorded by seismometers at great distances. The surface wave magnitude was developed in the 1950s as a means to measure remote earthquakes and to improve the accuracy for larger events. The moment magnitude scale measures the amplitude of"
"Using the Modified Mercalli Intensity scale, earthquakes are categorized descriptively on a scale from I (not felt) to XII (total destruction) based on observed effects of the seismic event. While the ground accelerations of these two types of events are similar, the resulting intensity of intraplate earthquakes is significantly greater than that of interplate earthquakes due to the greater energy release (stress drop) across intraplate faults. Stress drop is a measure of the stress across a fault before and after an earthquake rupture. While intraplate and interplate earthquakes obey similar length proportional scaling laws, interplate earthquakes exhibit stress drop values"
"design basis earthquake ground motion (DBEGM) is often defined in terms of PGA. Unlike the Richter and moment magnitude scales, it is not a measure of the total energy (magnitude, or size) of an earthquake, but rather of how hard the earth shakes at a given geographic point. The Mercalli intensity scale uses personal reports and observations to measure earthquake intensity but PGA is measured by instruments, such as accelerographs. It can be correlated to macroseismic intensities on the Mercalli scale but these correlations are associated with large uncertainty. See also seismic scale. The peak horizontal acceleration (PHA) is the"
"degrees. formula_40 is mainly between 5 and 8. The Tsumura empirical formula: Where formula_42 is the total duration of oscillation in seconds. formula_40 is mainly between 3 and 5. The Tsuboi, University of Tokyo, empirical formula: Where formula_31 is the amplitude in micrometers. Richter magnitude scale The so-called Richter magnitude scale – more accurately, ""Richter's magnitude scale"", or just ""Richter magnitude"" – for measuring the strength (""size"") of earthquakes refers to the original ""magnitude scale"" developed by Charles F. Richter and presented in his landmark 1935 paper, and later revised and renamed the Local magnitude scale, denoted as ""ML"" or"
"magnitude before the quake's exact location is known. Magnitude scales generally are based on instrumental measurement of some aspect of the seismic wave as recorded on a seismogram. Where such records do not exist, magnitudes can be estimated from reports of the macroseismic events such as described by intensity scales. One approach for doing this (developed by Beno Gutenberg and Charles Richter in 1942) relates the maximum intensity observed (presumably this is over the epicenter), denoted ""I"" (capital I, subscripted zero), to the magnitude. It has been recommended that magnitudes calculated on this basis be labeled ""M(I)"", but are sometimes"
"waves travel through. Determination of an earthquake's magnitude generally involves identifying specific kinds of these waves on a seismogram, and then measuring one or more characteristics of a wave, such as its timing, orientation, amplitude, frequency, or duration. Additional adjustments are made for distance, kind of crust, and the characteristics of the seismograph that recorded the seismogram. The various magnitude scales represent different ways of deriving magnitude from such information as is available. All magnitude scales retain the logarithmic scale as devised by Charles Richter, and are adjusted so the mid-range approximately correlates with the original ""Richter"" scale. Since 2005"
"Intensity Scale (ITIS-2012), intended to match as closely as possible to the modified ESI2007 and EMS earthquake intensity scales. The first scale that genuinely calculated a magnitude for a tsunami, rather than an intensity at a particular location was the ML scale proposed by Murty & Loomis based on the potential energy. Difficulties in calculating the potential energy of the tsunami mean that this scale is rarely used. Abe introduced the ""tsunami magnitude scale formula_3"", calculated from, where ""h"" is the maximum tsunami-wave amplitude (in m) measured by a tide gauge at a distance ""R"" from the epicentre, ""a"", ""b"""
"from it empirically as a quantity without units, just a number designed to conform to the formula_3 scale. A spectral analysis is required to obtain formula_12, whereas the other magnitudes are derived from a simple measurement of the amplitude of a specifically defined wave. All scales, except formula_5, saturate for large earthquakes, meaning they are based on the amplitudes of waves which have a wavelength shorter than the rupture length of the earthquakes. These short waves (high frequency waves) are too short a yardstick to measure the extent of the event. The resulting effective upper limit of measurement for formula_17"
"decibels. In a similar vein, the peak signal-to-noise ratio is commonly used to assess the quality of sound and image compression methods using the logarithm. The strength of an earthquake is measured by taking the common logarithm of the energy emitted at the quake. This is used in the moment magnitude scale or the Richter magnitude scale. For example, a 5.0 earthquake releases 32 times and a 6.0 releases 1000 times the energy of a 4.0. Another logarithmic scale is apparent magnitude. It measures the brightness of stars logarithmically. Yet another example is pH in chemistry; pH is the negative"
"earthquakes can differ by as much as 1.4 units. Despite the usefulness of the scale, it is not generally used due to difficulties in estimating the radiated seismic energy. K (from the Russian word класс, ""class"", in the sense of a category) is a measure of earthquake magnitude in the ""energy class"" or ""K-class"" system, developed in 1955 by Soviet seismologists in the remote Garm (Tadjikistan) region of Central Asia; in revised form it is still used for local and regional quakes in many states formerly aligned with the Soviet Union (including Cuba). Based on seismic energy (K = log"
"deal with significant earthquakes larger than . For these events, the official magnitude is the moment magnitude , not Richter's local magnitude . The symbol for the moment magnitude scale is , with the subscript ""w"" meaning mechanical work accomplished. The moment magnitude is a dimensionless value defined by Hiroo Kanamori as where is the seismic moment in dyne⋅cm (10 N⋅m). The constant values in the equation are chosen to achieve consistency with the magnitude values produced by earlier scales, such as the Local Magnitude and the Surface Wave magnitude. Seismic moment is not a direct measure of energy changes"
"are the most destructive. Deeper earthquakes, having less interaction with the surface, produce weaker surface waves. The surface-wave magnitude scale, variously denoted as Ms, M, and M, is based on a procedure developed by Beno Gutenberg in 1942 for measuring shallow earthquakes stronger or more distant than Richter's original scale could handle. Notably, it measured the amplitude of surface waves (which generally produce the largest amplitudes) for a period of ""about 20 seconds"". The scale approximately agrees with at ~6, then diverges by as much as half a magnitude. A revision by , sometimes labeled M, measures only waves of"
"PHIVOLCS Earthquake Intensity Scale The PHIVOLCS Earthquake Intensity Scale (PEIS) is a seismic scale used and developed by the Philippine Institute of Volcanology and Seismology (PHILVOLCS) to measure the intensity of an earthquake. It was developed as a response to the 1990 Luzon earthquake. PHILVOLCS cites seismic scale specifically developed for the Philippine setting, the different geography of each country and other ""geological considerations"" led to the development of PEIS. The scale measures the effect of an earthquake on a given area based on its relative effect to people, structures and objects in the surroundings. The PEIS was adopted in"
"scale"", used in the Mediterranean Sea and the ""Imamura-Iida intensity scale"", used in the Pacific Ocean. The latter scale was modified by Soloviev, who calculated the Tsunami intensity ""I"" according to the formula where formula_2 is the average wave height along the nearest coast. This scale, known as the ""Soloviev-Imamura tsunami intensity scale"", is used in the global tsunami catalogues compiled by the NGDC/NOAA and the Novosibirsk Tsunami Laboratory as the main parameter for the size of the tsunami. In 2013, following the intensively studied tsunamis in 2004 and 2011, a new 12 point scale was proposed, the Integrated Tsunami"
"retain the logarithmic character of the original, and are scaled to have roughly comparable numeric values. Prior to the development of the magnitude scale the only measure of an earthquake's strength or ""size"" was a subjective assessment of the intensity of shaking observed near the epicenter of the earthquake, categorized by various seismic intensity scales such as the Rossi-Forel scale. In 1883 John Milne surmised that the shaking of large earthquakes might generate waves detectable around the globe, and in 1899 E. Von Rehbur Paschvitz observed in Germany seismic waves attributable to an earthquake in Tokyo. In the 1920s Harry"
"of Moment magnitude scale to replace the Richter magnitude scale for measuring the relative strength of earthquakes. The reason was that the Richter scale saturates at magnitudes greater than about 5.5, while the Moment magnitude scale does not saturate. Thomas C. Hanks Thomas C. Hanks is an American seismologist. He works for the US Geological Survey (USGS) in Menlo Park, California. Dr. Hanks is a member of the Seismological Society of America, the American Geophysical Union, the Earthquake Engineering Research Institute, the Geological Society of America, the Peninsula Geological Society at Stanford, and many related geological societies. Dr. Hanks has"
"either Ml, or M. (Not to be confused with the Russian surface-wave MLH scale.) Whether the values are comparable depends on whether the local conditions have been adequately determined and the formula suitably adjusted. In Japan, for shallow (depth < 60 km) earthquakes within 600 km, the Japanese Meteorological Agency calculates a magnitude labeled MJMA, M, or M. (These should not be confused with moment magnitudes JMA calculates, which are labeled M(JMA) or M, nor with the Shindo intensity scale.) JMA magnitudes are based (as typical with local scales) on the maximum amplitude of the ground motion; they agree ""rather"