The moment magnitude scale was introduced in 1979 by Thomas C. Hanks and Hiroo Kanamori as a successor to the Richter scale and is used by seismologists to compare the energy released by earthquakes.^{[1]} The moment magnitude M_{w} is a dimensionless number defined by Hiroo Kanamori (é‡‘æ£® åšé›„ Kanamori Hiroo; October 17, 1936â€”) is a seismologist who has made fundamental contributions to understanding the physics of earthquakes and the tectonic processes that cause them. ...
The Richter magnitude scale, or more correctly local magnitude ML scale, assigns a single number to quantify the amount of seismic energy released by an earthquake. ...
Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...
This article is about the natural seismic phenomenon. ...
In dimensional analysis, a dimensionless number (or more precisely, a number with the dimensions of 1) is a pure number without any physical units. ...
where M_{0} is the seismic moment (using one newton metre [N·m] as the reference moment).^{[citation needed]} Seismic moment is a quantity used by earthquake seismologists to measure the size of an earthquake. ...
Newton metre is the unit of moment (torque) in the SI system. ...
An increase of 1 step on this logarithmic scale corresponds to a 10^{1.5} = 31.6 times increase in the amount of energy released, and an increase of 2 steps corresponds to a 10³ = 1000 times increase in energy. A logarithmic scale is a scale of measurement that uses the logarithm of a physical quantity instead of the quantity itself. ...
The constants in the equation are chosen so that estimates of moment magnitude roughly agree with estimates using other scales, such as the Local Magnitude scale, M_{L}, commonly called the Richter magnitude scale. One advantage of the moment magnitude scale is that, unlike other magnitude scales, it does not saturate at the upper end. That is, there is no particular value beyond which all large earthquakes have about the same magnitude. For this reason, moment magnitude is now the most often used estimate of large earthquake magnitudes.^{[2]} The symbol for the moment magnitude scale is M_{w}, with the subscript w meaning mechanical work accomplished. The USGS does not use this scale for earthquakes with a magnitude of less than 3.5. The Richter magnitude scale, or more correctly local magnitude ML scale, assigns a single number to quantify the amount of seismic energy released by an earthquake. ...
In physics, mechanical work is the amount of energy transferred by a force. ...
The United States Geological Survey (USGS) is a scientific agency of the United States government. ...
This article is about the natural seismic phenomenon. ...
Radiated seismic energy
Potential energy is stored in the crust in the form of builtup stress. During an earthquake, this stored energy is transformed and results in Stress is a measure of force per unit area within a body. ...
 cracks and deformation in rocks,
 heat,
 radiated seismic energy E_{s}.
The seismic moment M_{0} is a measure of the total amount of energy that is transformed during an earthquake. Only a small fraction of the seismic moment M_{0} is converted into radiated seismic energy E_{s}, which is what seismographs register. Using the estimate Seismographs (in Greek seismos = earthquake and graphein = write) are used by seismologists to record seismic waves. ...
Choy and Boatwright defined in 1995 the energy magnitude Nuclear explosions The energy released by nuclear weapons is traditionally expressed in terms of the energy stored in a kiloton or megaton of the conventional explosive trinitrotoluene (TNT). The often quoted rule of thumb that a 1 kt TNT explosion is roughly equivalent to a magnitude 4 earthquake leads to the equation The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter A nuclear weapon derives its destructive force from nuclear reactions of fusion or fission. ...
A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ...
A megaton or megatonne is a unit of mass equal to 1,000,000 metric tons, i. ...
Rphrases Sphrases Related Compounds Related compounds picric acid hexanitrobenzene Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Trinitrotoluene (TNT) is a chemical compound with the formula C6H2(NO2)3CH3. ...
A rule of thumb is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination. ...
 .
where m_{TNT} is the mass of the explosive TNT that is quoted for comparison. Such comparison figures are not very meaningful. As with earthquakes, during an underground explosion of a nuclear weapon, only a small fraction of the total amount of energy transformed ends up being radiated as seismic waves. Therefore a seismic efficiency has to be chosen for a bomb that is quoted as a comparison. Using the conventional specific energy of TNT (4.184 MJ/kg), the above formula implies the assumption that about 0.5% of the bomb's energy is converted into radiated seismic energy E_{s}. For real underground nuclear tests, the actual seismic efficiency achieved varies significantly and depends on the site and design parameters of the test. This article or section does not adequately cite its references or sources. ...
The fuel value or relative energy density is the quantity of potential energy in fuel, food or other substance. ...
See also â€¹ The template below has been proposed for deletion. ...
The following is a list of major earthquakes. ...
A seismic scale is used to measure and compare the relative severity of earthquakes. ...
External links  USGS: What is moment magnitude?
References  ^ Hanks, Thomas C.; Kanamori, Hiroo (05/1979). "Moment magnitude scale". Journal of Geophysical Research 84 (B5): 23482350. Retrieved on 20071006.
 ^ Boyle, Alan (May 12, 2008). Quakes by the numbers. MSNBC. Retrieved on 20080512. “That original scale has been tweaked through the decades, and nowadays calling it the "Richter scale" is an anachronism. The most common measure is known simply as the moment magnitude scale.”
Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...
is the 279th day of the year (280th in leap years) in the Gregorian calendar. ...
For the news website, see msnbc. ...
2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ...
is the 132nd day of the year (133rd in leap years) in the Gregorian calendar. ...
Sources  Hanks TC, Kanamori H (1979). "A moment magnitude scale". Journal of Geophysical Research 84 (B5): 234850.
 Choy GL, Boatwright JL (1995). "Global patterns of radiated seismic energy and apparent stress". Journal of Geophysical Research 100 (B9): 1820528.
 Utsu,T., 2002, Relationships between magnitude scales, in: Lee, W.H.K, Kanamori, H., Jennings, P.C., and Kisslinger, C., editors, International Handbook of Earthquake and Engineering Seismology: Academic Press, a division of Elsevier, two volumes, International Geophysics, vol. 81A, pages 733746.. "{{{title}}}".
Journal of Geophysical Research is a publication of the American Geophysical Union. ...
Journal of Geophysical Research is a publication of the American Geophysical Union. ...
The European Macroseismic Scale (EMS) is the basis for evaluation of seismic intensity in European countries. ...
The MedvedevSponheuerKarnik scale (MSK64) is a macroseismic intensity scale used to measure the effects of earthquakes on humans, objects of nature, and structures. ...
The Mercalli intensity scale is a scale used for measuring the intensity of an earthquake. ...
The Japan Meteorological Agency seismic intensity scale (éœ‡åº¦ shindo) is a measure used in Japan to indicate the strength of earthquakes. ...
The Richter magnitude scale, or more correctly local magnitude ML scale, assigns a single number to quantify the amount of seismic energy released by an earthquake. ...
The Mercalli intensity scale is a scale used for measuring the intensity of an earthquake. ...
The Mercalli intensity scale is a scale used for measuring the intensity of an earthquake. ...
The RossiForel scale was one of the first seismic scales to reflect earthquake intensities. ...
