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Topic: Richter magnitude

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	Richter magnitude scale (Site not responding. Last check: 2007-10-12)
		Richter's local magnitude scale was originally to be used only in a particular area in California and on seismograms recorded a particular instrument the Wood-Anderson torsion seismometer.
		Richter magnitude is a logarithmic scale obtained by calculating the logarithm of combined horizontal amplitude of the largest displacement from zero a seismogram.
		Richter arbitrarily chose a magnitude 0 event be an earthquake that would show a combined horizontal displacement of 1 micrometre on seismogram recorded using a Wood-Anderson torsion seismometer 100 km from the earthquake epicenter.
	www.freeglossary.com /Richter_scale (673 words)

	ipedia.com: Richter magnitude scale Article (Site not responding. Last check: 2007-10-12)
		Richter's local magnitude scale was originally intended to be used only in a particular study area in California, and on seismograms recorded on a particular instrument, the Wood-Anderson torsion seismometer.
		Richter's motivation for creating the local magnitude scale was to separate the vastly larger number of smaller earthquakes from the relatively fewer larger earthquakes observed in California at the time.
		Richter arbitrarily chose a magnitude 0 event to be an earthquake that would show a maximum combined horizontal displacement of 1 micrometre on a seismogram recorded using a Wood-Anderson torsion seismometer located 100 km from the earthquake epicenter.
	www.ipedia.com /richter_magnitude_scale_1.html (699 words)

	SCSN - The Southern California Seismic Network
		Unlike other methods of earthquake magnitude, it is directly related to the size of rupture and the amount of slip on the rupture surface, and not based solely on empirical studies of the observed instrumental recordings.
		Local magnitude, as practiced today, is derived directly from Charles Richter's original magnitude scale: the magnitude is the logarithm (base 10) of the amplitude in microns on a Wood-Anderson torsion seismometer located 100 km from the earthquake (in other words, if the amplitude is 1.0 mm at this distance, the quake is a 3.0).
		Magnitude estimate is computed for each available horizontal component, and the mean or median of the values is taken as the earthquake magnitude.
	www.scsn.org /magnitude.html (1112 words)

	The Richter Magnitude Scale, Alaska Science Forum
		In the examples shown, a magnitude 2 earthquake would produce a deflection of 0.1 millimeter from an earthquake 100 kilometers away, or a deflection of 2 millimeters if it were only 20 kilometers distant.
		Magnitude scales in general often seem to be devised with a devilish intent to mislead.
		The magnitude of a disaster, for instance, goes up as the disaster becomes worse, but the magnitude of a star goes down as the intrinsic brightness becomes greater.
	www.gi.alaska.edu /ScienceForum/ASF7/701.html (800 words)

	ARIZONA SEISMICITY: EARTHQUAKE SIZE AND INTENSITY (Site not responding. Last check: 2007-10-12)
		Magnitude is determined by analyzing the amplitude of seismic waves recorded for an earthquake.
		The Richter scale is simply a scale of the energy released by an earthquake, and Richter magnitude is determined by the amplitude, or size, or the ground movement caused by seismic waves.
		Richter magnitude utilizes seismic waves from only a small part of the fault rupture and therefore does not fully account for the total energy released in a large earthquake.
	www.geo.arizona.edu /~dgreen/azseis3.htm (1023 words)

	Paper Artcle - The Island (Site not responding. Last check: 2007-10-12)
		The Richter magnitude scale was introduced by Charles F. Richter, a scientist in the California Institute of Technology in 1935.
		Richter’s scale was developed based on the Stellar magnitude scale used in astronomy to describe the brightness of stars and other celestial objects.
		The magnitude of an earthquake is determined from the logarithm of the amplitude of the strongest wave recorded by seismographs.
	www.gissl.lk /paper_articles_tsunami/article_11.htm (797 words)

	What is meant by an earthquake's magnitude? (Site not responding. Last check: 2007-10-12)
		The Richter Magnitude Scale, as it has come to be known, is a measure of the amplitude of the seismic waves produced at the source of an earthquake.
		An increase of one unit on the Richter Scale, for example from magnitude 6.0 to 7.0, corresponds to a 10-fold increase in the amplitude of the seismic waves that shake the ground.
		Magnitude is related to the energy radiated from the earthquake source as seismic waves.
	www.jclahr.com /alaska/aeic/magnitude/mag_basics.html (185 words)

	The San Andreas Fault - VIII. "Magnitude" and "Intensity" (Site not responding. Last check: 2007-10-12)
		Magnitude is a measure of the size of an earthquake.
		As the Richter scale does not adequately differentiate between the largest earthquakes, a new "moment magnitude" scale is being used by seismologists to provide a better measure.
		On the moment magnitude scale, the San Francisco earthquake is estimated at magnitude 7.7 compared to an estimated Richter magnitude of 8.3.
	pubs.usgs.gov /gip/earthq3/magnitude.html (332 words)

	Measurement - Richter Magnitude (Site not responding. Last check: 2007-10-12)
		Richter Magnitude is a number that indicates the strength of an earthquake.
		Scientists calculate Richter magnitude by using information obtained from seismograph, an instrument that records an earthquake's ground motion.
		The highest Richter magnitude ever recorded is 8.9, recorded in the Pacific Ocean near the Colombia-Ecuador border in 1906, and again in Japan in 1933.
	library.thinkquest.org /C005686/htmfiles/richtermagnitude.htm (201 words)

	Page 19 -- Measuring Earthquakes
		Though initial magnitude estimates are sometimes revised slightly as more data is gathered and analyzed, a lot of the claims that the magnitude of an earthquake was "altered" by some institution (e.g.
		Moment Magnitude: The moment magnitude scale is a way of rating the seismic moment of an earthquake with a simple, logarithmic numerical scale similar to the original Richter magnitude scale.
		Surface-wave Magnitude: Surface-wave magnitude is calculated using the amplitude, on a long-period vertical seismometer, of surface waves with a 20-second period.
	www.data.scec.org /Module/sec3pg19.html (545 words)

	Geography: the use of the Ricter Scale
		The Richter magnitude scale was developed in 1935 by Charles F. Richter of the California Institute of Technology as a mathematical device to compare the size of earthquakes.
		Adjustments are included in the magnitude formula to compensate for the variation in the distance between the various seismographs and the epicenter of the earthquakes.
		Richter's magnitude scale was first created for measuring the size of earthquakes occurring in southern California, using relatively high-frequency data from nearby seismograph stations.
	en.allexperts.com /q/Geography-1729/use-Ricter-Scale.htm (774 words)

	Richter Magnitude (Site not responding. Last check: 2007-10-12)
		The uncertainty in an estimate of the magnitude is about plus or minus 0.3 units, and seismologists often revise magnitude estimates as they obtain and analyze additional data.
		Richter showed that, the larger the intrinsic energy of the earthquake, the larger the amplitude of ground motion at a given distance.
		Both the magnitude and the seismic moment are related to the amount of energy that is radiated by an earthquake.
	www.seismo.unr.edu /ftp/pub/louie/class/100/magnitude.html (1477 words)

	lwf16
		Richter defined seismic magnitude in terms of a particular type of recording device, called a Wood-Anderson seismograph, situated at a standard distance of 100 kilometers from an earthquake's epicenter.
		Richter appropriated from astronomy the idea of a logarithmic scale —; based on powers of 10 — to accommodate the incredible range of earthquake sizes.
		It is true that the Richter magnitude scale is logarithmic, but this does not mean a magnitude 8 quake is 10 times stronger than a magnitude 7.
	geowords.com /e125/richter.htm (1195 words)

	SpiNet \| 1960 Chilean Earthqauke
		In designing his magnitude scale, Richter determined the relative size of an earthquake by comparing it to a reference earthquake recorded on a Wood-Anderson seismometer at a distance of 100 km from the epicenter.
		Although the local or Richter magnitude is useful, the limitations imposed by instrument type and the distance range make it impractical for determining size of earthquakes recorded world wide.
		This magnitude scale is called the Body Wave magnitude, mb, and is based on the first few cycles of the P wave (primary or first) arrival.
	www.scieds.com /spinet/historical/chile_mag.html (920 words)

	H e a r t l a n d S c i e n c e - - The Ohio Academy of Science -
		The Richter magnitude is calculated from the amplitude of the largest seismic wave recorded for the earthquake.
		Richter magnitudes are based on a logarithmic scale.
		Magnitude 8.0 or greater is a formidable earthquake.
	www.heartlandscience.org /medhs/richter.htm (326 words)

	richter scale
		The Richter scale, used to measure earthquake intensity, was developed in 1953 by Charles Richter.
		IT measures an earthquake's magnitude (intensity) on a scale of 1 to 8.8 which means that each whole number on the scale represents a 10-fold increase in power.
		Each magnitude number represents the maximum amplitude of a seismic wave at a distance of about 100 miles (161 kilometers).
	library.thinkquest.org /22360/richter.html (108 words)

	The Richter Scale (Site not responding. Last check: 2007-10-12)
		The Richter magnitude scale was orginally developed by Charles Richter and Beno Gutenberg to make more quantitative measures of the relative sizes of earthquakes in southern California.
		The Richter magnitude is related to the maximum amplitude of the S wave measured from the seismogram.
		Thus, a magnitude 7 (M 7) earthquake is 10 times as large as a magnitude 6 earthquake, and releases over 30 times more energy.
	www.thetech.org /exhibits_events/online/quakes/grams/richter.html (99 words)

	Earthquake Hazards Program: An Interview with Charles F. Richter (Site not responding. Last check: 2007-10-12)
		He is best known to the public for the Richter magnitude scale; but he is equally recognized in the scientific community for many other contributions to seismology including his books Elementary Seismology (1958) and Seismicity of the Earth (coauthored in 1954 with Beno Gutenberg).
		Yes, without any significant contribution from me, he later worked out a version of the magnitude scale that used the measured amplitudes and periods of body waves, that is P (primary), S (secondary), and PP (P waves that are reflected at the Earth's outer surface and then continue on as P waves).
		For instance, magnitude is sometimes assigned on the first few waves of the P group rather than the largest P waves as Gutenberg did.
	wwwneic.cr.usgs.gov /neis/seismology/people/int_richter.html (1855 words)

	Richter Scale, etc. (Site not responding. Last check: 2007-10-12)
		In 1935, Charles Richter was looking for a simple way to categorize earthquakes by the energy they release, rather than subjective descriptions of their impacts on human settlements.
		Because the energy at a given frequency is related to the size of the fault that produced the earthquake, the scale tends to 'saturate' when an earthquake reaches a certain size.
		That's why a new magnitude scale was developed in the 1980's; the moment-magnitude scale relies on the lowest seismic frequencies, which are most sensitive to the scale of the earthquake-producing fault.
	amos.indiana.edu /library/scripts/richter.html (251 words)

	Richter magnitude scale: earthquakes: office of emergency management: departments: City of Fort Collins
		His method, known as the "Richter Magnitude Scale" uses a scientific logarithm to determine the magnitude of an earthquake by measuring the acceleration of the ground during a shock.
		However, the magnitude of the strongest quake ever recorded (Chili, 1960) was around 9.0 on Richter's Scale.
		The interesting thing about the Richter Scale is that for each incremental rating of one that an earthquake scores, its strength or energy is actually multiplied by a factor of 10.
	www.fcgov.com /oem/richter-scale.php (282 words)

	ABAG On Shaky Ground - Magnitude (Site not responding. Last check: 2007-10-12)
		Magnitude is a measure of overall earthquake size.
		Thus, one principal factor in determining shaking hazard is the magnitude of the earthquake.
		The moment magnitude is proportional to the area of the fault surface that has slipped.
	www.abag.ca.gov /bayarea/eqmaps/doc/big.html (185 words)

	Measurement
		Magnitude does not depend on population and effects to ground structures, but rather on wave amplitude and distance.
		This magnitude scale is logarithmic, meaning each step in magnitude is exponentially greater than the last.
		These magnitude scales differ by the type of wave amplitude that is measured from the seismogram and the mathematical formula used to determine the magnitude.
	scign.jpl.nasa.gov /learn/eq8.htm (492 words)

	The Richter Scale - www.on-this-day.com (Site not responding. Last check: 2007-10-12)
		The Richter magnitude scale was developed in 1935 by Charles F. Richter of the California Institute of Technology.
		On the Richter Scale, the magnitude of quake is expressed in whole numbers and decimal fractions.
		Quakes with magnitudes of 4.5 or greater are recordable by seismographs all over the world.
	www.on-this-day.com /onthisday/docs/assorted/richterscale.htm (161 words)

	Earthquake Magnitude: THE RICHTER SCALE (ML) (Site not responding. Last check: 2007-10-12)
		The original magnitude scale of Richter (1935) was introduced for the purpose of providing an objective measure of the energy of each earthquake in the initial listing of earthquakes in the southern California region compiled by the Seismological Laboratory in Pasadena.
		Although Richter (1935) predicted that the local-magnitude scale "cannot hold to any high accuracy," history has proved it to be a powerful quantitative tool for ordering the relative sizes of earthquakes.
		Thus, the "correct" Richter magnitude ML=6.9 for the great 1906 earthquake obtained by Jennings and Kanamori (1979) reflects the amplitude of seismic waves at periods near 1 s but not the total energy of this earthquake.
	www.johnmartin.com /earthquakes/eqsafs/safs_693.htm (371 words)

	How Are Earthquake Magnitudes Measured?
		The Richter magnitude is calculated from the amplitude of the largest seismic wave recorded for the earthquake, no matter what type of wave was the strongest.
		Using this scale, a magnitude 5 earthquake would result in ten times the level of ground shaking as a magnitude 4 earthquake (and 32 times as much energy would be released).
		Here's a table describing the magnitudes of earthquakes, their effects, and the estimated number of those earthquakes that occur each year.
	www.geo.mtu.edu /UPSeis/intensity.html (471 words)

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