# Richter scale

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Related to Richter scale: Moment magnitude scale, tsunami

## Richter scale

(rĭk`tər), measure of the magnitude of seismic waves from an earthquakeearthquake,
trembling or shaking movement of the earth's surface. Most earthquakes are minor tremors. Larger earthquakes usually begin with slight tremors but rapidly take the form of one or more violent shocks, and end in vibrations of gradually diminishing force called
. Devised in 1935 by the American seismologist Charles F. Richter (1900–1985) and technically known as the local magnitude scale, it has been superseded by the moment magnitude scale, which was developed in the 1970s. The Richter scale is logarithmic; that is, the amplitude of the waves increases by powers of 10 in relation to the Richter magnitude numbers. The energy released in an earthquake can easily be approximated by an equation that includes this magnitude and the distance from the seismograph to the earthquake's epicenter. Numbers for the Richter scale range from 0 to 9, though no real upper limit exists. An earthquake whose magnitude is greater than 4.5 on this scale can cause damage to buildings and other structures; severe earthquakes have magnitudes greater than 7. Like ripples formed when a pebble is dropped into water, earthquake waves travel outward in all directions, gradually losing energy, with the intensity of earth movement and ground damage generally decreasing at greater distances from the earthquake focus. In addition, the nature of the underlying rock or soil affects ground movements. In order to give a rating to the effects of an earthquake in a particular place, the modified Mercalli scale, based on a scale developed by the Italian seismologist Giuseppe Mercalli, is often used. It measures an earthquake's intensity, the severity of an earthquake in terms of its effects on the inhabitants of an area, e.g., how much damage it causes to buildings.

## Richter scale

[′rik·tər ‚skāl]
(geophysics)
A scale of numerical values of earthquake magnitude ranging from 1 to 9.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

## Richter scale

a scale for expressing the magnitude of an earthquake in terms of the logarithm of the amplitude of the ground wave; values range from 0 to over 9
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Dec 23, 1972 - NICARAGUA - Massive earthquake measuring 6.5 on the Richter scale struck Managua.
It took place in the early hours of the morning on June 7, 1931 and measured 6.1 on the Richter scale.
The strongest earthquake which shook parts of Bulgaria was registered 27 kilometers off the Greek island Samothrace at 11:25 local time and was of magnitude 6.4 on the Richter scale.
An earthquake measuring 6.2 on the Richter scale jolted Ahar in East Azerbaijan province at 16:00 hours local time (1130GMT) on August 11.
According to European-Mediterranean Seismological Centre (EMSC), the earthquake measuring 4.8 on the Richter scale, struck Kathmandu at 6:14 am today.
It had magnitude 2.4 on Richter scale and a depth of 10.9 km.
ISLAMABAD, July 27, 2009 (Frontier Star) -- A strong earthquake measuring 5.2 on Richter scale jolted twin cities of Rawalpindi and Islamabad, Malakand division and Azad Jammu Kashmir, causing picnic among earthquake victim of October 08, 2005.
Summary: Islamabad [Pakistan], March 22 (ANI): An earthquake measuring 4.9 on the Richter scale rattled the parts of Malakand in Khyber Pakhtunkhwa province here on Friday.
A light earthquake with a magnitude of 2.3 on the Richter scale was registered in the southern Bulgarian city of Kardzhali early Sunday morning.
Summary: Jakarta, May 22, 2010, SPA -- An earthquake measuring 5 on the Richter scale jolted the eastern Indonesian province of Maluku on Friday night.
ISLAMABAD, July 05, 2009 (Frontier Star) -- A moderate earthquake measuring 5.1 on the Richter scale rattled various parts of the country including Islamabad, Sargodha, Swat and adjoining areas.
Nov 29 (ANI): An earthquake of magnitude 3.7 on the Richter scale hit Jammu and Kashmir region on Thursday.

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