Richter scale

The Richter scale is a scale of numbers used to tell the power (or magnitude) of earthquakes. Charles Richter developed the Richter Scale in 1935. His scale worked like a seismogram, measured by a particular type of seismometer at a distance of 100 kilometers (62 mi) from the earthquake. 

Earthquakes 4.5 or higher on the Richter scale can be measured all over the world. An earthquake a size that scores 3.0 is ten times the amplitude of one that scores 2.0. The energy that is released increases by a factor of about 32.

Every increase of 1 on the Richter scale corresponds to an increase in amplitude by a factor of 10 so therefore, it is a logarithmic scale.

+Richter Scale Magnitude Descriptor Richter Magnitude number Damage caused by the earthquake Frequency of occurrence Micro  Less than 2.0 Micro (very small) earthquakes, people cannot feel these. About 8,000 each day Very minor  2.0-2.9 People do not feel these, but seismographs are able to detect them. About 1,000 per day Minor  3.0-3.9 People often feel these, but they almost never cause damage. About 49,000 each year (About 134 per day) Light  4.0-4.9 Objects inside houses are disturbed, causing noise. Things are rarely damaged. About 6,200 each year (About 17 per day) Moderate  5.0-5.9 Buildings that are not built well may be damaged. Light objects inside a house may be moved. About 800 per year (About 2 per day) Strong  6.0-6.9 Moderately powerful.  May cause a lot of damage in a larger area. About 120 per year Major  7.0-7.9 Can damage things seriously over larger areas. About 18 per year Great  8.0-9.9 Massive damage is caused. Heavy objects are thrown into the air and cracks appear on the ground, as well as visible shockwaves. Overhead highways may be destroyed, and buildings are toppled. About 1 per 20 years Meteoric  10.0+ There are no records of anything of this size. The vibration is about the same as that of a 24 km (15 mi) meteor. Unknown
(Adapted from U.S. Geological Survey documents)

The earthquake with the biggest recorded magnitude was the Great Chilean Earthquake. It had a magnitude of 9.5 on the Richter scale and occurred in 1960. Around 6,000 people died because of the earthquake. No earthquake has ever hit 10+ on the Richter Scale.

More examples

 Approximate Richter Magnitude number Seismic energy equivalent: Amount of TNT Example event 0.5 5.6kg Large hand grenade 1.5 178kg Bomb used in WWII 2 1 metric ton Large Bomb used in WWII 2.5 5.6 metric tons Blockbuster bomb (dropped from airplanes) in WWII 3.5 178 metric tons Chernobyl accident, 1986 4 1 kiloton Small atomic bomb 5 32 kilotons Nagasaki atomic bombLincolnshire earthquake (UK), 20085.4150 kilotons[2008 Chino Hills earthquake] (Los Angeles, United States)5.5178 kilotonsLittle Skull Mtn. earthquake (NV, USA), 1992Alum Rock earthquake (CA, USA), 20076.01 megatonDouble Spring Flat earthquake (NV, USA), 19946.55.6 megatonsCaracas (Venezuela), 1967Rhodes (Greece), 2008Eureka Earthquake (Humboldt County CA, USA), 2010 6.716.2 megatonsNorthridge earthquake (CA, USA), 19946.926.8 megatonsSan Francisco Bay Area earthquake (CA, USA), 19897.032 megatonsJava earthquake (Indonesia), 2009, 2010 Haiti Earthquake7.1 50 megatonsEnergy released is equivalent to that of Tsar Bomba, the largest thermonuclear weapon ever tested1944 San Juan earthquake
2019 Ridgecrest, California earthquake7.5178 megatonsKashmir earthquake (Pakistan), 2005Antofagasta earthquake (Chile), 20077.8600 megatonsTangshan earthquake (China), 1976
North Canterbury (New Zealand) 20168.01 gigatonSan Francisco earthquake (CA, USA), 1906Queen Charlotte earthquake (BC, Canada), 1949México City earthquake (Mexico), 1985Gujrat earthquake (India), 2001Chincha Alta earthquake (Peru), 2007Sichuan earthquake (China), 2008 (initial estimate: 7.8)1894 San Juan earthquake8.55.6 gigatonsToba eruption 75,000 years ago; the largest known volcanic event.Petraglia, M.; R. Korisettar, N. Boivin, C. Clarkson,4 P. Ditchfield,5 S. Jones,6 J. Koshy,7 M.M. Lahr,8 C. Oppenheimer,9 D. Pyle,10 R. Roberts,11 J.-C. Schwenninger,12 L. Arnold,13 K. White. (6 July 2007). "Middle Paleolithic Assemblages from the Indian Subcontinent Before and After the Toba Super-eruption" . Science 317 (5834): 114–116. doi:10.1126/science.1141564. PMID 17615356.Sumatra earthquake (Indonesia), 20079.032 gigatons2011 Sendai, Japan Earthquake and Tsunami, Lisbon Earthquake (Lisbon, Portugal), All Saints Day, 17559.167 gigatonsIndian Ocean earthquake, 2004 (40 ZJ in this case)9.290.7 gigatonsAnchorage earthquake (AK, USA), 19649.5178 gigatonsValdivia earthquake (Chile), 196013.0108 megatons = 100 teratonsYucatán Peninsula impact (causing Chicxulub crater) 65 MYA ago.

Related pages
Mercalli intensity scale
Moment magnitude scale

References

 Other websites 
 Simplified description of the Richter scale

Category:Earthquakes
Category:Measurement