Richter magnitude scale

# Richter magnitude scale

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Encyclopedia
The expression Richter magnitude scale refers to a number of ways to assign a single number to quantify the energy contained in an earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

.

In all cases, the magnitude is a base-10 logarithmic scale
Logarithmic scale
A logarithmic scale is a scale of measurement using the logarithm of a physical quantity instead of the quantity itself.A simple example is a chart whose vertical axis increments are labeled 1, 10, 100, 1000, instead of 1, 2, 3, 4...

obtained by calculating the logarithm of the amplitude
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...

of waves measured by a seismograph
Seismometer
Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources...

. An earthquake that measures 5.0 on the Richter scale has a shaking amplitude 10 times larger and corresponds to an energy release of √1000 ≈ 31.6 times greater than one that measures 4.0.

## Development

Developed in 1935 by Charles Richter in partnership with Beno Gutenberg
Beno Gutenberg
Beno Gutenberg was a German-American seismologist who made several important contributions to the science...

, both of the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...

, the scale was firstly intended to be used only in a particular study area in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, and on seismograms recorded on a particular instrument, the Wood-Anderson torsion seismograph. Richter originally reported values to the nearest quarter of a unit, but values were later reported with one decimal place. His motivation for creating the local magnitude scale was to measure the ratio of small to larger earthquakes.

His inspiration was the apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

scale used in astronomy to describe the brightness of stars and other celestial objects. Richter arbitrarily chose a magnitude 0 event to be an earthquake that would show a maximum combined horizontal displacement of 1 µm (0.00004 in) on a seismogram recorded using a Wood-Anderson torsion seismograph 100 km (62.1 mi) from the earthquake epicenter. This choice was intended to prevent negative magnitudes from being assigned. The smallest earthquakes that could be recorded and located at the time were of magnitude 3, approximately. However, the Richter scale has no lower limit, and sensitive modern seismographs now routinely record quakes with negative magnitudes.

ML (local magnitude) was not designed to be applied to data with distances to the hypocenter
Hypocenter
The hypocenter refers to the site of an earthquake or a nuclear explosion...

of the earthquake greater than 600 km (373 mi). For national and local seismological observatories the standard magnitude scale is today still ML. Unfortunately this scale saturates at M6.5, approximately, because the high frequency waves recorded locally have wavelengths shorter than the rupture lengths of large earthquakes.

To be able to measure the size of earthquakes around the globe, Gutenberg and Richter later developed a magnitude scale based on surface waves, surface wave magnitude
Surface wave magnitude
The surface wave magnitude 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...

MS; and another based on body waves, body wave magnitude
Body wave magnitude
Body wave magnitude is a way of determining the size of an earthquake, using the amplitude of the initial P-wave to calculate the magnitude. The P-wave is a type of body wave that is capable of traveling through the earth at a velocity of around 5 to 8 km/s, and is the first wave from an...

mb. These are types of waves that are recorded at teleseismic distances. The two scales were adjusted such that they were consistent with the ML scale. This succeeded better with the Ms scale than with the mb scale. Both of these scales saturate when the earthquake is bigger than magnitude 8 and therefore the moment magnitude scale, Mw, was invented.

These older magnitude scales have been superseded by the implementation of methods for estimating the seismic moment
Seismic moment
Seismic moment is a quantity used by earthquake seismologists to measure the size of an earthquake. The scalar seismic moment M_0 is defined by the equationM_0=\mu AD, where*\mu is the shear modulus of the rocks involved in the earthquake...

, creating the moment magnitude scale
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

, although the former are still widely used because they can be calculated quickly.

## Details

The Richter scale proper was defined in 1935 for particular circumstances and instruments; the instrument used saturated for strong earthquakes. The scale was replaced by the moment magnitude scale
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

(MMS); for earthquakes adequately measured by the Richter scale, numerical values are approximately the same. Although values measured for earthquakes now are actually (MMS), they are frequently reported as Richter values, even for earthquakes of magnitude over 8, where the Richter scale becomes meaningless.
Anything above 5 is classed as a risk.

The Richter and MMS scales measure the energy released by an earthquake; another scale, the Mercalli intensity scale
Mercalli intensity scale
The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude M_w usually reported for an earthquake , which is a measure of the energy released...

, classifies earthquakes by their effects, from detectable by instruments but not noticeable to catastrophic. The energy and effects are not necessarily strongly correlated; a shallow earthquake in a populated area with soil of certain types can be far more intense than a much more energetic deep earthquake in an isolated area.

There are several scales which have historically been described as the "Richter scale," especially the local magnitude and the surface wave scale. In addition, the body wave magnitude, , and the moment magnitude, , abbreviated MMS, have been widely used for decades, and a couple of new techniques to measure magnitude are in the development stage.

All magnitude scales have been designed to give numerically similar results. This goal has been achieved well for , , and . The scale gives somewhat different values than the other scales. The reason for so many different ways to measure the same thing is that at different distances, for different hypocentral
Hypocenter
The hypocenter refers to the site of an earthquake or a nuclear explosion...

depths, and for different earthquake sizes, the amplitudes of different types of elastic waves must be measured.

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 is most common, although is also reported frequently.

The seismic moment
Seismic moment
Seismic moment is a quantity used by earthquake seismologists to measure the size of an earthquake. The scalar seismic moment M_0 is defined by the equationM_0=\mu AD, where*\mu is the shear modulus of the rocks involved in the earthquake...

, , 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. is derived from it empirically as a quantity without units, just a number designed to conform to the scale. A spectral analysis is required to obtain , whereas the other magnitudes are derived from a simple measurement of the amplitude of a specifically defined wave.

All scales, except , 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 is about 6.5 and about 8 for .

New techniques to avoid the saturation problem and to measure magnitudes rapidly for very large earthquakes are being developed. One of these is based on the long period P-wave, the other is based on a recently discovered channel wave.

The energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

release of an earthquake, which closely correlates to its destructive power, scales with the power of the shaking amplitude. Thus, a difference in magnitude of 1.0 is equivalent to a factor of 31.6 () in the energy released; a difference in magnitude of 2.0 is equivalent to a factor of 1000 ( ) in the energy released. The elastic energy radiated is best derived from an integration of the radiated spectrum, but one can base an estimate on because most energy is carried by the high frequency waves.

## Richter magnitudes

The Richter magnitude of an earthquake is determined from the logarithm
Logarithm
The logarithm of a number is the exponent by which another fixed value, the base, has to be raised to produce that number. For example, the logarithm of 1000 to base 10 is 3, because 1000 is 10 to the power 3: More generally, if x = by, then y is the logarithm of x to base b, and is written...

of the amplitude
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...

of waves recorded by seismographs (adjustments are included to compensate for the variation in the distance between the various seismographs and the epicenter of the earthquake). The original formula is:

where A is the maximum excursion of the Wood-Anderson seismograph, the empirical function A0 depends only on the epicentral distance of the station, . In practice, readings from all observing stations are averaged after adjustment with station-specific corrections to obtain the ML value.

Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude; in terms of energy, each whole number increase corresponds to an increase of about 31.6 times the amount of energy released, and each increase of 0.2 corresponds to a doubling of the energy released.

Events with magnitudes greater than about 4.6 are strong enough to be recorded by a seismograph anywhere in the world, so long as its sensors are not located in the earthquake's shadow.

The following describes the typical effects of earthquakes of various magnitudes near the epicenter. The values are typical only and should be taken with extreme caution, since intensity and thus ground effects depend not only on the magnitude, but also on the distance to the epicenter, the depth of the earthquake's focus beneath the epicenter, and geological conditions (certain terrains can amplify seismic signals).
Magnitude Description Earthquake effects Frequency of occurrence
Less than 2.0 Micro Micro earthquakes, not felt. Continual
2.0–2.9 Minor Generally not felt, but recorded. 1,300,000 per year (est.)
3.0–3.9 Often felt, but rarely causes damage. 130,000 per year (est.)
4.0–4.9 Light Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. 13,000 per year (est.)
5.0–5.9 Moderate Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well-designed buildings. 1,319 per year
6.0–6.9 Strong Can be destructive in areas up to about 160 kilometres (99.4 mi) across in populated areas. 134 per year
7.0–7.9 Major Can cause serious damage over larger areas. 15 per year
8.0–8.9 Great Can cause serious damage in areas several hundred kilometres across. 1 per year
9.0–9.9 Devastating in areas several thousand kilometres across.
1 per 10 years (est.)
10.0+ Massive Never recorded, widespread devastation across very large areas; see below for equivalent seismic energy yield.
Extremely rare (Unknown/May not be possible)

(Based on U.S. Geological Survey documents.)

Great earthquakes occur once a year, on average. The largest recorded earthquake was the Great Chilean Earthquake of May 22, 1960, which had a magnitude of 9.5 on the moment magnitude scale
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

.

### Examples

The following table lists the approximate energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

equivalents in terms of TNT
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...

explosive force – though note that the earthquake energy is released underground rather than overground. Most energy from an earthquake is not transmitted to and through the surface; instead, it dissipates into the crust and other subsurface structures. In contrast, a small atomic bomb blast (see nuclear weapon yield
Nuclear weapon yield
The explosive yield of a nuclear weapon is the amount of energy discharged when a nuclear weapon is detonated, expressed usually in the equivalent mass of trinitrotoluene , either in kilotons or megatons , but sometimes also in terajoules...

) will not simply cause light shaking of indoor items, since its energy is released above ground.

Following, 31.623 to the power of 0 equals 1, 31.623 to the power of 1 equals 31.623 and 31.623 to the power of 2 equals 1000. Therefore, an 8.0 on the Richter scale releases 31.623 times more energy than a 7.0 and a 9.0 on the Richter scale releases 1000 times more energy than a 7.0.
Approximate Magnitude Approximate TNT for
Seismic Energy Yield
Joule equivalent Example
0.0 15 g 63 kJ
0.2 30 g 130 kJ Large hand grenade
A hand grenade is any small bomb that can be thrown by hand. Hand grenades are classified into three categories, explosive grenades, chemical and gas grenades. Explosive grenades are the most commonly used in modern warfare, and are designed to detonate after impact or after a set amount of time...

0.5 85 g 360 kJ
1.0 480 g 2.0 MJ Small construction site blast
1.5 2.7 kg 11 MJ
2.0 15 kg 63 MJ
2.5 85 kg 360 MJ
3.0 480 kg 2.0 GJ
3.5 2.7 metric tons 11 GJ PEPCON fuel plant explosion
PEPCON disaster
The PEPCON disaster was an industrial disaster that occurred in Henderson, Nevada on May 4, 1988 at the Pacific Engineering Production Company of Nevada plant. The chemical fire and subsequent explosions claimed two lives, injured 372 people, and caused an estimated US\$100 million of damage...

, 1988
3.87 9.5 metric tons 40 GJ Explosion at Chernobyl nuclear power plant
Chernobyl disaster
The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine , which was under the direct jurisdiction of the central authorities in Moscow...

, 1986
3.91 11 metric tons 46 GJ Massive Ordnance Air Blast bomb
GBU-43/B Massive Ordnance Air Blast bomb
The GBU-43/B Massive Ordnance Air Blast bomb is a large-yield conventional bomb developed for the United States military by Albert L. Weimorts, Jr. At the time of development, it was touted as the most powerful non-nuclear weapon ever designed...

4.0 15 metric tons 63 GJ
4.3 43 metric tons 180 GJ Kent Earthquake (Britain), 2007
2007 Kent earthquake
The 2007 Kent earthquake was an earthquake that registered 4.3 on the Richter scale and struck south east Kent, England on 28 April 2007 at 07:18:12 UTC , at a shallow depth of 5.3 km....

4.5 85 metric tons 360 GJ Tajikistan earthquake, 2006
5.0 480 metric tons 2.0 TJ Lincolnshire earthquake (UK), 2008
2008 Lincolnshire earthquake
The 2008 Lincolnshire earthquake struck Lincolnshire, in the United Kingdom, on 27 February 2008 at 00:56:47.8s GMT. According to the British Geological Survey, the quake registered a reading of 5.2 on the Richter scale with the epicentre 2.5 miles north of Market Rasen and 15 miles ...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

The 2010 Central Canada earthquake was a magnitude 5.0 earthquake that occurred in Central Canada on June 23, 2010, at about 13:41:41 EDT and lasted about 30 seconds....

5.5 2.7 kilotons 11 TJ Little Skull Mtn. earthquake (Nevada, USA), 1992

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Alum Rock earthquake (California, USA), 2007
2007 Alum Rock earthquake
The 2007 Alum Rock earthquake occurred on October 30, 2007 at approximately 8:04 p.m. PDT in Alum Rock Park in San Jose, California...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Chino Hills earthquake (Los Angeles, USA), 2008
2008 Chino Hills earthquake
The 2008 Chino Hills earthquake occurred at 11:42:15 a.m. PDT on July 29, 2008, in Southern California. The epicenter of the magnitude 5.5 earthquake was in Chino Hills, approximately east-southeast of downtown Los Angeles....

5.6 3.8 kilotons 16 TJ Newcastle Earthquake Australia, 1989

Sparks Earthquake (Oklahoma, USA), 2011
6.0 15 kilotons 63 TJ Double Spring Flat earthquake (Nevada, USA), 1994
6.3 43 kilotons 180 TJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Rhodes earthquake (Greece), 2008
2008 Dodecanese earthquake
The 2008 Dodecanese earthquake, on 15 July 2008, was an earthquake near Kattavia on the island of Rhodes in the eastern Mediterranean Sea. The quake struck at 06:26 a.m. local time and one woman was killed when she slipped and fell as she tried to flee her home. However, the earthquake did...

Christchurch earthquake (New Zealand), 2011
6.4 60 kilotons 250 TJ Kaohsiung earthquake (Taiwan), 2010
2010 Kaohsiung earthquake
The 2010 Kaohsiung Earthquake measuring 6.4 ML occurred on Thursday, March 4, 2010 at 8:20 a.m. local time. The epicenter was located in the mountainous area of Kaohsiung County of the southwestern Taiwan. It was the most powerful earthquake in Kaohsiung since 1900...

6.5 85 kilotons 360 TJ
Surface wave magnitude
The surface wave magnitude 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...

Caracas earthquake (Venezuela), 1967
1967 Caracas earthquake
The 1967 Caracas earthquake occurred on 29 July 1967 at 20:00 local time, and was centered near the coast about 30 miles west of Caracas, capital of Venezuela with a magnitude of 6.5. When the earth stopped shaking, about 240 inhabitants were dead and hundreds injured and buried in the rubble where...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Eureka earthquake (California, USA), 2010
6.6 120 kilotons 500 TJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

San Fernando earthquake (California, USA), 1971
6.7 170 kilotons 710 TJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Northridge earthquake (California, USA), 1994
6.8 240 kilotons 1.0 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Nisqually earthquake (Anderson Island, WA), 2001

Gisborne earthquake (Gisborne, NZ), 2007
2007 Gisborne earthquake
The 2007 Gisborne earthquake was an earthquake of magnitude 6.8 on the Richter scale which struck in the Pacific Ocean, 50 km off the eastern coast of New Zealand's North Island at 8.55 pm NZDT on 20 December 2007...

6.9 340 kilotons 1.4 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

San Francisco Bay Area earthquake (California, USA), 1989

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Pichilemu earthquake (Chile), 2010
2010 Pichilemu earthquake
The 2010 Pichilemu earthquake , also known as the Libertador O'Higgins earthquake, was a 6.9 MW earthquake that struck Chile's O'Higgins Region on 11 March 2010 at 11:39 local time...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Sikkim earthquake (Nepal-India Border), 2011
2011 Sikkim earthquake
The 2011 Sikkim earthquake , also known as the 2011 Himalayan earthquake , was a magnitude 6.9 earthquake centered within the Kanchenjunga Conservation Area, near the border of Nepal and the Indian state of Sikkim, at 18:10 IST on Sunday, 18 September 2011...

7.0 480 kilotons 2.0 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Java earthquake (Indonesia), 2009

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Haiti earthquake, 2010
2010 Haiti earthquake
The 2010 Haiti earthquake was a catastrophic magnitude 7.0 Mw earthquake, with an epicentre near the town of Léogâne, approximately west of Port-au-Prince, Haiti's capital. The earthquake occurred at 16:53 local time on Tuesday, 12 January 2010.By 24 January, at least 52 aftershocks...

7.1 680 kilotons 2.8 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Messina earthquake (Italy), 1908
1908 Messina earthquake
The 1908 Messina earthquake and tsunami took some 100,000–200,000 lives on December 28, 1908 in Sicily and Calabria, southern Italy.-Quake:On December 28, 1908 from about 05:20 to 05:21 an earthquake of 7.2 on the moment magnitude scale occurred centered on the of city Messina, in Sicily. Reggio...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

San Juan earthquake (Argentina), 1944
1944 San Juan earthquake
The 1944 San Juan earthquake took place in the province of San Juan, in the center-west area of Argentina, a region highly prone to seismic events. This moderate to strong earthquake destroyed a large part of San Juan, the provincial capital, and killed 10,000 of its inhabitants, 10% of its...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Canterbury earthquake (New Zealand), 2010
2010 Canterbury earthquake
The 2010 Canterbury earthquake was a 7.1 magnitude earthquake, which struck the South Island of New Zealand at 4:35 am on local time ....

7.2 950 kilotons 4.0 PJ Vrancea earthquake (Romania), 1977

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Baja California earthquake (Mexico), 2010
2010 Baja California earthquake
The 2010 Baja California earthquake was an earthquake of 7.2 magnitude on the moment magnitude scale. It started south of Guadalupe Victoria, Baja California, Mexico, at a depth of . It occurred at 3:40:41 p.m...

7.5 2.7 megatons 11 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Kashmir earthquake (Pakistan), 2005
2005 Kashmir earthquake
The 2005 Kashmir earthquake was a major earthquake centered in Pakistan-administered Kashmir known as Azad Kashmir, near the city of Muzaffarabad, affecting Gilgit-Baltistan and Khyber Pakhtunkhwa province of Pakistan. It occurred at 08:52:37 Pakistan Standard Time on 8 October 2005...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Antofagasta earthquake (Chile), 2007
2007 Antofagasta earthquake
The 2007 Tocopilla earthquake was an earthquake registered on November 14, 2007 at 15:40:53 UTC . Its epicenter was located between the localities of Quillagua and Tocopilla, affecting the Tarapacá and the Antofagasta regions in northern Chile. The earthquake had a moment magnitude of 7.7 and...

7.6 3.8 megatons 16 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Gujarat earthquake (India), 2001
2001 Gujarat earthquake
The 2001 Gujarat earthquake occurred on January 26, 2001, India's 52nd Republic Day, at 08:46 AM local time and lasted for over two minutes. The epicentre was about 9 km south-southwest of the village of Chobari in Bhachau Taluka of Kutch District of Gujarat, India...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

İzmit earthquake (Turkey), 1999
1999 Izmit earthquake
The 1999 İzmit earthquake was a 7.6 magnitude earthquake that struck northwestern Turkey on August 17, 1999, at about 3:02am local time. The event lasted for 37 seconds, killing around 17,000 people and leaving approximately half a million people homeless...

7.7 5.4 megatons 22 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Sumatra earthquake (Indonesia), 2010
October 2010 Sumatra earthquake and tsunami
The October 2010 Sumatra earthquake was a magnitude 7.7 Mw earthquake that occurred on 25 October 2010 off the western coast of Sumatra, Indonesia at 21:42 local time . The earthquake occurred on the same fault that produced the 2004 Indian Ocean earthquake...

7.8 7.6 megatons 32 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Tangshan earthquake (China), 1976
1976 Tangshan earthquake
The Tangshan Earthquake also known as the Great Tangshan Earthquake, was a natural disaster that occurred on July 28, 1976. It is believed to be the largest earthquake of the 20th century by death toll. The epicenter of the earthquake was near Tangshan in Hebei, People's Republic of China, an...

Surface wave magnitude
The surface wave magnitude 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...

Hawke's Bay earthquake (New Zealand), 1931
1931 Hawke's Bay earthquake
The 1931 Hawke's Bay earthquake, also known as the Napier earthquake, occurred in New Zealand at 10:47 am on Tuesday 3 February 1931, killing 256 and devastating the Hawke's Bay region. It remains New Zealand's deadliest natural disaster...

Surface wave magnitude
The surface wave magnitude 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...

Luzon earthquake (Philippines), 1990
1990 Luzon earthquake
The Luzon earthquake occurred on Monday, July 16, 1990, at 4:26 PM local time in the Philippines. The densely populated island of Luzon was struck by an earthquake with a 7.8 Ms...

8.0 15 megatons 63 PJ
Surface wave magnitude
The surface wave magnitude 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...

Mino-Owari earthquake (Japan), 1891
1891 Mino-Owari earthquake
The was a large earthquake that struck the former provinces of Mino and Owari in the Nōbi Plain area during the Meiji period in Japan. It is also referred to as the Nōbi Earthquake or the Great Nōbi Earthquake . It is the largest known inland earthquake in Japan.-History:The earthquake struck on...

San Juan earthquake (Argentina), 1894
1894 San Juan earthquake
The 1894 San Juan earthquake was a major seismic movement that took place in the province of San Juan, Argentina, on 27 October 1894, at about 07:30 PM. It was the most powerful earthquake recorded in Argentina, with magnitude 8.0 on the Richter scale...

San Francisco earthquake (California, USA), 1906
1906 San Francisco earthquake
The San Francisco earthquake of 1906 was a major earthquake that struck San Francisco, California, and the coast of Northern California at 5:12 a.m. on Wednesday, April 18, 1906. The most widely accepted estimate for the magnitude of the earthquake is a moment magnitude of 7.9; however, other...

Surface wave magnitude
The surface wave magnitude 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...

Queen Charlotte Islands earthquake (B.C., Canada), 1949

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Chincha Alta earthquake (Peru), 2007
2007 Peru earthquake
The 2007 Peru earthquake was an earthquake measuring 8.0 on the moment magnitude scale that hit the central coast of Peru on Wednesday, August 15, 2007; it occurred at 23:40:57 UTC and lasted for about three minutes...

Surface wave magnitude
The surface wave magnitude 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...

Sichuan earthquake (China), 2008
2008 Sichuan earthquake
The 2008 Sichuan earthquake or the Great Sichuan Earthquake was a deadly earthquake that measured at 8.0 Msand 7.9 Mw occurred at 14:28:01 CST...

Kangra earthquake, 1905
1905 Kangra earthquake
1905 Kangra earthquake was a major earthquake that occurred in the Kangra Valley and the Kangra region of Himachal Pradesh in India on 4 April 1905. The earthquake measured 7.8 on the surface wave magnitude scale and killed more than 20,000 people...

8.1 21 megatons 89 PJ México City earthquake (Mexico), 1985
1985 Mexico City earthquake
The 1985 Mexico City earthquake, a magnitude 8.0 earthquake that struck Mexico City on the early morning of 19 September 1985 at around 7:19 AM , caused the deaths of at least 10,000 people and serious damage to the greater Mexico City Area. The complete seismic event...

Guam earthquake, August 8, 1993
8.35 50 megatons 210 PJ Tsar Bomba
Tsar Bomba
Tsar Bomba is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated. It was also referred to as Kuz'kina Mat , in this usage meaning "something that has not been seen before"....

- Largest thermonuclear weapon ever tested
8.5 85 megatons 360 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Sumatra earthquake (Indonesia), 2007
September 2007 Sumatra earthquakes
The September 2007 Sumatra earthquakes were a series of megathrust earthquakes that struck the Java Trench off the coast of Sumatra, Indonesia, three greater than magnitude 7. A series of tsunami bulletins was issued for the area...

8.7 170 megatons 710 PJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Sumatra earthquake (Indonesia), 2005
2005 Sumatra earthquake
The 2005 Sumatra earthquake, referred to as the Nias Earthquake by the scientific community, was a major earthquake on 28 March 2005, located off the west coast of northern Sumatra, Indonesia. Approximately 1300 people were killed by the earthquake, mostly on the island of Nias...

8.75 200 megatons 840 PJ Krakatoa
Krakatoa
Krakatoa is a volcanic island made of a'a lava in the Sunda Strait between the islands of Java and Sumatra in Indonesia. The name is used for the island group, the main island , and the volcano as a whole. The island exploded in 1883, killing approximately 40,000 people, although some estimates...

1883
8.8 240 megatons 1.0 EJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Chile earthquake, 2010
2010 Chile earthquake
The 2010 Chile earthquake occurred off the coast of central Chile on Saturday, 27 February 2010, at 03:34 local time , having a magnitude of 8.8 on the moment magnitude scale, with intense shaking lasting for about three minutes. It ranks as the sixth largest earthquake ever to be recorded by a...

,
9.0 480 megatons 2.0 EJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Lisbon earthquake (Portugal), All Saints Day, 1755
1755 Lisbon earthquake
The 1755 Lisbon earthquake, also known as the Great Lisbon Earthquake, was a megathrust earthquake that took place on Saturday 1 November 1755, at around 9:40 in the morning. The earthquake was followed by fires and a tsunami, which almost totally destroyed Lisbon in the Kingdom of Portugal, and...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

2011 Tōhoku earthquake and tsunami
2011 Tōhoku earthquake and tsunami
The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...

(Japan)
9.15 800 megatons 3.3 EJ Toba eruption 75,000 years ago; among the largest known volcanic events.
9.2 950 megatons 4.0 EJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Sumatra-Andaman earthquake and tsunami (Indonesia), 2004
2004 Indian Ocean earthquake
The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake...

9.5 2.7 gigatons 11 EJ
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

Valdivia earthquake (Chile), 1960
10.0 15 gigatons 63 EJ Never recorded
12.55 100 teratons 420 ZJ Yucatán Peninsula
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...

impact (creating Chicxulub crater
Chicxulub Crater
The Chicxulub crater is an ancient impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named...

) 65 Ma ago (108 megatons; over 4x1030 ergs = 400 ZJ).
32 1.5×1043 tons 6.3×1052 J Approximate magnitude of the starquake on the magnetar
Magnetar
A magnetar is a type of neutron star with an extremely powerful magnetic field, the decay of which powers the emission of copious high-energy electromagnetic radiation, particularly X-rays and gamma rays...

SGR 1806-20
SGR 1806-20
|- style="vertical-align: top;"| Distance | 50,000 light-years SGR 1806-20 is a magnetar, a particular type of neutron star. It has been identified as a soft gamma repeater. SGR 1806-20 is located about 14.5 kiloparsecs from Earth on the far side of our Milky Way galaxy in the constellation of...

, registered on December 27, 2004.
• Quakes using the more modern magnitude scales will denote their abbreviations:
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

and
Surface wave magnitude
The surface wave magnitude 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...

. Those that have no denoted prefix are
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

. Please be advised that the magnitude "number" (example 7.0) displayed for those quakes on this table may represent a significantly greater or lesser release in energy than by the correctly given magnitude (example
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

).

• Earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...

• Largest earthquakes by magnitude
• Seismic scale
Seismic scale
A seismic scale is used to calculate and compare the severity of earthquakes....

• Seismite
Seismite
Seismites are sedimentary beds disturbed by seismic shaking. The German paleontologist Adolf Seilacher first used the term in 1969 to describe a variety of post-depositional effects of seismic shocks on unconsolidated sediments...

• Mercalli intensity scale
Mercalli intensity scale
The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude M_w usually reported for an earthquake , which is a measure of the energy released...

• Moment magnitude scale
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...

• Japan Meteorological Agency seismic intensity scale
Japan Meteorological Agency seismic intensity scale
The Japan Meteorological Agency seismic intensity scale is a seismic scale used in Japan and Taiwan to measure the intensity of earthquakes. It is measured in units of...

• Order of magnitude
Order of magnitude
An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...

• Rohn Emergency Scale
Rohn Emergency Scale
The Rohn Emergency Scale is a scale on which the magnitude of an emergency is measured. It was first proposed in 2006, and explained in more detail in a peer-reviewed paper presented at a 2007 system sciences conference. The idea was further refined later that year. The need for such a scale was...

for measuring the magnitude (intensity) of any emergency