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The Moment Magnitude Scale (Mw) was developed by the seismologists Hanks and Kanamori during the 70's and their work was published in the Journal of Geophysical Research in 1979 (see the related link).
It was developed to enable seismologists to better estimate the magnitude of large earthquakes (those greater than 7) as the Local Magnitude (ML) or Richter scale originally developed in 1935 is not accurate at estimating earthquake magnitudes where the epicentre was greater than 600 km from the seismometer station or where the earthquake magnitude was greater than 7.0.
As such, the moment magnitude scale (MW) provides an estimate of the total energy released in an earthquake and is currently the preferred magnitude scale in use by seismologists in large earthquakes.
It is calculated from the seismic moment (M0 - which has the unit of dynes/cm =where 1 dyne/cm = 1x10-7 N/m) which is a measure of the total energy released during an earthquake and is derived based on the elastic moduli of the crust where the earthquake occurred, the length of the slip surface and the cross sectional area of the slip surface as follows:
M0 =G x AFx DF
Where:
G = Shear modulus of the rock mass
AF = Area of the rupture along the fault
DF = average displacement on AF
Seismic moment can also be estimated from the amplitude spectra of seismic waves as recorded by a seismometer.
In order to make the moment magnitude scale (Mw) consistent with older magnitude scales such as the Local Moment (or "Richter") scale the seismic moment (M0) is converted into a logarithmic scale using the following equation:
Mw = 2/3 x log10 x (M0) - 10.7
This ultimately yields a dimensionless number and as such, Moment Magnitude has no units.
Please see the related links.
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What system do geologists use today for rating the magnitude of an earthquake?
Geologists use the moment magnitude scale (Mw) to rate the magnitude of an earthquake today. This scale takes into account the seismic moment, which provides a more precise measurement of an earthquake's size compared to the Richter scale.
Who invented the moment magnitude scale?
The Moment Magnitude Scale (Mw) was developed by the seismologists Hanks and Kanamori during the 70's and their work was published in the Journal of Geophysical Research in 1979.
What scale is currently used to express the magnitude of earthquake?
The scale currently used to express the magnitude of earthquakes is the Richter scale or the moment magnitude scale (Mw). The moment magnitude scale is more commonly used today as it provides a more accurate measurement of an earthquake's size compared to the Richter scale.
What scale is used to measure the energy of an earthquake?
The energy of an earthquake is measured using the moment magnitude scale (Mw). This scale quantifies the total energy released during an earthquake by assessing the seismic moment, which is related to the fault rupture area and the average slip along the fault.
The amount of energy released by an eartquake is measured on the?
The amount of energy released by an earthquake is measured on the moment magnitude scale, often referred to as just magnitude. This scale takes into account the seismic moment, which is a measure of the total energy released during an earthquake. The magnitude is expressed in whole numbers and decimal fractions.
What scale describes an earthquake with a magnitude?
There are a number of earthquake magnitude scales, including the moment magnitude scale (the scale currently favoured by seismologists), the Richter or local magnitude scale and the surface wave magnitude scale.
What is the moment magnitude scale based on?
The Richter scale
What is the measure of an earthquakes strength called?
This is known as magnitude. It is measured on the moment magnitude scale.
What was the Japan Earthquake 2011 on the moment magnitude scale?
Magnitude of the 2011 Japan earthquake on moment magnitude scale is 9.0.The use of the Richter magnitude scale has largely been replaced by the moment magnitude scale in most countries. The United States Geological Survey (USGS), for example, uses the moment magnitude scale designated as MMS or Mw to measure all large earthquakes.UPDATE: Official magnitude was updated to 9.1 on Nov 7, 2016.
What are two advantages of the moment magnitude scale over the Richter scale?
The moment magnitude scale is more accurate for large earthquake than can cause damage.
What system do geologists use today for rating the magnitude of an earthquake?
Geologists use the moment magnitude scale (Mw) to rate the magnitude of an earthquake today. This scale takes into account the seismic moment, which provides a more precise measurement of an earthquake's size compared to the Richter scale.
What scale is used to measure to energy of an earthquake?
A magnitude scale. Formerly the Richter magnitude scale was used, but this has now been replaced by the Moment magnitude scale.
Who invented the moment magnitude scale?
The Moment Magnitude Scale (Mw) was developed by the seismologists Hanks and Kanamori during the 70's and their work was published in the Journal of Geophysical Research in 1979.
What does moment magnitude scale measures?
The moment magnitude scale (MW) provides an estimate of the total energy released in an earthquake and is currently the preferred magnitude scale in use by seismologists for measuring large (magnitude greater than 7) earthquakes.
What scale is currently used to express the magnitude of earthquake?
The scale currently used to express the magnitude of earthquakes is the Richter scale or the moment magnitude scale (Mw). The moment magnitude scale is more commonly used today as it provides a more accurate measurement of an earthquake's size compared to the Richter scale.
What are all of the scales for measuring earthquakes?
The main scales for measuring earthquakes are the Richter scale, the moment magnitude scale, and the Mercalli intensity scale. The Richter scale measures the amplitude of seismic waves, the moment magnitude scale considers the total energy released by an earthquake, and the Mercalli intensity scale measures the intensity of shaking and its effects on people and structures.
What scale is used to measure the energy of an earthquake?
The energy of an earthquake is measured using the moment magnitude scale (Mw). This scale quantifies the total energy released during an earthquake by assessing the seismic moment, which is related to the fault rupture area and the average slip along the fault.
