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Earthquake magnitudes are measured using seismometers. Based on the amplitude of the seismic waves, seismologists can make a preliminary estimate of the moment and Richter magnitudes of the earthquake.
For a more accurate estimate of the energy released, seismologists use the moment magnitude scale (MW).
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 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
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.
Earthquake intensity is measured using the Modified Mercalli Scale. The scale indicates the perceived damage from an earthquake. These parameters are subjective: they depend on the conditions of buildings and the opinions of witnesses. In order to make the measurements more objective, ground accelerations as measured by seismometers are also used to calculate earthquake intensity.
On the Richter scale.
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BeauEarthquakes are measured using a seismometer to detect ground motion. The magnitude of an earthquake is typically determined using the Richter scale or the moment magnitude scale, which quantifies the energy released by the earthquake. The intensity of an earthquake, on the other hand, is measured using the Modified Mercalli Intensity (MMI) scale, which assesses its impact on people and structures.
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What is the range of mantitude for earthquakes and what sacle is used to measure them?
The magnitude of earthquakes typically ranges from <0 (microearthquakes) to >9 (great earthquakes). The most commonly used scale to measure earthquake magnitude is the Richter Scale or the moment magnitude scale.
How is intensity or energy of earthquakes measured?
The intensity of earthquakes is measured using the Modified Mercalli Intensity (MMI) scale, which assesses the effects of an earthquake at a given location. The energy released during an earthquake is measured using the moment magnitude scale (Mw), which takes into account the seismic moment and rupture length of the earthquake.
What it measured on the Richter scale?
The Richter scale measures the magnitude of seismic waves produced by an earthquake, which provides an estimate of the energy released at the earthquake's source. A higher Richter scale number indicates a stronger earthquake.
Write a note on earthquakes?
Earthquakes are caused by the sudden release of energy in the Earth's crust, leading to the shaking and movement of the ground. They can cause destruction of buildings and infrastructure, as well as trigger landslides and tsunamis. Earthquakes are often measured using the Richter scale to quantify their magnitude.
Why can't you use a Mercalli scale to measure undersea earthquake?
The Mercalli scale is a measure of the intensity of shaking felt during an earthquake on land, based on observed effects. Since undersea earthquakes are below the ocean's surface, there are no direct observations to gauge the effects of shaking on land structures or people. Instead, scientists use the moment magnitude scale to measure the size of undersea earthquakes based on seismic data.
