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Earthquake
Energy Calculator |

The
occurrence of an earthquake is a complex energy
conversion process. When an
earthquake occurs,

much of the available local energy is used to power the earthquake fracture growth, producing heat rather than

generating seismic waves which radiate outward and are detected by seismographs.

The seismic moment is a measure of the total amount of energy that is transformed during an earthquake.

Usually only 1-10 percent or less of an earthquake's total energy is released in the form of radiated seismic waves.

How much energy is converted / released in an earthquake?

(1) Enter the published Earthquake Magnitude value into the table

(2) Click "Compute" or press Return/Enter on keyboard

(3) Compare energy levels in various equivalent measures

earthquake. Richter, working with Dr. Beno Gutenberg, developed a relationship between magnitude and energy.

That relationship is:

much of the available local energy is used to power the earthquake fracture growth, producing heat rather than

generating seismic waves which radiate outward and are detected by seismographs.

The seismic moment is a measure of the total amount of energy that is transformed during an earthquake.

Usually only 1-10 percent or less of an earthquake's total energy is released in the form of radiated seismic waves.

How much energy is converted / released in an earthquake?

(1) Enter the published Earthquake Magnitude value into the table

(2) Click "Compute" or press Return/Enter on keyboard

(3) Compare energy levels in various equivalent measures

Richter Scale vs Moment Magnitude Scale

Since
the late 1930s it became commonplace to measure earthquakes by
their magnitude, given the work done

by Gutenberg and Richter, and the publication of
the logarithmic Richter Scale which
related to a measure of the

energy radiated by the
earthquake, using well-calibrated seismic
stations. At the time, the general properties of

the radiated spectrum
were not known
and the concept of seismic moment and the moment tensor

had not yet
been developed.

The
Richter scale only describes the maximum wave amplitude, and does not give any indication of the total energy

that is released
by the event. The moment magnitude scale
measures
the total energy
released by an earthquake.

It now supersedes the Richter magnitude
scale which
measures the height of a seismic wave. The two scales will

indicate similar
results if the earthquake magnitudes are between 3.0
and 7.0.

Seismologists studying
larger
earthquakes (greater than M3.5 - M4.0) generally report the size of the
earthquake

using the moment
magnitude scale.
For
smaller earthquakes, the published magnitude
is usually given as M_{B},

M_{S,}
or M_{L.} The
concept of moment magnitude (M_{W}) was introduced
in 1979 by Hanks and
Kanamori and has

since become the most commonly used method of
describing the size of an event. Moment magnitude
measures

the size of events in terms of how much total energy is
released.

More Information about Earthquake Magnitude and Seismic Moment

Specifically,
moment magnitude relates to the
amount of movement by rock; i.e. the distance of movement

along a fault
or fracture and the area of the
fault or fracture surface.
It is calculated as

M_{O}
= µAD

where µ is the shear modulus of the
rocks included in the fault (dyne/cm^{2})

A is the area of the fault rupture in cm^{2}

and D is the average fault displacement in cm

Thus, M_{O} is shown in units of energy,
dyne-cm

earthquake. Richter, working with Dr. Beno Gutenberg, developed a relationship between magnitude and energy.

That relationship is:

logES =
11.8 + 1.5M

giving the energy ES in ergs from the magnitude M.

Note that
ES is not
the total "intrinsic'' energy of the earthquake, transferred
from
sources such as gravitational energy

or to sinks such as heat energy. It is
only the amount radiated from the earthquake as seismic waves, which, as was

said above, is in most cases only a small fraction of the
total energy
transferred during the
earthquake
process.