what scale is used to measure the damage of an earthquake
Wave Aamplitude, Fault Size, Amount of Slip
In that location are a number of ways to measure the magnitude of an earthquake. Most scales are based on the aamplitude of seismic waves recorded on seismometers. These scales business relationship for the distance betwixt the earthquake and the recording seismometer so that the calculated magnitude should be about the same no matter where information technology is measured. Some other calibration is based on the physical size of the convulsion mistake and the amount of slip that occurred. And then at that place are besides measures of earthquake shaking intensity. The intensity from one convulsion varies profoundly from place to place.
What's the difference between magnitude and intensity? This eight minute video uses the illustration of a lightbulb to explain the how an earthquake can have unlike intensities at different places.
Convulsion Intensity
What Controls the Shaking You Feel?
A few of these scales are described in more particular below.
The Richter Scale
The first widely-used method, the Richter scale, was adult past Charles F. Richter in 1934. It used a formula based on the amplitude of the largest wave recorded on a specific type of seismometer and the altitude between the earthquake and the seismometer. That calibration was specific to California earthquakes and chaff; other scales, based on wave amplitudes and total earthquake elapsing, were developed for use in other situations and they were designed to be consistent with Richter's calibration.
The Moment Magnitude Scale
Unfortunately, many scales, such every bit the Richter scale, practice not provide accurate estimates for big magnitude earthquakes. Today the moment magnitude scale, abbreviated MWestward , is preferred because it works over a wider range of earthquake sizes and is applicable globally. The moment magnitude scale is based on the total moment release of the earthquake. Moment is a production of the distance a fault moved and the strength required to move it. Information technology is derived from modeling recordings of the earthquake at multiple stations. Moment magnitude estimates are almost the same equally Richter magnitudes for small to large earthquakes. But merely the moment magnitude scale is capable of measuring M8 (read "magnitude 8") and greater events accurately.
Magnitudes are based on a logarithmic calibration (base 10). What this means is that for each whole number you go up on the magnitude scale, the amplitude of the ground motility recorded by a seismograph goes up x times. Using this scale, a magnitude 5 earthquake would result in x times the level of basis shaking as a magnitude four earthquake (and well-nigh 32 times as much energy would exist released). To requite you an idea how these numbers tin can add together up, remember of it in terms of the free energy released by explosives: a magnitude 1 seismic wave releases equally much energy as blowing upward 6 ounces of TNT. A magnitude 8 earthquake releases as much energy as detonating 6 million tons of TNT. Pretty impressive, huh? Fortunately, about of the earthquakes that occur each yr are much too pocket-sized to be felt by most people.
Magnitude scales can be used to draw earthquakes and so small that they are expressed in negative numbers. The scale also has no upper limit. The largest recorded convulsion occurred along the subduction zone in Chile in 1960. It was a magnitude ix.5 simply larger earthquakes may exist possible.
Fortunately, large earthquakes are much less common than modest ones. Here'south a table describing the magnitudes of earthquakes, their furnishings, and the estimated number of those earthquakes that occur each twelvemonth.
The Mercalli Scale
Another manner to measure out the strength of an earthquake is to utilize the observations of the people who experienced the earthquake, and the amount of damage that occurred, to estimate its intensity. The Mercalli scale was designed to do only that The original scale was invented by Giuseppe Mercalli in 1902 and was modified by Harry Woods and Frank Neumann in 1931 to go what is at present known as the Modified Mercalli Intensity Scale. To help distinguish information technology from magnitude scales, the MMI scale uses roman numerals.
Although the Mercalli scale does non apply scientific equipment to measure seismic waves, information technology has been very useful for understanding the damage caused past large earthquakes. It has likewise been used extensively to investigate earthquakes that occurred before there were seismometers.
Some factors that touch on the amount of damage that occurs are:
- the size (magnitude) of the earthquake
- the distance from the epicenter,
- the depth of the earthquake,
- the building (or other structure) pattern,
- and the type of surface material (rock or dirt) the buildings remainder on.
Unlike edifice designs hold up differently in an earthquake and the farther you are from the earthquake, the less impairment yous'll usually see. Whether a building is built on solid rock or sand makes a big difference in how much damage information technology sustains. Solid rock ordinarily shakes less than sand, then a building built on tiptop of solid stone shouldn't be as damaged every bit information technology might if it was sitting on a sandy lot.
Earthquake Magnitude Calibration
Source: https://www.mtu.edu/geo/community/seismology/learn/earthquake-measure/
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