Earthquake Magnitude Scale Definition

Estimated number each year.

Earthquake magnitude scale definition. Earthquake earthquake intensity and magnitude of earthquakes. The moment magnitude scale was designed to produce a more accurate accounting of the total energy released by an earthquake and it calculates the earthquake s magnitude more accurately than other measures such as the richter scale m l the body wave scale m b and the surface wave scale m s the moment magnitude scale considers the fault s geometry the angle and other. The violence of seismic shaking varies considerably over a single affected area.

Often felt but. The magnitude is a number that characterizes the relative size of an earthquake. Magnitude is expressed in whole numbers and decimal fractions.

Because the entire range of observed effects is not capable of simple quantitative definition the strength of the shaking is commonly estimated by reference to intensity scales that describe the effects in qualitative terms. The types and nature of these waves are described in the section seismic waves because the size of earthquakes varies enormously it is necessary for purposes of comparison to compress the range of wave amplitudes. Richter and presented in his landmark 1935 paper where he called it the magnitude scale.

Magnitude is based on measurement of the maximum motion recorded by a seismograph several scales have been defined but the most commonly used are 1 local magnitude ml commonly referred to as richter magnitude 2 surface wave magnitude ms 3 body wave magnitude mb and 4 moment. Seismic magnitude scales are used to describe the overall strength or size of an earthquake these are distinguished from seismic intensity scales that categorize the intensity or severity of ground shaking quaking caused by an earthquake at a given location. The richter scale also called the richter magnitude scale or richter s magnitude scale is a measure of the strength of earthquakes developed by charles f.

This was later revised and renamed the local magnitude scale denoted as ml or m l. Because of the logarithmic basis of the scale each whole number increase in magnitude represents a tenfold increase in measured amplitude as measured on a seismogram. Magnitudes are usually determined from measurements of an earthquake s seismic waves as recorded on a seismogram.

Usually not felt but can be recorded by seismograph. Richter scale widely used quantitative measure of an earthquake s magnitude size devised in 1935 by american seismologists charles f. Earthquake magnitude is a measure of the size or amplitude of the seismic waves generated by an earthquake source and recorded by seismographs.

Richter and beno gutenberg. Because of various shortcomings of the m l scale most. For example a magnitude 5 3 is a moderate earthquake and a 6 3 is a strong earthquake.

Denoted explicitly with m w or mw and generally implied with use of a single m for magnitude is a measure of an earthquake s magnitude size or strength based on its seismic moment a measure of the work done by the earthquake it was defined in a 1979 paper by thomas c.