Earthquake Magnitude and Intensity

HideShow resource information
  • Created by: Jelena
  • Created on: 15-05-13 15:37

Ways to Measure the Size of an Earthquake

  • 3 ways to measure the size of an earthquake
  • 1. Richter Magnitude
  • 2. Moment Magnitude
  • 3. Modified Mercalli Intensity Scale
1 of 4

Richter Magnitude

  • The amount of energy released during an earthquake is measured by its magnitude
  • Charles Richter took the logarithm of the largest ground motion registered by a seismograph as his emasure of earthquake magnitude and came up with the Richter Magnitude Scale
  • Two earthquakes at the same distance from a seismograph that dfifer in size of ground motion by a factor of 10 differ in magnitude by 1 Richter unit
  • Ex. the ground motion of an earthquake of magnitude 3 is 10 times that of an earthquake of magnitude 2
  • Ex. the ground motion of an earthquake of magnitude 6 is 100 times that of an earthquake of magnitude 4
2 of 4

Moment Magnitude

  • Most seismologists today use the Moment Magnitude Scale
  • A measurement more directly related to the physical properties of the faulting that causes the earthquake
  • Proportional to the logarithm of the area of the fault break and is approximately proportioned to the logarithm of the seismic energy released during the rupture
  • Both Richter's method and the Moment Magnitude method give roughly the same number
  • The Moment Magnitude can be measured more accurately from the seismographs, and it can also be deduced directly from field measurements of faulting
3 of 4

Modified Mercalli Scale

  • Measures the amount of damage done to the structures involved
  • This measurement, called the intensity of an earthquake, is determined using the modified Mercalli scales
  • This scale rates the types of damage and other effects of an earthquake as noted by observers during and after its occurrence
  • Scale uses Roman numerals I to XII to designate degree of intensity; the higher the numeral, the worse the damage
  • Specific effects or damage correspond to specific numerals
4 of 4


No comments have yet been made

Similar All resources:

See all All resources »