Measuring Earthquakes (5-2 Notes)

Magnitude = a measure of an earthquake’s strength Based on seismic waves

Seismograph = a device that records ground movements caused by seismic waves

Seismogram A paper or graph created by the seismograph

Rating Earthquakes 1) Mercalli Scale 2) Richter Scale 3) Moment Magnitude Scale

Mercalli Scale Rarely used. The same earthquake can have different Mercalli ratings.

Richter Scale Assigns a magnitude number based on the size of seismic waves.

Richter Scale Accurate for small, nearby earthquakes. Problem: Does not work well for large or distance quakes.

Moment Magnitude Scale Estimates total energy released.

Moment Magnitude Scale Extremely accurate for all sizes of earthquakes, both near or far.

Moment Magnitude Scale Most often used in news reports.