Geological Survey Program

Relationship of Increasing Magnitudes

Great Central U.S. ShakeOut! | Earthquake Science | SEMA Preparedness | FEMA Preparedness | FEMA Mitigation
Recent Earthquakes | Earthquake Awareness Month Activities | Preparedness Videos Created by Students

The Richter magnitude scale is commonly used but often misunderstood

Each whole-number step of magnitude represents a tenfold increase in amplitude. Therefore, the amplitude of an 8.3-magnitude earthquake is not twice that of a magnitude 4.3 quake but rather 10,000 times as large.

The volumes of the spheres shown here are scaled to illustrate the relative increase in magnitude. At this scale, magnitudes of 1, 2, 3 and 4 would be roughly proportional to a small marble, a golf ball, a grapefruit and a basketball.

At the same time, the energy released by an earthquake of magnitude 8.7 could be represented by the sphere the size of a hot-air balloon.

Earthquake Facts

• Facts About New Madrid Seismic Zone
• History of Earthquakes in Missouri
• Understanding Earthquakes
• Measuring Earthquakes
• Relationship of Increasing Magnitudes
• Relationship Between Richter Magnitude and Modified Mercalli Intensity
• Recent Earthquakes in Central US
• What to do before, during and after an earthquake
• Earthquake Hazard in the New Madrid Seismic Zone Remains a Concern
• Eyewitness Accounts of the 1811-12 New Madrid Earthquakes
• Did you feel it?
• Missouri Seismic Safety Commission
• Additional Links