The Richter Scale

• The Richter scale measures the magnitude of an earthquake based on ground shaking and energy released.
• It is not a measure of destruction caused.
• Seismologist Charles Richter invented it in 1935.
• Richter was inspired to study seismology at the California Institute of Technology.
• Richter was an assistant to seismologist Beno Gutenburg.
• Initially, it was for Southern California earthquakes, but is now used worldwide.

Importance and Uses

• The Richter scale is a standard for classifying earthquake magnitude.
• It is most effective for moderate-sized earthquakes, which are magnitudes 3-7.

How Earthquakes are Measured

• The scale ranges from 1 to 10, but includes measurements in fractions.
• It uses a seismograph to detect and record earthquakes, measuring seismic activity.
• Seismic activity is the movement of ground caused by rocks breaking underground.
• The seismograph calibrates the largest seismic wave and calculates the logarithm of its amplitude to determine magnitude.
• Accuracy is affected by proximity and the type of seismograph used.
• It is less accurate for earthquakes of magnitude 6.5 and higher.
• Each magnitude increase represents a 10-fold increase in ground shaking intensity.
• Each unit increase signifies about a 32-fold increase in energy released.
• An earthquake increasing from magnitude 4 to 8 increases in intensity by 1,048,576 times.

Moment Magnitude Scale

• The moment magnitude scale was developed in 1979 to complement the Richter scale.
• It can accurately measure highly destructive earthquakes with a magnitude of over 8.
• The Richter scale is more accurate for small to moderate earthquakes.
• The moment magnitude scale uses the seismic moment to determine its overall magnitude.
• Seismic moment is the force required to move a fault multiplied by the fault's displacement across the area.