Which scale is used to measure the strength of an earthquake? 

A)  the Miller scale 
B)  the Richter scale 
C)  the Mercalli scale 
D)  the Geiger scale

Richter Scale

A logarithmic scale used to measure the magnitude of earthquakes, based on the amplitude of seismic waves recorded on a seismograph.

Mercalli Scale

A scale that measures the intensity of an earthquake based on its observed effects on people, objects, and structures, rather than its energy.