The Richter scale measures how much the ground shakes in an earthquake. Note that this is not equal to the energy released by an earthquake. However, there is a simple relationship between Richter magnitude and earthquake energy.

A 1-point increase on the Richter scale corresponds to an energy increase of about 30 times. Thus a 5.0-magnitude earthquake releases about 30 times as much energy as a 4.0-magnitude earthquake. The 5.0-magnitude earthquake releases about 900 (30 х 30) times the energy of a 3.0-magnitude quake.

(a) How much more energy does an 8.0-magnitude earthquake release than a 7.0-magnitude earthquake?

(b)How much more energy does a 7.0-magnitude earthquake release than a 5.0-magnitude earthquake?

(c) How much more energy does a 7.0-magnitude earthquake release than a 4.0-magnitude earthquake?

(d) How much less energy does a 6.0-magnitude earthquake release than a 7.0-earthquake?