Exam 3: Earthquakes and Their Causes

A ____ fault would be expected at a divergent boundary.

Stresses cause rocks to deform; earthquakes occur as the rock can no longer deform and ruptures.

Rock deformation is referred to as ____.

The atomic bomb dropped on the city of Hiroshima, Japan at the close of World War II ("Little Boy") released energy equivalent to 15 kT (about 15 million kilograms of explosive). The largest nuclear weapon ever tested was a 50 MT (about 50 billion kilograms of explosive) weapon ("Tsar Bomba") developed by the Soviet Union in 1961. ​ Discuss the magnitude of an earthquake required to produce energy equivalent to each weapon, the frequency at which such earthquake occur, and differences you might expect in the way nuclear weapons and earthquakes cause harm to a population. Refer to Figure 3-28 in your text, which illustrates t he average number of earthquakes per year, worldwide, and a comparison of the amount of energy they expend.

What is the most critical factor affecting the moment magnitude of an earthquake?

How many separate sites of seismograph recordings are required to locate the center of an earthquake?

Rock layers that are very susceptible to brittle failure would be expected to produce ____.

The first earthquake waves received by a seismograph near the epicenter are P waves.

The distance to the epicenter is determined by the time delay between the arrival of P and S waves.

Using the Richter magnitude scale, the amplitude of motion in a 7.0 magnitude earthquake is ____ times the motion in a 5.0 magnitude earthquake.