In the last two hundred years, seismic activity in the San Francisco area has produced ____.
a. major earthquakes at intervals of about 60 years, with few smaller earthquakes
b. moderate (magnitude 6+) earthquakes every 10 to 15 years
c. moderate earthquakes every 10 to 15 years, and one major earthquake about 100 years ago
d. a cluster of moderate and major earthquakes in the early 1900s with a gap until recent moderate earthquakes
e. only major earthquakes
Question 2
The frequency-magnitude relationship predicts that any 100 km segment of the San Andreas Fault should experience an earthquake magnitude of 6 on average (enough to cause property damage) every ____ years.
a. 8
b. 80
c. 800
d. 8,000
e. 80,000