TOEFL Listening: ETS-TOEFL听力机经 - 9UA33LK855A2QVKRP$

What does the professor say about earthquake activity below volcanoes? A. The earthquakes can be more destructive than volcanic eruptions. B. The earthquakes occur more frequently before volcanic eruptions begin. C. The earthquakes may reduce the severity of the next eruption. D. The earthquake tend to be difficult to detect.