Why do earthquakes and volcanic eruptions frequently occur in the same areas?

Long ago, people who lived in coastal north africa most often interacted with

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

Which of the following statements best explains why there tends to be a greater number of large cities in southern africa than the east africa