Catastrophes! Earth-Shattering Events that Changed History

Earthquakes, tsunamis, volcanic eruptions, hurricanes, tornadoes, and other natural disasters remind us that, as Will Durant said, "Civilization exists by geologic consent, subject to change without notice." But despite the magnitude of these events, most people have a poor understanding of why they occur and what real dangers they pose-and what natural events are deadlier than even earthquakes.  The Bay Area Skeptics present this SKEPTALK by Dr. Donald Prothero, Professor of Geology at Occidental College.