The Role of Plate Tectonics

In Natural Disasters on the West Coast
On March 27, 1964 an earthquake shook Anchorage Alaska. It was 5:36 P.M. local time. The quake registered 8.6 on the Richter scale, although scientists now favor a different magnitude scale for very lage quakes that shows it at 9.2. This made it the largest quake that has hit the United States in recorded history, and second largest known worldwide. The earthquake started with a few seconds of small tremors. The tremors quickly developed into intense shaking that knocked people down, threw objects off shelves and caused buildings to collapse. Amazingly this shaking lasted for a full five minutes. People reported that it seemed like an eternity. The time of shaking generally increases with greater magnitude. The longer the ground shakes, the more damage will occur as structures first weaken and then collapse under the strain. The long period of shaking doubtless caused much of the ground failure that was observed from this quake. The widespread geological damage was impressive. …