Today is the centennial of the great San Francisco earthquake and fire of 1906, which killed at least 700 (perhaps many more), and was one of the first earthquakes to be the subject of intense scientific study. The San Andreas fault had displacement along 477 km of its length, compared to the 40 km displacement zone that caused the 1989 Loma Prieta “World Series” earthquake. The magnitude of the earthquake is estimated to have been between 7.7 and 8.3.

2.5 m horizontal displacement along the San Andreas fault in April, 1906. How this magnitude of horizontal displacement could have occurred was not understood until the advent of the theory of plate tectonics in the 1960s. Image from the USGS.

Map comparing the portion of the San Andreas fault affected by the 1906 and 1989 earthquakes, also from the USGS. The portion of the San Andreas fault extending southward past Los Angeles to the Gulf of California was unaffected by these earthquakes.

Louis Agassiz was the founder of the science of glacial geology, but his statue at Stanford University did not fare too well in the earthquake.