The Northern California earthquake of April 18, 1906, commonly referred to as the “Great San Francisco Earthquake of 1906", is the most damaging earthquake in US history. San Francisco and surrounding cities were violently shaken by seismic waves produced by the magnitude 7.9 earthquake. The remarkable post-earthquake construction and renaissance of the Bay Area are important events in the history of the region. The 1906 earthquake also revealed the existence and significance of the San Andreas fault to earth scientists, who then gave birth to the science of earthquakes. This virtual tour utilizes the geographic interactive software Google Earth to explain the scientific, engineering, and human dimensions of this earthquake, so as to help you visualize and understand the causes and effects of this and future earthquakes.
Global Geologic Setting of the 1906 Earthquake
The full significance of the horizontal slip on the San Andreas fault in 1906 would not be appreciated until the advent of plate tectonics more than half a century later. It is now known that the San Andreas fault accommodates most of the relative plate motion between the North American plate to the east and the Pacific plate to the west, about 1.5 inches/yr (4 cm/yr). This relative plate motion and the strain it imposes on the San Andreas fault was the cause of the 1906 earthquake and is the cause of earthquakes yet to come.
The San Andreas and Other Bay Area Faults
In the San Francisco Bay Area, the San Andreas fault is the principal member of a system of subparallel faults. Explore the San Andreas fault system in the Bay Area, together with the geology and seismic history prior to 1906.
The Northern California Earthquake, April 18, 1906
The 1906 earthquake initiated beneath the ocean just west of San Francisco and simultaneously ruptured the San Andreas fault to the northwest and southeast. The rupture has been traced 202 miles (325 km) to the northwest to near Cape Mendocino and 93 miles (241 km) to the southeast to near San Juan Bautista. Strong shaking was felt in the Bay Area for 45-60 seconds.
Historic Photographs of the 1906 Earthquake
The large number of photographs taken shortly after the 1906 earthquake are utilized by scientists to document surface rupture of the San Andreas fault and by engineers to document the extent and nature of damage to the built environment, including the liquefaction that occurred on the filled margins of San Francisco Bay.
Earthquake Hazards of the Bay Area Today
In 2006, the San Francisco Bay Area is a vastly different place from what it was 100 years ago. With a population of more than 7 million people dependent on a complex and vulnerable infrastructure the Bay Area is vulnerable to the effects of future earthquakes in the region. See the maps showing the densely urbanized parts of the Bay Area and maps of earthquake probabilities and liquefaction susceptibility.