Major Ruptures

1989 Rupture

1989 Rupture
On October 17, 1989, at 5:04:15 p.m. (p.d.t.), a magnitude 6.9 earthquake severely shook the San Francisco and Monterey Bay regions. The epicenter was located near Loma Prieta peak in the Santa Cruz Mountains. The earthquake occurred when the Pacific and North American Plates abruptly slipped as much as 2 meters (7 ft) along their common boundary-the San Andreas fault system. The rupture initiated at a depth of 18 km (11 mi) and extended 35 km (22 mi) along the fault, but it did not break the surface of the Earth.
For more information: Loma Prieta Earthquake

1989 Rupture Extent

1906 Rupture

In the Great 1906 magnitude 7.8 earthquake, nearly 300 miles (480 Km) of the San Andreas Fault ruptured, producing strong shaking along all of coastal northern California. Shaking was most intense in Santa Rosa and San Francisco. In San Francisco, broken water mains kept firefighters from battling the fires that swept through the city and contributed to the devastation shown in the photograph below (looking south) taken from a tethered balloon 5 weeks after the earthquake.
For more information: 1906 Earthquake Centennial

1906 Rupture Extent

The magnitude 7.9 Fort Tejon earthquake in 1857 caused a horizontal shift of about 30 feet (9 m) on this stretch of the southern San Andreas Fault (red arrows indicate this "strike-slip" movement). Although the quake ruptured nearly 200 miles (300 km) of the fault, it did little damage because southern California’s population was small at that time.
For more information: Fort Tejon Earthquake

1857 Rupture Extent

In this computer simulation, tsunami waves are radiating outward after a magnitude 9 earthquake that occurred on the Cascadia Subduction Zone offshore of northern California, Oregon and Washington on January 26, 1700. This view shows the waves 4 hours after the quake. Colors indicate wave heights—red is highest. Along parts of the coast of the Pacific Northwest, 30-foot-high (9 m) waves rushed inland. Within 20 hours the tsunami did damage throughout the Pacific, and it is well documented in written records from Japan.
For more information: Tsunami, USGS or Orphan Tsunami

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