April 18, 1906 Tsunami: N. California, United States

A catastrophic earthquake on the San Andreas fault resulted in a fire that destroyed most of San Francisco and killed 700 to 800 people. Magnitude values have ranged from 7.8 to 8.5. The rupture produced up to twenty feet of right lateral horizontal motion with the Pacific plate moving northward. Many landslides occured along the coast, from Cape Mendocino to Point Delgado. A four inch drop in water level was recorded seven to nine minutes after the earthquake on the Fort Point tide record, which returned to normal in about 15 minutes. There were several cycles of forty minute waves followed by what were probably seiches in the bay. None of these would be noticeable to an observer (Reference #237).

Everywhere on the high steep coast from Mendosino Cape to Cabo Delgada, on a stretch of many kilometers, slopes collapsed into the sea. On the lower coast between Shelter Cove and Point Arena, bedrocks and loose material slipped into the sea, and the water was turbid for several days after the earthquake...In the region of Bolinas Bay and to the north, the eastern flank subsided relatively 0.3-0.6 m (1-2 feet). Apparently, one of the flanks of the fault [the eastern?] subsided slightly under the water as well. After this disturbance, the tide gauge record shows oscillations with a period of about 40 minutes, which is equal to the period of the transverse seiches of San Francisco Bay (Reference #415).