Puget Sound faults about 1100 years ago (AD 900—930) an earthquake of magnitude 7+ uplifted Restoration Point and Alki Point, dropped West Point (the three white triangles in the Seattle Basin on the map), caused rockslides in the Olympics, landslides into Lake Washington, and a tsunami on Puget Sound. It extends as far east as (and probably terminates at) the Rattlesnake Mountain Fault Zone (RMFZ; the southern extension of the SWIF) near Fall City. This seems geologically reasonable, as both the SWIF and RMFZ appear to be the contact between Tertiary Crescent Formation basement of Puget Sound on the west and the older
South Puget Sound South Puget Sound South Puget Sound is the southern reaches of Puget Sound in Southwest Washington, in the United States' Pacific Northwest. It is one of five major basins encompassing the entire Sound, and the shallowest basin, with a mean depth of . Exact definitions of the region vary: the state's Department of Fish and Wildlife counts all of Puget Sound south of the Tacoma Narrows for fishing regulatory purposes. The same agency counts Mason, Jefferson, Kitsap, Pierce and Thurston Counties for wildlife management. The state's Department of Ecology defines a similar area south of Colvos Passage. The term "South