Chief Seattle

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reportedly canoed out to meet Capt. Vancouver
and the ships Discovery and Chatham in May 1792.
Duwamish Tribe finally recognized 19 Jan. 2001
Chief Seattle
downtown Seattle, 1995
first plats filed in 1853 1880-1890 12x
increase in population (1888 -1889 25,000 to
43,000) 29 city blocks burned in 1889
current metro population 3.2 million (15th in
U.S.)
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Geological Environment Puget Sound Lowlands
between Olympic and Cascade Mtns. tectonically
unstable / Cascadia subduction zone glacial
tills and outwash overlie andesite volcanic
bedrock glacial sediments up to 3500 feet
thick Physiography several hundred feet of
relief numerous lakes and marine channels
over-consolidated till Geological Hazards
landslides earthquakes (magnitude 9 about
1700) tsunami peri-volcanic hazards
mudflows and ash mine subsidence Limitations
lakes and marine bays shallow water
table steep topography in many areas
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Esperance Sand
Lawton Clay
Discovery Bay Sand
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deeply eroded, but apparently stable slope above
the shore of Puget Sound
Slope failure at the Lawton (base) Esperance
(top) contact
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Recent mudflows from 14,410 ft. Mt. Rainier.
Seattle lies just north of Kent many of
Seattles southern suburbs rest on mudflow
deposits. The photo above shows a very recent
mudflow from Mt. St. Helens.
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Seattle Earthquake of 2001.flv
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• 16571777 (28). there was a big flood shortly
  before the white mans time, a huge tidal wave
  that struck the Oregon Coast not too far back in
  time the ocean rose up and huge waves swept and
  surged across the land. Trees were uprooted and
  villages were swept away. Indians said they tied
  their canoes to the top of the trees, and some
  canoes were torn loose and swept away After the
  tidal wave, the Indians told of tree tops filled
  with limbs and trash and of finding strange
  canues in the woods. The Indians said the big
  flood and tidal wave tore up the land and changed
  the rivers. Nobody knows how many Indians died.
  Beverly Ward, recounting stories told to her
  around
• 1930 by Susan Ned, born in 1842.

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Dead trees - carbon dated at 1700 AD and engulfed
by tsunami deposits
Lake Sammamish trees are submerged and the
development seen in this photo rests on landslide
deposits
Seattle fault inferred from abrupt difference in
the thickness of over-consolidated till
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from USGS and Bourgeois, and Johnson. 2001 GSA
Bulletin Vol.113, p. 482-494
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downtown Seattle (Denny Regrade 1) in 1910 and
then in 1928 and finally in 1931. Sediments
removed by hydraulic sluicing were deposited in
tidal marshes of Duwamish Bay, now part of the
marine port and SeaTac Airport. Would this be
permitted under the King Co. Sensitive Areas
Ordinance?
1910
1928
2006
1931
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tie-back anchors being installed, 1982 (photo by
T. Gurtowaski)
shotcrete application above the Seattle marina
(under construction) (photo by R. Galster, 1990)
1995
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Lake Washington floating bridge a new span was
added in 1989 and the old span refurbished
(western end of I-90)
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Lake Washington Bridge float-style
construction lake is up to 200 ft. deep 5
55 feet of peat, up to 100 ft. soft clay
channel is 1.25 miles wide accommodates 2-4
ft. lake level variation 75 ton concrete
anchors jetted down to solid ground 1939,
refurbished in 1963, twin span finished in
1989 Lake Union Ship Canal 1911- 1916
connected Lks. Washington, Union Puget Sound
lowered Lake Washington by 20 feet Cedar R.
diverted into Lake Washington planned
Pittsburgh of the West