seattle fault restoration point former sea cliff present...
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Restoration Point!
Restoration Point!
Former sea cliff!
Raised wave-cut
terrace!
Present terrace!
Seattle Fault!
Seattle fault uplift
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N-S contraction drives
uplift and basin formation
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-! =8!*2,9!'(>!*2359?&2#*!$0@*)!59*!82&/5!.!$A!59*3*!$&%5!92@*!'**+!-66!*@*+5%!(+!59*!/2%5!$(//(0+!1*23%<!
-! B9(%!($4/(*%!0+*!*@*+5!*@*31!-6A666!1*23%<!1 km
Restoration
Point
1998 trenches
1999 trenches
Mossy Lane
Toe Jam Hill fault scarp
12-ft lidar DEM
WEST POINT West Point Sewage Treatment Plant construction excavation
“Snags” in Lake Sammamish: 1100 years old
Conclusions
•! An event that would have had catastrophic
consequences occurred about 900 AD.
•! Individual faults have long recurrence times
(1000’s of years).
•! Many active faults are known and more are
being identified.
•! Jury still out on how often we can expect a
devastating crustal quake.