1.
Modern wave cut platform being actively carved out of
solid bedrock at Alki Point in West Seattle. Concrete
sea wall at right covers up small bedrock cliff. Houses
on other side sit on old wave cut platform uplifted 1100
years ago during a large earthquake event.
2. House on top of seastack carved out of solid bedrock.
We're standing on the uplifted wavecut platform.
Dig under the grass and you'll find beach sand.
3. Tilted layers of 40,000 year old peat and mud deposits.
The tilting must have occurred within the last 40,000 years,
and may be related to movement on the Seattle Fault.
Picture taken at Meek-Wa-Mooks park south of Alki Point.
4. Over to Bainbridge Island to look at the Toe Jam Hill Fault.
Brian Sherrod and Alan Nelson hold their poster of the LIDAR
imagery (top) and trench results (bottom) for the Toe Jam Hill
fault. The red laser dot rests on the trace of the fault.
5. This road on the west side of Bainbridge Island is built
on an uplifted marine terrace, probably 2000 years old or so.
There are a series of terraces marching up the hillside here,
including a lower terrace uplifted 1100 years ago.
6. The Seattle fault on Bainbridge Island, trenched to
reveal details of the fault and its movement history.
Too dark to show any details unfortunately, but gives you a
feel for what the geologists have to work with.
7. The Waterman fault on the Kitsap Peninsula south of Bainbridge
Island shows up on this LIDAR image as the prominent line
running east west across the map. The Glover Point fault can
be seen near the north tip of the peninsula.
8. Results of trenching the Waterman Point fault. The red
lines
are faults cutting various materials.
9. The fault scarp associated with the Waterman Fault. The
fault
runs left to right through the cluster of people on the road. Our
side has moved up and over their side.
10. Standing on the fault scarp looking parallel/along the
fault. The house in the background left (with red truck)
is built right at the foot of the fault scarp.
11. The west end of the Waterman Fault at the little cove
(see slide # 8 for location). The fault runs through the cove
(left-right) where the people are clustering. We're standing on
an uplifted terrace, and the houses are on a terrace too,
but they're higher than we are. The block on the other side
of the fault from us is moving up and towards us, breaking the
terrace in half.
12. Fault scarp associated with recent movement on the Tacoma
Fault, on the Kitsap Peninsula. What would we do without LIDAR?
13. Lynch Cove at the very north end of Hood Canal, near
the town of Belfair. Hood Canal is shaped like a fishhook, and
we're
at the very end. Giant mudflats now drained by ditches and
colonized with vegetation. The mudflats have also been uplifted
during earthquakes.
14. Carrie Garrison-Laney of the USGS in one of the drainage
ditches. The ditches provide great cross sections through the
good stuff that has accumulated in this tidal marsh.
15. From bottom to top: A, ugly mud with white shells,
B gray tsunami deposit of sand and mud, C dark brown to
black peat with some red staining, D a thin and irregular
tsunami? layer and E more brown red peat. The tsunami
deposit on top of the shells is about 1100 years old.
