[PNW-Earthquake-Hazards] Info on the Boulder Creek Fault, PNW Fault Working Group

[Joan S Gomberg]

All,
Below is an AGU abstract contributed by Elizabeth Barnett on the Boulder 
Creek fault (Kendall Scarp); she also says that she'd provide figures of 
location maps, trench logs, and LiDAR if they'd be helpful.  Please let me 
know, or send the email to the listserve (
pnw-earthquake-hazards at geohazards.cr.usgs.gov), if you'd like more 
information from her.
Thanks Elizabeth and Happy New Year All!
Joan

Paleoseismic trenching studies document an active east-west trending fault
located at the northeast margin of the Puget Lowland, approximately 35 km
northeast of Bellingham, Washington. Thrust faulting of Late Pleistocene 
glacial
outwash sediments over Holocene soils produced the south-side up Kendall 
scarp,
initially revealed by LiDAR surveys of the North Fork of the Nooksack 
River. Trenching
and coring of adjacent wetlands suggest a minimum of one folding event and 
two
surface-rupturing earthquakes along the Kendall scarp fault within the 
latter half of
the Holocene with combined vertical offset of at least two meters. Dated 
organic
material from buried soils within the wetlands and trenches suggest 
possible dates
of between ~7700-3200 yrs BP for the folding event and ~3200 yr BP and 
~1000 yr BP
for the two surface-rupture events. Mazama ash from the base of the 
wetlands cores
provides a maximum age for all faulting events recorded in the trenches 
and
wetlands of ~7700 yr BP.

Joan Gomberg
US Geological Survey
University of Washington
Dept of Earth and Space Sciences, Box 351310
Seattle, Washington 98195-1310
206-616-5581(office) 
206-553-8350 (fax)
206-941-7498 (cell)
gomberg at usgs.gov
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