<br><font size=3 face="sans-serif">PNW Fault Working Group,</font>
<br>
<br><font size=3 face="sans-serif">I'd like to propose a conference call
meeting for 1/16 at 10:00 am PST to discuss the possible changes to the
PNW National Maps suggested in previous emails (listed below FYI). If
you are still intending to supply information to facilitate this (Craig,
Brian, Elizabeth), and this date is too soon, please let us know asap.
Similarly if this date or time does not work for you, please let
me know. </font>
<br>
<br><font size=3 face="sans-serif">Thanks and happy holidays!</font>
<br><font size=3 face="sans-serif">Joan</font>
<br>
<br><font size=3 face="sans-serif">New additions: <br>
<br>
The Stonewall anticline (Newport, OR) <br>
This has been suggested by Bob Yeats and is discussed by he and Rus <br>
Wheeler in the attachments.<br>
<br>
More faults in Yakima fold belt <br>
This has been suggested by Bob Yeats and is discussed by he and Rus <br>
Wheeler in the attachments.<br>
<br>
Boulder Creek fault (has multiple events with age constraints)<br>
Brian Sherrod has new information to share. <br>
<br>
Little River fault (has multiple events with age constraints) <br>
See presentation under "Faults in the Puget Sound region and elsewherein
<br>
western Washington" by Alan Nelson. <br>
<br>
<br>
Slip rate changes: <br>
<br>
Portland Hills fault <br>
Change slip rate from 0.1 mm/yr (in 2002 maps) to 0.07 mm/yr; proposed
by <br>
Ian Madin <br>
<br>
Bolton fault <br>
Change slip rate from 0.013 mm/yr (in 2002 maps) to 0.015 mm/yr; proposed
<br>
by Ian Madin <br>
<br>
Mt Angel fault <br>
There is new information, noted by Bob Yeats and and discussed by he and
<br>
Rus Wheeler in the attachments, but it is not clear that any change is
<br>
being advocated in the treatment of this fault. <br>
<br>
SWIF <br>
Change fault geometry and dimensions; see Art?s Introductory presentation
<br>
that notes a change dip from 60 to 45 degrees,seismogenic layer thickness
<br>
from 17.3 to 20 km, length from 63 to 86 km. Assuming the same uplift
<br>
rate of 0.6 mm/yr this changes the characteristic magnitude from M7.2 to
<br>
M7.3 with Tchar from 3100 to 1700 yr, and for a M6.5 the recurrence time
<br>
changes from 930 to 400 yr. For 0.5 mm/yr strike slip component (derived
<br>
assuming pure north-south convergence): Tchar=2900 yr and the recurrence
<br>
time for a M 6.5 becomes 680 yr. Combining these equally (1/2 reverse
and <br>
1/2 strike-slip motion) results in Tchar= 1300 yr and a M 6.5 recurrence
<br>
interval of 310 yr, which are much shorter times than used for the Seattle
<br>
fault.<br>
Also see presentations under "South Whidbey Island Fault experience"
by <br>
Rick Blakely <br>
</font>
<br>
<br><font size=2 face="sans-serif">Joan Gomberg<br>
US Geological Survey<br>
University of Washington<br>
Dept of Earth and Space Sciences, Box 351310<br>
Seattle, Washington 98195-1310<br>
206-616-5581(office) <br>
206-553-8350 (fax)<br>
206-941-7498 (cell)<br>
gomberg@usgs.gov</font>