<br><font size=2 face="sans-serif">Another clarification: In addition
to the risk coefficients mentioned below, there are "maximum direction"
amplification factors of 1.1 and 1.3 for, respectively, 0.2- and 1.0-second
spectral acceleration that are applied to the 2008 USGS hazard maps in
deriving updated design maps for building codes. Furthermore, the
2008 hazard maps themselves are different than the 2002 (and 1996) hazard
maps, as are the corresponding deterministic "caps" that are
applied to the respective hazard maps. Thus, the updated design maps
based on the 2008 hazard maps are not simply lower than previous design
maps by a factor of 0.7 near New Madrid and Charleston. In fact,
in some cases the new design map values may be about the same as the previous
ones.</font>
<br>
<br><font size=2 face="sans-serif">Again, please let me know if you have
any questions/comments </font>
<br>
<br><font size=2 face="sans-serif">----------------------------------------------------------------------------<br>
Nicolas Luco<br>
Research Structural Engineer<br>
U.S. Geological Survey<br>
<br>
Mailing Address:<br>
PO Box 25046, MS 966<br>
Denver, CO 80225<br>
<br>
Physical/Overnight Address:<br>
1711 Illinois Street, Room 426<br>
Golden, CO 80401<br>
<br>
Phone: (303)273-8683<br>
Fax: (303)273-8600<br>
----------------------------------------------------------------------------</font>
<br>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td width=40%><font size=1 face="sans-serif"><b>Seth Stein <seth@earth.northwestern.edu></b>
</font>
<br><font size=1 face="sans-serif">Sent by: ceus-earthquake-hazards-bounces@geohazards.usgs.gov</font>
<p><font size=1 face="sans-serif">01/14/2009 12:13 PM</font>
<table border>
<tr valign=top>
<td bgcolor=white>
<div align=center><font size=1 face="sans-serif">Please respond to<br>
"Central and Eastern U.S. Earthquake Hazards Listserve"
<ceus-earthquake-hazards@geohazards.usgs.gov></font></div></table>
<br>
<td width=59%>
<table width=100%>
<tr valign=top>
<td>
<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif">"ceus-earthquake-hazards@geohazards.usgs.gov"
<ceus-earthquake-hazards@geohazards.usgs.gov></font>
<tr valign=top>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td>
<tr valign=top>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">[CEUS-earthquake-hazards] Revised seismic
design criteria for New Madrid</font></table>
<br>
<table>
<tr valign=top>
<td>
<td></table>
<br></table>
<br>
<br>
<br><tt><font size=2>Readers may be interested in the latest proposal for
seismic building<br>
design criteria. In it "the 2008 USGS hazard maps should not be<br>
substituted for the model building code design maps nor should they be<br>
used with ASCE/SEI 41 or 31 for seismic rehabilitation or evaluation."<br>
<br>
Specifically, there are a set of scale (risk) factors to apply to the<br>
2008 USGS hazard maps to produce design maps: "Resulting risk<br>
coefficients are generally 0.85-1.15, but as low as 0.7 near New Madrid<br>
and Charleston".<br>
<br>
The USGS disclaimer<br>
<br>
http://earthquake.usgs.gov/research/hazmaps/products_data/2008/disclaimer.php
<br>
<br>
<br>
gives information about how the hazard maps are modified to<br>
produce design maps. For additional information, see<br>
<br>
http://bssconline.org/2008AnnualMeeting/080910--Luco1@BSSC_Annual_Mtg(Posted).pdf<br>
http://bssconline.org/2008AnnualMeeting/08MeetingRecap.html<br>
-- <br>
Seth Stein<br>
William Deering Professor<br>
Department of Earth and Planetary Sciences<br>
1850 Campus Drive<br>
Northwestern University, Evanston, IL 60208<br>
(847) 491-5265 FAX: (847) 491-8060 E-MAIL: seth@earth.northwestern.edu<br>
http://www.earth.northwestern.edu/people/seth<br>
<br>
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CEUS-Earthquake-Hazards@geohazards.usgs.gov<br>
https://geohazards.usgs.gov/mailman/listinfo/ceus-earthquake-hazards<br>
</font></tt>
<br>