<br><font size=2 face="sans-serif">After rereading the last paragraph in
the ScienceNOW article several times, I agree with Sue. Stein's point is
about the occurrence of earthquakes somewhere that are larger than any
in the historical and paleoseismic records of that area. In such a case,
as in Haiti, Wenchuan, and Tohoku, a pertinent question is whether the
most recent probabilistic hazard assessment of the area assumed the
possibility of an earthquake at least as large as the big recent earthquake
there. Since at least 1996 the CEUS parts of the USGS hazard maps have
used Mmax values big enough that there have been no nasty surprises, either
in the CEUS itself, in tectonically analogous areas worldwide, or in the
sparse but growing paleoseismic record. Whether those CEUS values are really
big enough to be Mmax we don't yet know how to tell. Actually we do know
how to tell, but the approach is not particularly helpful: wait ten thousand
years or so.</font>
<br>
<br><font size=2 face="sans-serif">Rus Wheeler<br>
-----------------------------------------<br>
Rus Wheeler<br>
research geologist<br>
phone: (303) 273-8589<br>
fax: (303) 273-8600<br>
email: wheeler@usgs.gov<br>
<br>
paper mail:<br>
Russell L. Wheeler<br>
U.S. Geological Survey<br>
P.O. Box 25046, M.S. 966<br>
Lakewood, CO 80225<br>
<br>
physical address, FedEx, UPS:<br>
1711 Illinois St., rm. 442<br>
Golden, CO 80401</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">From:</font>
<td><font size=1 face="sans-serif">"Susan Hough" <hough@gps.caltech.edu></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">To:</font>
<td><font size=1 face="sans-serif">"Central and Eastern U.S. Earthquake
Hazards Listserve" <ceus-earthquake-hazards@geohazards.usgs.gov></font>
<tr>
<td valign=top><font size=1 color=#5f5f5f face="sans-serif">Cc:</font>
<td><font size=1 face="sans-serif">"Central and Eastern U.S. Earthquake
Hazards Listserve" <ceus-earthquake-hazards@geohazards.usgs.gov></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Date:</font>
<td><font size=1 face="sans-serif">04/29/2011 05:37 AM</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Subject:</font>
<td><font size=1 face="sans-serif">Re: [CEUS-earthquake-hazards] Article
on Central U.S. Earthquake hazard by expert panel</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Sent by:</font>
<td><font size=1 face="sans-serif">ceus-earthquake-hazards-bounces@geohazards.usgs.gov</font></table>
<br>
<hr noshade>
<br>
<br>
<br><tt><font size=2>I read and reread the ScienceNOW article looking for
the word<br>
"prediction," having seen Rus' comment before I read the article.
Seems<br>
to me clear that Seth was commenting on the reliance on observed<br>
seismicity alone to constrain hazard maps. I'm sure he talked to Kerr at<br>
some length -- as always only a sound-bite makes it into a short article.<br>
Rus' point is well taken: no one earthquake is a "failure" of
a hazard<br>
map, unless maybe the earthquake exceeds an Mmax value that was assumed
in<br>
generating the map. More generally, though, I think the main point
Seth<br>
was making has been underscored by the quakes he mentioned. I've
made<br>
this exact same argument in my own talks (most recently this evening),<br>
usually by way of making the point that the short historical record can<br>
lull people into a false sense of security. But clearly it can go
the<br>
other way sometimes. I.e., just thinking conceptually, there must
be<br>
areas that have been more active in the historic (or known prehistoric)<br>
record than the average long-term rates.<br>
<br>
Sue Hough<br>
<br>
<br>
<br>
> The probabilistic methods that the USGS and other organizations use
to<br>
> estimate hazard are not predictions. Instead, the methods give estimates<br>
> of the strength of shaking that we'd expect (at specified odds) to
be<br>
> exceeded in the next 50 years at some particular place. The
specified<br>
> odds are usually about one in ten or one in fifty. If a particular
place<br>
> is shaken at or above the estimated level, the cause could be either
a big<br>
> earthquake far away, or a smaller one nearby. Also, the expected shaking<br>
> could occur at any time from tomorrow to 50 years from now...or not
at<br>
> all, if it beats the odds. Nothing in a probabilistic hazard estimate<br>
> specifies the size, time, and location of the next big earthquake.<br>
><br>
> Making a prediction and estimating the hazard are fundamentally different<br>
> in purposes, assumptions, calculations, results, and uses. A failure
to<br>
> get either of them right has no bearing on the validity of the other
one.<br>
> -----------------------------------------<br>
> Rus Wheeler<br>
> research geologist<br>
> phone: (303) 273-8589<br>
> fax: (303) 273-8600<br>
> email: wheeler@usgs.gov<br>
><br>
> paper mail:<br>
> Russell L. Wheeler<br>
> U.S. Geological Survey<br>
> P.O. Box 25046, M.S. 966<br>
> Lakewood, CO 80225<br>
><br>
> physical address, FedEx, UPS:<br>
> 1711 Illinois St., rm. 442<br>
> Golden, CO 80401<br>
><br>
><br>
><br>
> From:<br>
> Oliver Boyd <olboyd@usgs.gov><br>
> To:<br>
> "ceus-earthquake-hazards@geohazards.usgs.gov"<br>
> <ceus-earthquake-hazards@geohazards.usgs.gov><br>
> Date:<br>
> 04/27/2011 10:09 AM<br>
> Subject:<br>
> [CEUS-earthquake-hazards] Article on Central U.S. Earthquake hazard
by<br>
> expert panel<br>
> Sent by:<br>
> ceus-earthquake-hazards-bounces@geohazards.usgs.gov<br>
><br>
><br>
><br>
> Dear CEUS earthquake hazards email list subscribers,<br>
> Below is a link to a short article about the findings of a National<br>
> Earthquake Prediction Evaluation Council expert panel regarding central<br>
> United States earthquake hazard.<br>
><br>
> </font></tt><a href="http://news.sciencemag.org/sciencenow/2011/04/expert-panel-central-us-faces.html"><tt><font size=2>http://news.sciencemag.org/sciencenow/2011/04/expert-panel-central-us-faces.html</font></tt></a><tt><font size=2><br>
><br>
><br>
> Regards,<br>
> Oliver<br>
><br>
> --<br>
><br>
> Oliver Boyd, Ph.D.<br>
> Research Geophysicist<br>
> U.S. Geological Survey<br>
> 3876 Central Ave<br>
> Memphis, TN<br>
> Phone: (901) 678-3463<br>
> FAX: (901) 678-4897_______________________________________________<br>
> CEUS-Earthquake-Hazards mailing list<br>
> CEUS-Earthquake-Hazards@geohazards.usgs.gov<br>
> </font></tt><a href="https://geohazards.usgs.gov/mailman/listinfo/ceus-earthquake-hazards"><tt><font size=2>https://geohazards.usgs.gov/mailman/listinfo/ceus-earthquake-hazards</font></tt></a><tt><font size=2><br>
><br>
><br>
> _______________________________________________<br>
> CEUS-Earthquake-Hazards mailing list<br>
> CEUS-Earthquake-Hazards@geohazards.usgs.gov<br>
> </font></tt><a href="https://geohazards.usgs.gov/mailman/listinfo/ceus-earthquake-hazards"><tt><font size=2>https://geohazards.usgs.gov/mailman/listinfo/ceus-earthquake-hazards</font></tt></a><tt><font size=2><br>
><br>
<br>
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CEUS-Earthquake-Hazards@geohazards.usgs.gov<br>
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