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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Art,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Your response to our comment (Wang and
others, 2005) was on the ground motion from a single M7.7 New Madrid earthquake
with 500 years recurrence interval (an 1811-12 type earthquake). <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>I agree with you that “as you design buildings to
ground motions with lower probability levels, you are protecting a larger
fraction of buildings from the range of ground motions expected during the
next 1811-12 type earthquake.” This is the basic in decision
making. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>But my question is what are the probability levels (or confidence
levels), 0%, 50%, or 80%, on the national ground motion hazard maps (with 500,
1,000, 2,500 years return periods)? Engineers and policy-makers can make their decisions
if the probability levels are known.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Thanks.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Zhenming <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Arthur D Frankel
[mailto:afrankel@usgs.gov] <br>
<b><span style='font-weight:bold'>Sent:</span></b> Tuesday, February 19, 2008
11:01 PM<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">Wang,
Zhenming</st1:PersonName><br>
<b><span style='font-weight:bold'>Cc:</span></b> <st1:PersonName w:st="on">ceus-earthquake-hazards@geohazards.usgs.gov</st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> Re:
[CEUS-earthquake-hazards] FW: reply to Joe Tomasello; buildings codes and
earthquake hazard</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Zhenming,<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> <o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> These two statements are not contradictory,
when taken in the context that I wrote them.<o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> <o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> In the quote from my response to my comment,
I was referring to the ground motions observed at any given location over time.
At any particular site the ground motions with a 2% chance of being exceeded in
50 years, will occur, on average, once in 2500 years. As I said before, another
way to express this is that these ground motions have a 1/2500 chance of
being exceed each year.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> <o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> The point of my recent email is that each
time an 1811-12 type earthquake occurs, there will be some locations that will
experience the 2%/50 ground motions or larger, because of the spatial
variability of ground motions. The set of sites that experience these
higher ground motions will likely be different for each occurrence of this type
of earthquake, because of the variability of ground motions from earthquake to
earthquake. This apparent temporal variability of ground motions will occur
even for successive earthquakes on the same fault, because of differences in
rupture propagation and slip on the fault from earthquake to earthquake. <o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> <o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>As you design buildings to ground motions with lower
probability levels, you are protecting a larger fraction of buildings from the
range of ground motions expected during the next 1811-12 type earthquake.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Art Frankel<br>
<st1:country-region w:st="on"><st1:place w:st="on">U.S.</st1:place></st1:country-region> Geological Survey<br>
MS 966, Box 25046<br>
DFC<br>
<st1:place w:st="on"><st1:City w:st="on">Denver</st1:City>, <st1:State
w:st="on">CO</st1:State> <st1:PostalCode w:st="on">80225</st1:PostalCode></st1:place><br>
phone: 303-273-8556<br>
fax: 303-273-8600<br>
email: <a href="mailto:afrankel@usgs.gov" target=blank>afrankel@usgs.gov</a><o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color="#990099"
face=Verdana><span style='font-size:10.0pt;font-family:Verdana;color:#990099'>-----ceus-earthquake-hazards-bounces@geohazards.usgs.gov
wrote: -----</span></font><font size=2 face=Verdana><span style='font-size:
10.0pt;font-family:Verdana'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>To: "<st1:PersonName w:st="on">ceus-earthquake-hazards@geohazards.usgs.gov</st1:PersonName>"
<<st1:PersonName w:st="on">ceus-earthquake-hazards@geohazards.usgs.gov</st1:PersonName>><br>
From: "<st1:PersonName w:st="on">Wang, Zhenming</st1:PersonName>"
<zmwang@email.uky.edu><br>
Sent by: ceus-earthquake-hazards-bounces@geohazards.usgs.gov<br>
Date: 02/19/2008 07:34AM<br>
Subject: [CEUS-earthquake-hazards] FW: reply to Joe Tomasello; buildings codes
and earthquake hazard<br>
<br>
<br>
<o:p></o:p></span></font></p>
<O:SMARTTAGTYPE SmartTagTypenamespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PostalCode" downloadurl="http://www.5iamas-microsoft-com:office:smarttags"><!-- /* Font Definitions */ @font-face{font-family:Tahoma;panose-1:2 11 6 4 3 5 4 4 2 4;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal{margin:0in;margin-bottom:.0001pt;font-size:12.0pt;font-family:"Times New Roman";}a:link, span.MsoHyperlink{color:blue;text-decoration:underline;}a:visited, span.MsoHyperlinkFollowed{color:purple;text-decoration:underline;}p{mso-margin-top-alt:auto;margin-right:0in;mso-margin-bottom-alt:auto;margin-left:0in;font-size:12.0pt;font-family:"Times New Roman";}span.EmailStyle18{mso-style-type:personal-reply;font-family:Arial;color:navy;}@page Section1{size:8.5in 11.0in;margin:1.0in 1.25in 1.0in 1.25in;}div.Section1{page:Section1;}-->
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Here is another inconsistent statement on the national seismic
hazard maps.<u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 color=navy face="Times New Roman"><span style='font-size:12.0pt;
color:navy'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 color=navy face="Times New Roman"><span style='font-size:12.0pt;
color:navy'>“ </span></font>You have the mistaken notion that 2%/50
values are only observed once in 2500 years. This is flat out wrong. <font
color=navy><span style='color:navy'>” <u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 color=navy face="Times New Roman"><span style='font-size:12.0pt;
color:navy'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 color=navy face="Times New Roman"><span style='font-size:12.0pt;
color:navy'>In a response to our comment (Wang and others, 2005) that was
published on Seismological Research Letter (Frankel, 2005), the interpretation
was “the ground motion with 2% PE in 50 years is exceeded once, on
average over 2,500 years, so that it has a 1/2500 annual probability of being
exceeded.” <u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 color=navy face="Times New Roman"><span style='font-size:12.0pt;
color:navy'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 color=navy face="Times New Roman"><span style='font-size:12.0pt;
color:navy'> <img border=0 width=619 height=464 id="_x0000_i1026"
src="cid:image001.gif@01C8739F.F251CAA0"></span></font><o:p></o:p></p>
<u1:p></u1:p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>As demonstrated earlier, for a single M7.7 earthquake with 500 year
recurrence interval in the New Madrid seismic zone, ground motion with
2,500-year return period (2% PE in 50 years) means there is about 20 percent
probability that ground motion will be exceeded if the M7.7 earthquake occurs.
In other words, if the ground motion with 2,500-year return period is selected
for engineering design, we has a confidence level of 80% (not being exceeded)
if the M7.7 earthquake occurs. <u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Thanks. <u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><u1:p> </u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Zhenming <u1:p></u1:p></span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><u1:p> </u1:p></span></font><o:p></o:p></p>
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face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
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<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;font-weight:
bold'>From: </span></font></b><font size=2 face=Tahoma><span style='font-size:
10.0pt;font-family:Tahoma'>ceus-earthquake-hazards-bounces@geohazards.usgs.gov
[mailto:ceus-earthquake-hazards-bounces@geohazards.usgs.gov] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Arthur D Frankel <br>
<b><span style='font-weight:bold'>Sent: </span></b>Friday, February 15, 2008
1:50 PM <br>
<b><span style='font-weight:bold'>To: </span></b>Joe Tomasello <br>
<b><span style='font-weight:bold'>Cc: </span></b><st1:PersonName w:st="on">ceus-earthquake-hazards@geohazards.usgs.gov</st1:PersonName>;
mpetersen@usgs.gov <br>
<b><span style='font-weight:bold'>Subject: </span></b>Re:
[CEUS-earthquake-hazards] reply to Joe Tomasello; buildings codes and
earthquake hazard </span></font><u1:p></u1:p><o:p></o:p></p>
</div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'><u1:p> </u1:p><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'><br>
Joe, <br>
<br>
I feel I need to reply to you on the bulletin board, since you seem to
want to keep this discussion going and you directly ask me questions. My
apologies to Paul Segal and others who are fed up with this. <br>
<br>
I guess you missed one of the key points of my previous email. I
said that the IBC values (2/3 times the ground motions with 2% probability of
exceedance in 50 years [2%/50]) were probably experienced in<st1:city u2:st="on"><st1:place u2:st="on">Memphis
</st1:place>during the 1811-12 earthquakes, based on intensity data from those
earthquakes. <br>
<br>
You have this mistaken notion that IBC values (2/3 times the 2%/50
motions) are only observed once in a millenium. You have the
mistaken notion that 2%/50 values are only observed once in 2500 years. This is
flat out wrong. Some locations will experience 2/3 times the 2%/50
ground motions during the next 1811-12 type earthquake. Some locations
will experience the 2%/50 ground motions during the next 1811-12 type
earthquake. This is a simple consequence of the observed
variability of earthquake ground motions. <br>
<br>
As far as the magnitude issue you bring up, the USGS uses the
range of magnitudes that various seismologists have determined for the
1811-12 earthquakes from the intensity data. The central values of these
moment magnitude determinations range from 7.4-7.5 (Hough et al., 2000 in
JGR) to 7.8 (Bakun and Hopper, 2004 in BSSA) to 8.0-8.1 (Johnston, 1996
in Geophysical Journal). In the national maps we use a logic tree to
express this range, with a value of 7.7 given the highest weight. I used
M7.7 in the scenario in my previous email, because it is in the center of the
range of magnitudes determined for the 1811-12 earthquakes. I also gave
results for a M7.4 earthquake. <br>
<br>
In the example in my previous email, I placed the scenario
earthquake where the current seismicity trend for the New Madrid seismic zone
is located. The closest distance to downtown <st1:place u2:st="on"><st1:city u2:st="on"><st1:City
w:st="on"><st1:place w:st="on">Memphis</st1:place></st1:City> </st1:city></st1:place>is
about 60 km. <br>
<br>
-Art <br>
<br>
<br>
<br>
<br>
Art Frankel <br>
<st1:country-region u2:st="on"><st1:place u2:st="on">U.S. </st1:place></st1:country-region>Geological
Survey <br>
MS 966, Box 25046 <br>
DFC <br>
<st1:place u2:st="on"><st1:city u2:st="on">Denver , <st1:state u2:st="on">CO <st1:postalcode u2:st="on">80225
</st1:postalcode></st1:state></st1:city></st1:place><br>
phone: 303-273-8556 <br>
fax: 303-273-8600 <br>
email: afrankel@usgs.gov <br>
<br>
<br>
<o:p></o:p></span></font></p>
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<u1:p></u1:p>
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