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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Ellis and Klaus,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>You both have brought up
several important issues. Let's look over some of them.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>As stated by Klaus,
"probability and uncertainty are intrinsically connected through an
underlying distribution, whether it is sampled sufficiently or not, simply by
the fact that these distributions are linked to physical processes." In
other words, in order to quantify uncertainty - estimating probability, an
underlying distribution, such as normal, log-normal, or others, has to be used
(or assumed). These can be seen through the probability estimates for the New
Madrid earthquake by Seth and Chris. The different distributions (Poisson,
Gaussian, lognormal) will give different probability estimates. However, this
is not the case in PSHA. Here are two examples.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>The following magnitudes and
weights (probability, in parentheses): 7.3 (0.15), 7.5 (0.2), 7.7 (0.5), 8.0
(0.15) were used in the 2002 national seismic hazard maps. No underlying
distribution was used or assumed in determining these probabilities (weights).
In other words, these probabilities were arbitrarily assigned. Here,
uncertainty is quantified by arbitrarily assigned probability.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Poisson distribution of
earthquake occurrences is one of the fundamental assumptions that PSHA is based
on (Cornell, 1968). And ground motion at a site is a consequence of an
earthquake. Thus, ground motion occurrences at a site should also follow
Poisson distribution. However, a lognormal distribution of ground motion
(spatial) has been used to predict ground motion occurrences (temporal)
(ergodic assumption). These are contradictory. The ergodic assumption can not
be linked to a physical process. <o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>These examples show that
PSHA is not consistent with earthquake physics and statistics. Therefore, it is
so difficult to understand the products from PSHA, and use of PSHA is
problematic for engineering design and policy consideration. The problems
related to the building codes have been discussed substantially on this
listserver. Here is an example on the problems related to the critical facilities,
nuclear facilities in particular.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>A 10.0g (ten time
gravitational acceleration) PGA design ground motion may have to be considered
for the nuclear waste repository facilities at <st1:PlaceName w:st="on">Yucca</st1:PlaceName>
<st1:PlaceType w:st="on">Mountain</st1:PlaceType> in <st1:State w:st="on"><st1:place
w:st="on">Nevada</st1:place></st1:State> based on a PSHA study. This is not a
worst case scenario from PSHA. <o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Thanks.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>Zhenming <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>___________________________________</span></font><o:p></o:p></p>
<p class=MsoNormal><st1:PersonName w:st="on"><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Zhenming Wang</span></font></st1:PersonName><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>, PhD, PE</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Head, Geologic Hazards Section</span></font><o:p></o:p></p>
<p class=MsoNormal><st1:State w:st="on"><st1:place w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>Kentucky</span></font></st1:place></st1:State><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> Geological
Survey</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>228 Mining and <st1:place w:st="on"><st1:PlaceName w:st="on">Mineral</st1:PlaceName>
<st1:PlaceName w:st="on">Resources</st1:PlaceName> <st1:PlaceType w:st="on">Building</st1:PlaceType></st1:place></span></font><o:p></o:p></p>
<p class=MsoNormal><st1:place w:st="on"><st1:PlaceType w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>University</span></font></st1:PlaceType><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> of <st1:PlaceName
w:st="on">Kentucky</st1:PlaceName></span></font></st1:place><o:p></o:p></p>
<p class=MsoNormal><st1:place w:st="on"><st1:City w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>Lexington</span></font></st1:City><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>, <st1:State
w:st="on">Kentucky</st1:State> <st1:PostalCode w:st="on">40506</st1:PostalCode></span></font></st1:place><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Phone:(859)257-5500x142</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Email: <a href="mailto:zmwang@uky.edu">zmwang@uky.edu</a></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Website: <a href="http://www.uky.edu/KGS/geologichazards">www.uky.edu/KGS/geologichazards</a></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>____________________________________</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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