[CEUS-earthquake-hazards] The balance

[Wang, Zhenming]

Dear Laurence,

Even though blood bank is a special structure, the principles on how to minimize risk or maximize benefit are the same as for other buildings: all risks (natural and man-made) should be considered. Therefore, a 0.16g spectral acceleration at 1.0s in Memphis may not be enough if only seismic risk is considered. However, this design value may be fine if all the risks are considered in Memphis.

I am not familiar with the code changes in Tennessee. Here is the information on the residential code changes in Kentucky.

Kentucky adopted IRC-2000 in 2002 (KRC-2002) without any revision to the seismic provision. It was found that a site-specific geotechnical investigation and structural design (E zone in IRC-2000) are required in several counties in western Kentucky after the KRC-2002 took effect. This causes problems for those counties, McCracken County (where Paducah locates in) in particular. The design ground motion in the IRC-2000 was the ground motion with 2% PE in 50 years (seismic risk). What is the ground motion with 2% PE in 50 years? If you are interested in it, you can read a paper by Frankel (2004) and the comments on the paper by Wang and others (2005) and Frankel's reply (2005). As discussed in the early email, what is of safety concern in Paducah is the large earthquakes (M7-8) in the New Madrid or the ground motion generated by the earthquakes at Paducah with a 5-10 % PE in 50 years (seismic risk). The risk (the ground motion with 2% PE in 50 years) considered in the IRC-2000 is not consistent with the known risk (the ground motion with 5-10% PE in 50 years) in Paducah. This is the reason that Paducah has a higher design ground motion than that in San Francisco. After a long discussion, the ground motion with a 1,000-year return period (the ground motion with 5% PE in 50 years of the 1996 USGS national hazard maps) was selected as the design value for KRC-2002 in western Kentucky. The main reasons for selecting the 1,000-year return period USGS hazard maps (1996) are 1) the ground motion value is similar to the ground motion generated by a scenario earthquake (M7.7) in the New Madrid, 2) satisfying federal mandate (have to use the information produced by a federal agency). Currently, the 1996 USGS ground motion with 1,000-year return period is the design motion for KRC-2006.

Thanks.

Zhenming


________________________________
From: WrightLa at usa.redcross.org [mailto:WrightLa at usa.redcross.org]
Sent: Monday, January 14, 2008 12:27 PM
To: Wang, Zhenming
Cc: ceus-earthquake-hazards at geohazards.cr.usgs.gov
Subject: RE: [CEUS-earthquake-hazards] The balance

Dear Zhenming:

WRT hazard analysis and risk assessment in the St Louis area, the design requirements authors considered a number of credible hazards, both natural and manmade, and included requirements to address or mitigate all credible hazards.  Seismic risk is only one of a number of risks that were considered.  Most of the design response to these hazards were not dictated by building codes.

A blood bank, in some ways, is a unique type of structure;  a single blood  processing facility may serve hundreds of health care facilities.  If the blood bank is not able to deliver blood, any medical care that requires blood or blood products  cannot be delivered.  In the context of the aftermath of a large earthquake in the CUS, if a blood bank were not able to deliver blood products, that would mean that many thousands of trauma patients would not receive life-sustaining medical care.

As you correctly point out, risk analysis is a complex subject, and there is more to it than just dollars and cents.  It is perhaps as much art as science. We are, however, as an organization that depends on our donors, compelled to ensure that we get the most bang for our donated dollar.  We are also an organization dedicated to preventing human suffering, and I am certain that with the knowledge at hand that we have done the best job we can to balance these organizational imperatives.  But as stated above, a blood bank is really a peripheral issue, considering the relatively few blood banks in the US,  when compared to the thousands of structures and  millions of people who could be affected by an earthquake in the CUS.

I regret that this side bar appears to be on the way to derailing an interesting and informative discussion on risk perception and public policy;  could I hear some more about the specifics of the code changes in Tennessee?.


Laurence M. Wright

Senior Project Engineer

Manufacturing Engineering

202-303-4457 (o)

202-549-5843 (c)

-----Original Message-----
From: ceus-earthquake-hazards-bounces at geohazards.cr.usgs.gov [mailto:ceus-earthquake-hazards-bounces at geohazards.cr.usgs.gov] On Behalf Of Wang, Zhenming
Sent: Monday, January 14, 2008 9:19 AM
To: Wright, Laurence
Cc: ceus-earthquake-hazards at geohazards.cr.usgs.gov
Subject: Re: [CEUS-earthquake-hazards] The balance

[Wright, Laurence] <snip>

It may not be wise to have higher seismic design requirements for the new Red Cross blood center in the St Louis area (considering seismic risk only). Other risks should also be considered.

Thanks.

Zhenming


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