[CEUS-earthquake-hazards] Report on estimating maximum magnitude in the Central and Eastern US.

[Joe Tomasello]

It seems to me that risk of collapse is primarily related to two basic
functions, the level of the hazard, and the length of time exposed to the
hazard, e.g. high hazard *low exposure = little risk; conversely low hazard
*high exposure = little risk (the inverse would also be true to produce high
risk).  The problem with the hazard maps in the building codes is that they
don't evenly account for the relative exposure to earthquake hazards across
the U.S.  Only after evaluating risk can I determine an economically sound
mitigation effort that best fits available resources.

Joseph Tomasello, PE
5880 Ridge Bend Rd.
Memphis, TN 38120
 
Phone:
(901) 761-2016 office
(901) 821-4968 direct
(901) 412-8217 mobile

-----Original Message-----
From: ceus-earthquake-hazards-bounces at geohazards.usgs.gov
[mailto:ceus-earthquake-hazards-bounces at geohazards.usgs.gov] On Behalf Of
Krinitzsky, Ellis L ERDC-GSL-MS Emeritus
Sent: Thursday, May 07, 2009 9:01 AM
To: Central and Eastern U.S. Earthquake Hazards Listserve
Cc: Wang, Zhenming
Subject: Re: [CEUS-earthquake-hazards] Report on estimating maximum
magnitude in the Central and Eastern US.

Everything depends on the criticality of the structure. If the structure is
critical (the consequences of failure are intolerable) then one must design
for the maximum earthquake regardless of temporality. Otherwise, it is
proper
to design on a cost-risk basis.

Nobody can say that a 1,000-year earthquake or a 10,000-year, both based on
150-year record, will not happen tomorrow. The 10,000-year earthquake,
assuming the time estimate has any meaning, could just as well be more
likely
to happen.

Ellis Krinitzsky
Corps of Engineers, ERDC, Vicksburg

-----Original Message-----
From: ceus-earthquake-hazards-bounces at geohazards.usgs.gov
[mailto:ceus-earthquake-hazards-bounces at geohazards.usgs.gov] On Behalf Of
Wang, Zhenming
Sent: Thursday, May 07, 2009 8:11 AM
To: Central and Eastern U.S. Earthquake Hazards Listserve
Subject: Re: [CEUS-earthquake-hazards] Report on estimating maximum
magnitude
in the Central and Eastern US.

The maximum magnitude earthquake is one of the key parameters that affect
seismic hazard estimates the most in the central and eastern United States.
However, the occurrence frequency of the maximum magnitude earthquake is
also
important for seismic hazard assessment. For example, an M7.5 earthquake
with
a recurrence interval of 1,000 years will have a significantly different
implication for engineering design of a facility than the same earthquake
with a recurrence interval of 10,000 years. Therefore, the temporal
characteristics of the maximum magnitude earthquake must also be considered
in the determination of the magnitude.



Zhenming



--------------------------------------------------------------

Zhenming Wang, PhD, PE

Head, Geologic Hazards Section

Kentucky Geological Survey

Adjunct Professor

Department of Earth and Environmental Sciences

228 Mining and Mineral Resources Building

University of Kentucky

Lexington, KY 40506

Phone: 859-257-5500ext142

email: zmwang at uky.edu

www.uky.edu/KGS/geologichazards/

www.uky.edu/AS/Geology/faculty/wang.html

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