[CEUS-earthquake-hazards] alternative hazard maps

[Eugene S Schweig]

Zhenming,

While your question is simple, it is also misleading.  If we could count 
on M 7.7 earthquakes happenning every 500 years, and we could count on the 
ground motions always be the same at each of these locations for a New 
Madrid event, and if a repeat of 1811-1812 were the only thing that could 
cause that level of ground motions at each location, our leaders could go 
to bed happy that it would be at lest 200 hundred years before they had to 
start building safe buildings.  Sadly, none of this is true.  We have 
little information on the regularity of earthquake timing.  We know there 
can be significant variation in the ground motions generated by the same 
size earthquake from even to event because of a number of factors.  We 
also know that other earthquakes besides a repeat of the 1811-1812 
earthquakes may contribute to the possibility of large ground motions, 
particularly with increasing distance from New Madrid.  So while the 
question is simple, the answer is not, which I am sure you already know.

Buddy
Fading into the Central U.S.Seismic Sunset
__________________________________________________________________
Eugene Schweig
Chief Scientist
Earth Surface Processes Team
U.S. Geological Survey

Denver Office:
MS980 Federal Center                                      (303) 236-5344
Denver, CO 80225-0046                         Fax: (303) 236-5690

Memphis office: 
3876 Central Ave., Ste. 2                                 (901) 678-4974
MEMPHIS, TN  38152-3050                     Fax: (901) 678-4897
___________________________________________________________________





"Wang, Zhenming" <zmwang at email.uky.edu> 
Sent by: ceus-earthquake-hazards-bounces at geohazards.usgs.gov
02/07/08 07:24 AM

To
Arthur D Frankel <afrankel at usgs.gov>, Seth Stein 
<seth at earth.northwestern.edu>
cc
"ceus-earthquake-hazards at geohazards.usgs.gov" 
<ceus-earthquake-hazards at geohazards.usgs.gov>
Subject
Re: [CEUS-earthquake-hazards] alternative hazard maps





 
Here is a simple question for every one: If an M7.7 earthquake occurs 
every 500 years in the New Madrid seismic zone, how often will the ground 
motion generated by that earthquake be observed in Memphis, St. Louis, or 
Paducah?
 
Thanks.
 
Zhenming 
 
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