U.S. Siesmic Zones

[7897]

Has anyone heard of a siesmic zone 8 in the United States? a co-worker insists there is a zone 8 but I don't think so. If one does exist, can someone provide me with some information?

Thank you.

 

[jproj]

7897:

SEISMIC ZONE 8!?? UBC only goes to zone 4, which is the highest I've ever heard of.

jproj

 

[amokhta]

There are only seismic zones 1 through 4 in UBC. This is up to UBC-97. However, the new 2000 IBC seismic design provisions does not use seismic zones to establish design earthquake loads any more. Instead IBC uses a parameter called Seismic Design Category for imposing design and detailing requirements. Seismic Design Category of a structure is a function of three parameters: probable site ground motion, the type of soil at the stucture site, and the building occupancy category.

 

[whymrg]

Ask if they mean Richter Magnitude 8 or Mercalli Intensity 8?
They might.

 

[JAE]

Just being picky, amokhta, but actually the seismic zones in the US vary from 0 to 4, not 1 to 4.

 

[amokhta]

JAE: Thank You. You are right. It was a typo on my side.

 

[Rich2001]

Here are two links that may be helpful:

http://www.geophys.washington.edu/CREW/Graphics/HAZMAPS/maps_ubc.html

http://geohazards.cr.usgs.gov/eq/

has the
DRAFT USGS NATIONAL SEISMIC HAZARD MAPS, JANUARY 2002

 

[Dinosaur]

In the AASHTO Standard Specifications for the Design of Highway Bridges, Division 1A - Seismic Design, they divide the U.S. into for Categories; A thru D. Almost everything East of Nevada is Category A.

It sounds like your friend is mixed up on his facts.

 

[Clydelang]

Can Anyone tell me what Design Category Kitsap County State of Washington, Bremerton Area is? I know that according to the 2003 IBC it is either D1 or D2

 

[JStephen]

Ask him what code he's referring to and then look it up. Seismic zones exist only as defined by a building code or other standard; they aren't stripes painted on the ground. You could always write "Bubba's Building Code" with zones from 1 to 99 or whatever you wanted.