Siesmic Zone 8

[7897]

Can anyone tell me if a siesmic zone 8 exists in the United States? A co-worker insists that one exists but I don't think so. If one exists, can someone point me in the direction to obtain some information?

Thank you

 

[Qshake]

Absolutely NOT!

Presently there are Zones 1-4 with 4 being the zone of highest probable ground acceleration.

In other codes such as the AASHTO code for bridges, the zones are denoted as Seimsic Performance Categories (SPC) and are A, B, C, and D. In this case, D is the category of highest probable ground acceleration.

 

[JAE]

As per the other thread - zones 0 to 4.

 

[Qshake]

I'm sorry, what do we have to do in zone 0? Just kidding! I stand corrected. Thank you JAE.

 

[JAE]

I know I was a little ridiculous....Zone 0 is really no seismic zone at all....just a zone without seismic.

 

We have an on going debate in our office about a Zone V, and I fully accept the explaination that there is currently only Zones 1-4 and A-D, but I have recieved a request to quote a project designed to seismic Zone 5 (this is in South America). Can you tell me were to find any hard documentation on the Zones. I've looked all over the web but with no luck. Please help.

 

[JAE]

The "zones" that Qshake refers to are seismic design zones developed in the U.S. through the Uniform Building Code. If you have a requirement for a zone in SA then I would try to find the source of this zone requirement and find out what governing code is referenced.

If your source tells you that its just like in the U.s., then they are mistaken as there is no zone 5 or equivalent in the UBC.

It must be an SA code of some sort - or they are simply mistaken.

 

Thank you, I think you are absolutely correct. I have been researching this this morning, and have found out that the Zones are determined by a risk factor that takes into account magnitude, duration, and attenuation. The most important factor seems to be the Peak Ground Acceleration as it relates to the acceleration of gravity. The example given was as follows: "If you live in seismic zone 4, you have a one in ten chance that an earthquake with an active peak acceleration level of 0.04g (4/10 the acceleration of gravity) will occur within the next fifty years. Likewise, if you live in zone 1, you have a one in ten chance that an earthquake with an active peak acceleration level of 0.1g (1/10 the acceleration of gravity) will occur within the next fifty years". There is a very good map that shows some zone 5 areas in Central America. Check it out:
seismo.ethz.ch/gshap/notham/shednh_8col.gif

 

Sorry, I left out a letter in the url. Try this one: seismo.ethz.ch/gshap/northam/shednh_8col.gif