what is seismic zonning?

Asked by Emad, Cairo, GA Mon Oct 1, 2007

emad kamal

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Ted Stephanos, , San Jose, CA
Tue Oct 16, 2007
I think the previous answers were accurate but I also wanted to touch on the fact that seismic zoning is typically related to soils and how they behave during seismic activity, or simply put, earthquakes. The softer the soil, the more susceptible the area would be to seismic shaking in an earthquake prone region. The potential for liquefaction would be greater in these areas. In general, you need sandy soil, near-surface groundwater, and an earthquake for liquefaction to occur.

In California, the state has released Earthquake Fault Zone maps (beginning in the early 1970's) which outline where active faults exist in the state. Over the past decade, the state has also released Seismic Hazard Maps which outline liquefaction and landslide zones. Only portions of the state (mainly Los Angeles, Orange, Ventura, San Francisco, Oakland and San Jose) have been mapped to date, but new maps are released each year.

The map Sylvia is referring to are Uniform Building Code map which give a number 1-4 to areas in the United States with 4 being the most prone and 1 being the least. All of California is in a 3 & 4 zone, for example.
Web Reference:  http://www.bluenhd.com/
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Sylvia Barry,…, Agent, Marin, CA
Mon Oct 1, 2007
Hi Emad:

The seismic zoning identifies the areas where there are (or not) earthquake potentials. The zoning also distinguish the degrees of earthquake likelihood. Knowing whether a property is in a certain Seismic zoning is very important in California as we have a few major faults here and are quite prone to earthquake.

I see you are from Arkansas, so I found this seismic zones map for you.


This is kind of interesting information me. My sister lives in Arkansas and I have never suspected that Arkansas has earthquake zones there, and I looked up another article, it talks about the New Madrid Fault Line which is centered in northeast Arkansas - which you will see is where some of the zone 3s (with Zone 4 having the greatest seismic potential) are.


Hope this helps.

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Ute Ferdig, Agent, Newcastle, CA
Mon Oct 1, 2007
Hi Emad. Welcome to Trulia voices. Sesmic zoning refers to earthquake zones. There are earthquake zones that are rated and other zones that are not officially rated perhaps because of insufficient data. I see you are in Egypt and I don't know anything about earthquake activity you that country. I only know that there are lots of areas in CA that are known as earthquake zones. When people buy real estate here, the seller has to provide the buyer with a Natural Hazards Report. Since most sellers are not qualified to provide the detail that is required by law, there are companies that specialize in compiling the information and sellers order the reports. A part of the Natural Hazards Report addresses whether the property is in an earthquake zone and if so what the rating is (if available). This is standard disclosure in CA. It would be interesting to know what the situation is in Egypt. Please come back to Trulia and share your experience with us.
Web Reference:  http://www.go2kw.com
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