What is a Seismic Zone?
A seismic zone could be one of three things: A region on a map in which a common level of seismic design is required. This concept is becoming obsolete. An area of seismicity probably sharing a common cause. Example: “The New Madrid Seismic Zone.” A region on a map for which a common areal rate of seismicity is assumed for the purpose of calculating probabilistic ground motions.
A seismic zone is a region in which the rate of seismic activity remains fairly consistent. This may mean that seismic activity is incredibly rare, or that it is extremely common. Some people often use the term “seismic zone” to talk about an area with an increased risk of seismic activity, while others prefer to talk about “seismic hazard zones” when discussing areas where seismic activity is more frequent. Many nations have government agencies concerned with seismic activity. These agencies use the data they collect about seismic activity to divide the nation into various seismic zones. A number of different zoning systems are used, from numerical zones to colored zones, with each number or color representing a different level of seismic activity. In the United States, for example, the seismic zones are divided between one and five, with zone five being the most at risk of seismic activity. Most high-activity seismic zones are located along what are known as fault zones, regions of t
