Are You Living on a Fault Line?

The California Geological Survey puts its earthquake zone maps online.

It's hardly news that we're living in an earthquake zone, but now you can see exactly how close to your home the existing or suspected fault lines lie, via your computer.

The California Geological Survey has put its earthquake zone maps online and you can view them by going to the Geological Survey's earthquake zone mapping page and entering your address. When the map comes up, click on the quadrangle in which your address is located. There is a quadrangle for Seal Beach and one for the Rossmoor-Los Alamitos area.

A box will pop up. Inside the box, at the bottom, are links to downloads of the survey maps. Download one of those maps and examine it for the dark solid or dotted lines -- you may need to zoom in to get a good look. (See the example at right.) According to the Associated Press, the state's 547 maps were previously available only on paper or CDs.

According to the map, the Newport-Inglewood fault runs from Belmont Shore into Seal Beach near the Marina Bridge and heads under the Hill neighborhood, the Seal Beach Naval Weapons Station and the National Wildlife Refuge before heading south into Sunset Beach.

According to the U.S. Geological Survey, there have been two earthquakes of late that Seal Beach and Rossmoor residents may have felt, including a 3.8 quake epicentered just off the coast in November and a smaller 2.0 quake epicentered in Long Beach at the end of December.

In 1933, a 6.4 magnitude earthquake in Long Beach caused significant damage to Seal Beach, destroying portions of the old Zoeter School.

According to Seal Beach’s Emergency Operations Plan, the major threat from an earthquake is a process called liquefaction in which major shaking blends soil and water, destabilizing structures above.

The other earthquake concern for the area is the tsunami resulting from a quake. Any tsunami affecting Seal Beach would likely be caused by an earthquake very far away, such as the Alaskan 8.4 magnitude quake in 1964 that caused 5-foot tidal surges in Seal Beach. Today, the city has a reverse 911 system in place in to issue tsunami warnings.

 Paige Austin contributed  to this report.


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