Nationwide emergency alert test at 2 p.m.

WASHINGTON -- This is only a test. Seriously.

That's what the Federal Emergency Management Agency wants the public to know about the first nationwide test of the emergency alert system Wednesday at 2 p.m.

The decades-old warning system is often tested locally, but it has never been tested on every radio and TV station in the country at the same time, according to FEMA.

The audible message will indicate that it's only a test, but the visual message may not, according to an email sent out by the Notify NYC alert system.

FEMA is trying to get the word out about the test to avoid unnecessary alarm like, say, the panic caused by Orson Welles' 1938 radio broadcast of a fictional Martian invasion in New Jersey.

Officials also want to prevent the test from tying up 911 phone lines.

"We have alerted our 911 call centers about the possibility for increased call volume during the Nov. 9 test," Alisa Simmons, a spokeswoman for the 911 network in Tarrant County, Texas, said in a statement appealing to the public not to call to inquire about the exercise.

Some 30,000 radio and TV operations will participate in the 30-second test, which will sound and look like the familiar local tests.

Federal officials considered a three-minute test but decided on 30 seconds "to reduce any potential disruptions to the American people, while still maintaining our ability to test the system's nationwide capabilities," said FEMA spokeswoman Rachel Racusen.

The alert system can be activated by the president to inform the public in times of emergency, The Associated Press reported. "It's just a test," presidential spokesman Jay Carney said.

The test has generated chatter on FEMA's blog, with one person commenting, "How about cellphones? Everybody has one. Your system is outdated."

The Federal Communications Commission has moved to extend the emergency alert system to cellphones, beginning in the New York area by the end of the year and reaching the rest of the country by next spring.