HILO, Hawai'i — An electrical failure and a failed generator produced some communication problems on the Big Island after the magnitude 5.0 earthquake on Thanksgiving Day, but the temblor also gave state Civil Defense officials a chance to try out a new procedure for updating the public after a quake.

Big Island Civil Defense officials use local radio stations as their primary method of communicating with the public in emergencies, and Big Island Mayor Harry Kim was in contact with stations to offer a report less than 10 minutes after the 9:20 a.m. Thanksgiving earthquake.

However, most radio stations serving Kona went off the air after the Thanksgiving earthquake because electricity was cut from Pu'uanahulu to Kalaoa, severing power to radio transmitters in Kaloko Mauka, said Troy Kindred, Big Island Civil Defense administrator.

Kindred said there are two backup generators to serve the Kaloko transmitters, but one was out of service while it underwent maintenance, and the second failed to function when the power went out.

That meant that until power was restored about 90 minutes later, Kona listeners were unable to catch signals from stations belonging to Pacific Radio Group and New West Broadcasting, although a Skynet Hawai'i AM station did remain on the air, he said.

Kona listeners who scanned for a signal likely could also have picked up broadcasts from Maui to obtain updates on the earthquake, he said.

Chris Leonard, general manager of New West Broadcasting, said his station has about $30,000 worth of backup generators on order to power his system, and the new equipment is to be installed before the end of the year.

Although the quake did little damage, state Civil Defense vice director Ed Teixeira opted to use the Emergency Alert System to reassure the public that the quake did not generate a tsunami.

The Emergency Alert System uses voice and text messages that can be picked up on any radio or TV station, and are often used by the National Weather Service to alert the public about flooding or other weather hazards.

Thursday marked the first time the system has been used to announce there was no tsunami risk from an earthquake, said Ray Lovell, public relations officer for state Civil Defense.

The plan to do so grew out of the magnitude 6.7 and 6.0 earthquakes on Oct. 15, when Civil Defense officials knew there was no tsunami but did not make a public announcement to that effect until almost three hours after the earthquake. That decision was criticized by some residents who wanted more information and wanted it earlier.

There were some glitches on Thursday, however. Lovell said Civil Defense officials had not yet formalized procedures on issuing a post-earthquake tsunami all-clear message on the Emergency Alert System, and the message was not actually sent out until 9:57 a.m.

"In the future, what we hope to do is get a message out to the public within five to 10 minutes," Lovell said. "Knowing that large portions of the state may feel it, it's important to get a message out quickly that no tsunami has been generated."

Another problem was that some specialized National Weather Service coding was included in the text message, and that confused some viewers, Lovell said. Civil defense officials plan to review the procedures for producing those messages, he said.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.