Text messages, emails and other electronic tools played key roles as Hawaii’s civil defense agencies tried to get the word out quickly and accurately about last month’s tsunami here generated by the earthquake off Japan, officials said.

Officials also said they believe Nixle and similar forms of messaging systems, as well as social media such as Facebook and Twitter, will play an increasingly vital role in notifying the public about disasters, emergencies and other events.

The Honolulu Police Department quietly began using Nixle last month to send out traffic advisories. Anyone from the public signed up for HPD Nixle messages would have found out, for example, in an email or smartphone text message Thursday afternoon that part of Wai­alua’s Kau­kona­hua Road was shut down for several hours because of a fatal head-on crash.

John Cummings III, public information officer for the city Department of Emergency Services, said he has no way of knowing how many of the agency’s estimated 3,200 Nixle users first learned of the earthquake through a text message or email, but noted that he’s heard from many of them.

The department sent a Nixle alert to subscribers at 8:13 p.m. Hawaii time on March 10, 15 minutes after the Pacific Tsunami Warning Center first issued a tsunami watch for Hawaii and 26 minutes after the initial earthquake.

"What Nixle provides is a means for our department to quickly message residents who register to receive our alerts and information bulletins," Cummings said. And the messages didn’t stop with the initial warning: The department issued more than a dozen other messages throughout the event, ending with Mayor Peter Carlisle’s all-clear declaration at 8:12 a.m. March 11.

Hawaii County Civil Defense does not use Nixle, but a similar service provided by Talisman LBS that, like Nixle, has been providing basic text-messaging service to government agencies for free. Quince Mento, Hawaii County Civil Defense administrator, said his agency has been using the service for about two years and has about 4,000 subscribers.

"We’re very happy with them," Mento said.

Citywatch Notification Systems, a separate company, provides email notification and what’s known as a "reverse 911" alert system in which subscribers get a recorded voice message to their telephones. Unlike text messages and emails, reverse 911 calls can be sent to traditional land-line telephones.

Citywatch has provided its services free to Hawaii County for the last three years but will start charging about $40,000 annually starting in July, Mento said. Talisman is also expected to start charging soon — 6 cents per text, Mento said.

Cummings said Nixle has assured the City and County of Hono­lulu that it is a "test city" that will be able to continue using its services free.

Kauai County began its Connect CTY service to notify its residents of disasters and other emergencies in May 2009, said county spokes­woman Mary Dau­bert. For about $52,000 annually, Blackboard Connect Inc. provides the county a database of 23,472 telephone numbers to which it can send out text messages and emails, as well as voicemails to land and cell lines, even receiving devices for the hearing impaired, she said.

"On the day of the recent tsunami, it afforded us the opportunity to alert those in the system early enough so that they could begin to immediately plan for evacuation (if that was required), and to urge them to monitor the event through the media," Dau­bert said. "So far, we have only received positive feedback."

The service has also been used to alert Garden Isle residents of flash flood warnings, localized water outages and other events, she said.

CivicPlus, another private provider, gives Maui County residents a wide range of services that go far beyond disasters and emergency alerts. People can sign up to be notified about job openings, contract bid notifications and government meetings.

How much the county pays for the service, or how long it’s been in use, was not available.

The Hawaii County Police Department has been using Nixle since September 2009 and is among its most active users. Chris Loos, department spokes­woman, said the department uses Nixle to alert Big Island residents not just of road closures, but also Crime­­Stop­pers bulletins and notices of missing people.

Honolulu dispatch personnel recently completed training on how to send traffic advisories through Nixle and began sending out notices last month on water main breaks, critical and fatal traffic collisions, fallen trees and other events that affect traffic.

HPD spokeswoman Michelle Yu said there are no plans at this time to use Nixle to alert people about Crime­Stop­pers, searches for suspects or other issues.

"HPD is aware that people are increasingly receiving information from nontraditional media, and the department is considering various ways to communicate with the public," Yu said.

Honolulu’s Emergency Services Department first began using Nixle in August. Since last month’s tsunami, the agency’s subscribers have increased to more than 3,600, a jump of more than 10 percent, Cummings said.

Agencies are using other social media tools to reach the public during disasters. State civil defense, Maui County and various Hono­lulu agencies send out messages on Twitter, while Kauai and Maui counties have Facebook pages.

Emergency response officials applaud the social media phenomenon but warn it’s not a complete replacement for time-honored ways of keeping in touch with government agencies during a disaster.

"I think the more venues you have to get the information out, the better off you are," Mento said. "In the end it all boils down to the coconut wireless. I don’t think we’ll be able to reach every single person, but the more people we can reach out there, they can send a message out to their family, friends and loved ones."

There are also some limitations with relying on cellphones. AT&T officials, in response to complaints of slow or spotty service during the tsunami, acknowledged that its system was overburdened when its call volume reached five to six times more than normal during the crisis.

"It goes to show you, you can’t rely on one thing," Mento said.