ShakeAlert earthquake test reached 60% of people who expected to receive it

On Thursday, 10 years after a major earthquake and tsunami struck Japan, Oregon launched an early-warning system called ShakeAlert.

The system is already active in California, and will launch in Washington in May.

However, a test in Washington last month shows there is work to do.

On Feb. 2, Washington officials sent a ShakeAlert test message to people who had opted in to receive alerts.

A survey is the only way to know how well the test worked.

The state’s emergency management division says preliminary results show that 60% of the people who signed up expecting an alert actually got one.

That compares to 70% during similar tests in California.

>>Washington tests ShakeAlert warnings with mixed results

“There’s so many reasons why, unfortunately, they may not have received a test message, so that’s going to take a lot further analysis to look into, but that’s why we do testing,” said Maximilian Dixon, who oversees the earthquake response for the state.

State officials say alerts might not come through if someone is watching a video on their phone.

For last month’s test, it also depended on the carrier.

Eighty-seven percent of AT&T customers said they got the alert.

The alert came through for 75% of people with T-Mobile; but for Verizon, only 34% of customers received the test message.

Verizon officials say engineers are fixing a software problem related to the size of the message.

“We are in communication with Verizon and they are working on improvements,” Dixon said.

The survey found the alerts mostly arrived within 10 to 20 seconds after the state sent them.

Reaching millions of people quickly to alert them to drop, cover, and hold on is a key metric for the earthquake early-warning system to be effective.

The system detects initial seismic waves, and if there’s enough distance between the epicenter and the message recipient, sends a signal before the shaking begins.

State officials say as the launch of ShakeAlert approaches in May, it’s important that people enable emergency alerts on their phones.

Details on how to do that can be found here.