NEMA identifies mobile phone alert problems during tsunami warning

The National Emergency Management Agency has revealed what caused people to get multiple alerts to their phones - or no alerts at all - during the tsunami scare caused by the 8.8 earthquake off Russia last month.

The answer boils down to a combination of individual device settings, cell tower coverage and where the tsunami alert was sent - for example, those living far away from coastal areas were not included in the alerts. There were no failures with the system itself, NEMA said.

"We know explanations are little consolation for those who were awoken by alerts in the middle of the night," said NEMA director Civil Defence Emergency Management John Price in a review the agency released on Wednesday.

"We are very sorry that this happened, and we're looking at ways to address this in future. However, we make no apologies for getting the message out to keep people safe."

• How does the Emergency Management Alert system work, anyway? Here's our full explainer.

"NEMA only issued two alerts - at 4.13pm on 30 July and 6.30am on 31 July - but some people received multiple alerts during the night. We've discovered this is likely related to overnight software updates and device settings.

"As for those who didn't receive alerts, tsunami alerts are only sent to coastal areas, so if you were inland then we didn't send you the message because you were not at risk."

Why some got multiple alerts

Some people reported receiving up to 50 mobile alerts.

Marlborough resident Terry Costello told RNZ he got the first alert on that Wednesday afternoon, followed by many more.

"By the time I went to bed at 10pm, they were still going on and there'd been 32 of them by then. And I turned my phone off at 10pm and went to bed. And I turned it on again at 7am this morning and since then I've had another 16. So that's 48 altogether I've had."

NEMA laid out several reasons why this might have happened:

• When your phone does an automatic software update overnight it reboots. If you turn your phone off and on again during an alert broadcast, you will get the alert again. So when your phone reboots after an update, you will get the alert a second time.
• During the early morning hours, some devices refresh their network connections. This process may have cleared cached data, prompting your phone to give you the alert again. While your device should recognise that it has already received and displayed the alert, it appears that some devices are more conservative and elect to redisplay.
• If you have multiple active Sims / eSims, you will get an alert for each Sim.
• If your phone moved between 3G and 4G networks during the alert broadcast, you will get the alert again each time your phone connects to the new network. This can happen if you're travelling into a poor coverage area, or if your phone drops in and out of networks.
• Some phones have an optional alert reminder feature turned on. This can cause your phone to alarm repeatedly during the alert broadcast. If your phone does have this feature, you should be able to find it in your phone settings and turn it off.

"As we don't have any control over how individual devices behave, we can't completely stop these issues from happening again - but we are looking at ways we can reduce their impact," Price said.

Alert delays, or not getting it at all

Alerts use cell broadcast technology known as geotargeting to send alerts through cell towers in a selected area which can be the entire country or down to a small section of a city.

"We identify the cell towers from all three telecommunications companies in the hazard area, draw a shape around them, and send the message to the area inside that shape," Price said.

Some reported not getting the alerts at the same time as others. People might have received the 4.13pm or 6.30am alerts later because they entered the broadcast area.

"We continued to transmit these alert broadcasts for several hours. This was so people entering the area later still got them. You might have got an alert when commuting home at 5.30pm, or into work at 8am.

"The most likely answer is that you were outside the coastal areas we sent the alert to. But then you entered the broadcast zone at a later time, triggering the alert on your phone."

If a person's phone was off or in flight mode they would receive the alert once it was turned back on.

Some may not have gotten an alert at all during the tsunami scare, but that could be because it was aimed only at coastal regions - which admittedly covers most of the country, but not all of it, Price said.

"Do you live in Hamilton? Palmerston North? Geraldine? Or perhaps an inland suburb of a coastal city? Then don't worry - we never sent it to you."

In some households, there were reports that one person got the alert but another person did not. This is typically due to being on the border of the geotargeted broadcast area, Price said.

"The geotargeted areas aren't a clean border. It depends on where the cell towers are and how far they transmit.

"If some people in your household get the alert and others don't, you're probably right on the border and those who didn't get the alert may have a different network provider or are connected to a different cell tower than those who did."

NEMA also has a section on their website where people can troubleshoot issues with alerts.

Why was a second alert sent at 6.30 in the morning?

The second tsunami alert that came at 6.30am on 31 July also drew a lot of criticism at the time on social media, with one person on Reddit calling it "an anxiety inducing alarm clock".

However, NEMA said it has a statutory responsibility to warn of the ongoing risks as people began their day.

NEMA chief executive Dave Gawn defended the early hour, writing in an editorial that "this is where the tough decision making comes in".

"We knew we would wake some people up. We knew there'd be criticism. But we also knew the tsunami activity - while not spectacular or scary to witness - posed a grave risk to every one of those people.

"We're hard-wired in our profession to plan for the worst case scenario. Imagine if a mother or father - having not received any alerts since the previous afternoon - assumed the threat had passed. Later that morning, they take their toddler to the beach for a paddle, only to helplessly watch their child get swept away by a fierce current."

People cannot opt out of the mobile alerts, and the only way to avoid them is turning off your phone entirely or putting it in airplane mode.

Price said that despite the kinks in last month's tsunami alert, NEMA had confidence in the system overall.

"The good news is that there is no problem with the systems we use to send the messages," he said. "The alerts were effective in reaching the targeted coastal areas and getting the message out to stay away of the water while dangerous tsunami activity was happening.

"We sent alerts to over three million mobile devices around the country, and when you consider the sheer variety of makes, models, and software, it's inevitable some variations will emerge at the receiver end.

"After every emergency, we debrief to identify what went well and what needs to improve. We're working through this now to ensure we're doing the best we can at keeping people safe from tsunami and other threats."

NEMA said they are still analysing the tsunami event and have not yet identified any potential changes in the system they may make.

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