Don’t wait for sirens before acting
Earthquakes generated from the most likely source of a devastating tsunami on the Coromandel may not be felt on land and would leave just minutes to get to safety, according to new research.
Despite a nationwide campaign of Long, Strong, Get Gone, Emergency Management authorities are telling residents to sign up for emergency alerts on their mobile phones and practise getting themselves to higher ground because the natural warning signs of a long or strong earthquake may be absent.
“Earthquakes generated in the Kermadec Trench may not be felt strongly and could generate a tsunami that may arrive in as little as an hour,” says Garry Towler, TCDC Emergency Management manager.
“This means the public may be asked to evacuate due to an imminent tsunami risk from an earthquake that may not have been widely felt. In such scenarios, warnings will be issued as soon as a tsunami threat is identified to ensure that the public have the earliest possible notice to self-evacuate,” he says.
An official Shake Out Day was held last Thursday — the day around the world to remind people of the right action to take during an earthquake or tsunami evacuation.
The message has always been that if people experience the natural warning signs of a local source tsunami, such as if an earthquake is long or strong, they should “get gone”.
“Anyone near the coast who feels the earthquake of more than one minute or strong — making it hard to stand up — or sees or hears unusual ocean behaviour must evacuate immediately,” a media release states.
The Kermadec Trench poses a risk to most of northern New Zealand, but especially to the Coromandel, Great Barrier and parts of Northland, according to tsunami modelling by scientists.
A report, Tsunami hazard posed to New Zealand by earthquakes on the Kermadec and southern New Hebrides subduction margins, says travel times between the Kermadec Trench and these high-risk locations are in the 45 minute to two hour range, which permits some form of warning to be issued, though current technology will leave a great deal of uncertainty about the source during this timeframe. ■
Mr Towler says residents should not rely on tsunami sirens.
“Local source tsunami — that is, generated close to the New Zealand coast — are different to regional or distant tsunami, which originate further away from New Zealand and allow more time for thorough scientific assessments and evacuations. In a local source tsunami, there may not be time for an official warning before the first waves hit.”
He says warnings and evacuation maps will be issued via Emergency Mobile Alerts, news media, the Civil Defence website, @Nzcivildefence Twitter and Nzcivildefence Facebook.
“Just because you didn’t feel shaking doesn’t rule out the possibility of a local source tsunami happening. This is why it’s so important to know what to do and where to go, so when a warning is issued, you’re all set to go.”
He adds: “The Indonesian tsunami is a tragic reminder of how swift and destructive tsunami can be. New Zealand has extensive arrangements for monitoring, detecting and issuing warnings about tsunami — but just as important is the public knowing what to do.”
The council wants people to practise evacuations by walking or cycling. They should know where to go, whether they may be at home, at work or out.