Don’t wait for sirens be­fore act­ing

Coastal News - - News - By ALI­SON SMITH news@coastal­news.co.nz

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.

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