New tsunami alert in works for NZ after Tonga eruption

1:08 pm on 28 February 2022

A new national Civil Defence tsunami alert category is being worked up following the huge impact of the Tongan volcano eruption on Northland's coastline.

Tūtūkākā marina's Sunday-morning Tongan tsunami aftermath.

Tūtūkākā marina's Sunday-morning Tongan tsunami aftermath. Photo: Tania Whyte/ Northern Advocate

No lives were lost when the tsunami hit Tūtūkākā marina after the 15 January eruption, but a woman was rescued in the dark from the sea after falling overboard into powerful swirling currents - while trying to get off her damaged boat, into her dinghy and onto terra firma.

Millions of dollars of damage ensued with boats wrecked and sunk. Meanwhile Whangaroa Harbour boaties feared they would be cast adrift after the sea's violent tsunami swirling almost forced loose their anchors.

The new notification would add specific references for boaties into tsunami notification messaging. It would take New Zealand's official tsunami advisory choices to three.

New Zealand has among the world's highest boat ownership rate, but there is currently no tsunami alerting option specifically targetting the sector.

Northland Civil Defence will be working with New Zealand's national tsunami working group to potentially develop the new option.

The Tongan tsunami hit Tūtūkākā marina hard, wrecking parts of the facility and sinking or damaging boats, causing more than $5 million in damage.

Inspecting damage was the order of the day after the Tongan tsunami hit Tūtūkākā marina

Inspecting damage was the order of the day after the Tongan tsunami hit Tūtūkākā marina Photo: Tania Whyte/ Northern Advocate

Investigating a potential new advisory has emerged in a new 15-page Northland Civil Defence post-event Tūtūkākā marina tsunami report.

Graeme MacDonald, Northland CDEM group manager, presented the report to a Whangārei District Council (WDC) community development committee meeting recently. It was written by Northland Civil Defence emergency management specialists Tegan Capp and Evania Arani.

"An option is to seek the creation of a new advisory of 'strong and unusual currents and unpredictable surges which may in some locations be enough to present a risk of injury to those on boats'," the report said.

Local Democracy Reporting has underlined the suggested additional words that could be added onto existing alerting wording.

"Neither of the present options for expected tsunami effects … are a particularly good fit for the risk to those living either permanently or on shorter overnight/holiday cruises on the water," the report said.

The report warned a residual risk of further Hunga Tonga-Hunga Ha'apai eruptions and landslides remained.

It said the effects on Whangaroa Harbour boaties were broadly covered under the 'strong and unusual currents and unpredictable surges' alert messaging, but the Tongan tsunami's risk of injury exceeded previous effects associated with such an advisory.

"People on board boats in Whangaroa Harbour in particular, … experienced violent swirling and surges to an extent that caused them to be concerned whether their anchor gear would fail under the load," the report said.

Aftermath of tidal surge at Tutukaka Marina.

Aftermath of tidal surge at Tutukaka Marina. Photo: Tania Whyte / Northern Advocate

New Zealand's two current notification categories are an advisory and the other more seriously, a warning. The advisory talks of strong and usual currents and unpredictable surges and is used when the tsunami is not forecast to spread onto land. The warning indicates a tsunami will spread onto the land and can include evacuation messaging.

The January 15 tsunami hit Tūtūkākā marina with an absence of highly visible formal public warning systems such as tsunami siren sounding, emergency mobile alerts (EMA) or Red Cross Hazard app notification.

Greg Martin, Tūtūkākā marina management trust trustee and Whangārei District Councillor, said both the sound and flashing light functions of the breakwater tsunami siren needed to be able to be individually activated to warn of pending tsunami danger. Its flashing light can be individually activated by marina management, its siren cannot.

He said the flashing light alone was not a tool that worked to wake people sleeping inside their boats in the dark.

Capp said Northland's tsunami siren network currently did not allow for sirens to be individually activated. The network was however being upgraded with individually-activated sirens, an option that could possibly be considered.

Martin said a short-term resolution was needed, ahead of any bureaucratic process that might be used that would take much longer to bring in.

There are three Tūtūkākā village tsunami sirens - on the marina breakwater, at local café Schnappa Rock and another near the village store.

The report said a pre-emptive local evacuation of Tūtūkākā's marina and surrounding buildings would have mitigated the risk to people.

This option should be worked through directly with the community - which also potentially included businesses and accommodation providers immediately surrounding the marina. It would recognise Tūtūkākā marina was more vulnerable to potentially damaging surges that other locations.

The marina community had a desire to evacuate at lower thresholds, the report said.

Any changes proposed by the marina management trust would be part of this.

Northland has six marinas and is a mecca for boaties recreationally and commercially.

Meanwhile, people fishing for flounder on foot along the tide's edge on the night as the tsunami arrived on the stormy Saturday night had to run for their lives when it hit their remote west coast fishing spot on the northern shores of Hokianga Harbour.

The Northland Civil Defence report said work was being done to establish better communication with Far North campgrounds evacuated as the Tongan tsunami arrived but outside mobile phone coverage and the existing tsunami siren network.

Cleaning up after the tsunami

More needs to be done about being able to shut the Tūtūkākā marina and surrounds during emergency tsunami cleanups, Martin said.

Hundreds of sightseers drove out from Whangārei to check out Tūtūkākā marina on Sunday, 16 January starting from early morning the day after the tsunami hit.

"We were unable to shift people out the following day. We had cranes coming in and an emergency situation," Martin said.

The villages at sea-level Marina Road (which leads into the facility) and surrounding area were crowded with people and their cars. People sat at the adjacent Schnappa Rock cafe over coffee, watching what was happening.

A single emergency services member at the eastern end of the marina carpark was inundated by pedestrians walking the length of the facility after it was closed off to vehicles. All this happened as tsunami surges continued, boat owners raced to sort sunken and damaged vessels.

Martin said the area was not cleared until the Ngunguru Volunteer Fire Brigade truck arrived, saving the day with its siren.

Sandra Boardman WDC general manager community - and a Northland CDEM group controller - said Martin's traffic management representations would be taken on board.

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