In the exercise, the earthquake generated tsunami waves that swept along the coastline through Hicks Bay/Wharekahika, Ruatōrea, Tikitiki and Muriwai. These were the worst hit with waves up to 15m high.
The city was completely inundated with fast-moving water and debris, with flooding right back to the Dalrymple and Ormond Road area.
Around the table were representatives from iwi, health, Fire and Emergency NZ, police, the New Zealand Defence Force, Ministry for Primary Industries, Gisborne District Council and more, all covering the functions of an actual emergency response — intelligence, operations, welfare, and public information.
TEMO general manager and group controller Ben Green said there was
much to be learned by all in exercises like this.
“This provides a realistic environment
to test and develop processes, procedures and exposure to people working in an emergency centre environment,” Mr Green said.
He said given the adverse weather the region had experienced in the past 18 months, those who were part of the responses were well versed in what needed to be done.
“The events we have been dealing with of late have been weather-related, so it was interesting to do an exercise around a big earthquake and subsequent tsunami.
“The Hikurangi Subduction Zone represents Aotearoa’s greatest seismic threat and the time between a rupture and tsunami arrival is minutes.
“That means we need solid plans in place to respond effectively to something that would create significant devastation.”
Mr Green says there is valid concern about the subduction zone, given there is a 26 percent chance of a significant event in the Hikurangi Fault occurring within the next 50 years.
“People are always at the centre of any emergency response which underlines the importance of these exercises.
“Our welfare arm provides for the needs of affected people, and we also have support to prevent escalation of situations and minimise the consequences of the emergency on whānau and communities.”
Two New Zealand Defence Force (NZDF) personnel attending Exercise Horowhatu explained how the NZDF was prepared to support emergency services.
“They also ensured all agencies understood how to request NZDF assistance in times of emergency,” a NZDF spokesperson said.
“The exercise also showed that the NZDF is integrated with all layers of government to provide disaster relief at both regional and national levels.
“Any response will always be influenced by both the scale of the event and the specific needs of the local authorities. However, the NZDF always maintains an effective response to disaster events in both New Zealand and the wider region.”
Exercise Horowhatu was the third such exercise run in Tairāwhiti by TEMO, with each feeding into the catastrophic event plan which is set to be completed in 2024 which will coincide with the development of the national plan.
Tairāwhiti will take part in a 2024 nationwide National Emergency Management Agency exercise which feeds into the development of the national Hikurangi plan for Aotearoa New Zealand.
Over the past five years, a large team of national and international scientists have been studying the Hikurangi plate boundary to find out what risk it poses to New Zealand. The Hikurangi plate boundary, located off the East Coast of the North Island, is where the Pacific tectonic plate subducts (or dives underneath) the Australian tectonic plate.
The Hikurangi subduction zone runs the length of the North Island’s East Coast, passing as close as 40km offshore from Gisborne.
The scenario being used by emergency planners follows a rupture off the Wairarapa coast and is intended for testing the plan during an emergency management exercise.
It is not a prediction of future impacts.
The scenario envisages that just after 9am on a winter school day, a magnitude 8.9 earthquake occurs on the Hikurangi plate boundary, sparking “intense” shaking along the whole east coast of the North Island between Wellington and East Cape.
The worst affected regions are Wellington and the East Cape, where the landslides are comparable to those in Marlborough after the 2016 Kaikoura earthquake.
In Gisborne buildings have collapsed, due to shaking from the earthquake.
The earthquake has also changed the landscape, creating a deformation offshore 50-100km wide and 600km long that has been up-lifted by two to three metres offshore. This creates a tsunami, which spreads to the coast.
Gisborne has been physically cut off from the rest of the country by large landslides on all highways leaving the town.
The water and wastewater networks are badly damaged by the shaking, and will take weeks to restore.
Local electricity infrastructure is similarly badly damaged, and the connection to the national grid has been severed by a landslide taking down a power pylon between Gisborne and Napier.
Communications infrastructure is only lightly damaged, but communications will fail from lack of power after about eight hours running on batteries.
Remember —
■ A big earthquake such as an M9 centred in the Hikurangi subduction zone, off East Cape will be long and strong — so get gone.
■ Tsunami could arrive soon after the earthquake — there won’t be any time for an official warning.
■ It’s important to recognise the natural warning signs and act quickly.
■ In some areas it’s best to walk or bike if possible, rather than get stuck in traffic.
■ If you have family inside the evacuation zone don’t try to enter the zone to find them — this can cause traffic jams and slow down the safe evacuation of the area.
■ Trust your children’s school to carry out their evacuation plan.
■ If there’s no tsunami generated after two hours (for a local event) or Civil Defence advise you sooner, it will be safe to go home.
■ Listen to a local radio station for updates, and have a transistor radio with fresh batteries ready.
