Early warning systems on Raoul Island, one of New Zealand’s most integral sites for monitoring earthquakes and tsunami, will undergo critical repairs after an earthquake occurred in the area last Friday, 5 March.

The tidal gauge at Raoul also provides critical early warning for the Pacific Islands. (A tsunami wave can travel from Raoul to Tonga in less than an hour.)

Small teams from New Zealand’s MetService and GNS Science are on their way to the island on board the Royal New Zealand Navy ship HMNZS Canterbury. On arrival, they will be flown to shore along with equipment and provisions by navy and air force helicopters.

According to crew on a RNZAF P-3K2 Orion that flew over Raoul Island on Saturday, there was no significant damage to equipment or structures but they saw landslips and water discolouration. 

Maritime Component Commander Commodore Mat Williams said Friday’s earthquakes and tsunami warnings were a reminder of how important these early warning systems are.

“We will continue to monitor the situation in the Kermadec Islands, including consulting with our colleagues in GNS Science.”

Work on the island includes critical repairs to GNS equipment and attempt to improve power systems. 

The two tsunami gauges located on Raoul Island provide information about any tsunami caused by an earthquake and act as an early warning system, said GNS Science Remote Infrastructure Operations Coordinator Kris O’Brien.

Routine maintenance work will also be carried out on the automatic weather station, as well as replacing a 60-year-old weather balloon launching facility.

Steve Knowles, MetService’s Network Observations Manager said the balloon launching facility will improve safety for Raoul Island Department of Conversation staff who launch meteorological balloons on behalf of New Zealand’s MetService.

“The balloon data contributes to global weather models and adds another layer of data to help in the tracking of tropical cyclones.” 

“MetService’s Raoul Island Automatic Weather Station, which measures atmospheric pressure, rain fall, solar radiation, bright sunshine hours, temperature, wind speed and direction, will also be checked and serviced to ensure continued trouble-free operation and transmission of data back to our Wellington HQ.”

In addition, two meteorological buoys recovered from Northland beaches will also be redeployed en route. The free-drifting buoys provide atmospheric pressure, sea surface temperature and ocean current data.

This is the first major resupply mission since March 2020 when Department of Conservation staff left the island.

Tsunami warnings for Pacific Islands

Last week, on March 5 at 1928UTC, a Pacific tsunami was generated by magnitude 8.1 earthquake, at a depth of 10 kilometres, in the Kermadec Islands (Lat: 29.6 S Lon: 176.0 W) about 1000 kilometres north east of New Zealand.

A tsunami wave of less than 0.30cm was recorded at the Fishrock Tidal Gauge at Raoul Island at approximately 9:45am.

Tonga Met confirmed that a small tsunami wave of of 0.05m (0.2ft) was monitored at a Nuku'alofa tidal gauge at local time 10:29am (UTC 2129).

An hour later at 11:30am, the Niutoputapu tidal gauge in the far north of Tonga, also recorded 0.05m.