Media statement #6 – 1340 AEDT Fri 5 March 2021
A Tsunami Marine Warning remains in place for Norfolk Island following an 7.9 magnitude earthquake north east of New Zealand early this morning. A further aftershock of 6.6 magnitude was recorded at 1013 AEDT at the same location
A marine warning means there is the possibility of dangerous rips, waves and strong ocean currents and some localised overflow into the immediate foreshore for Norfolk Island.
The Joint Australian Tsunami Warning Centre advises there is no current tsunami threat to the Australian mainland or to Lord Howe Island.
Tsunami waves are more powerful than beach waves of the same size. It is the power rather than the height that makes tsunami waves so destructive, hence dangerous to swimmers and boaters
At Norfolk Island, the bay next to the island’s pier was observed to ‘fill up” with the water level rising to be an estimated 30-60 centimetres. This lasted a couple of minutes then subsided, before repeating about 10 minutes later. A sea level gauge at Norfolk Island recorded a 64 centimetre tsunami wave earlier this morning.
Small tsunami waves have been recorded in some areas of the east coast of the mainland, but were not considered dangerous. In NSW a 10 centimetre tsunami wave was observed at Tweed Heads while at Port Kembla near Wollongong the sea level gauge recorded a nine centimetre tsunami wave.
While small tsunami waves could arrive along east coast of the mainland in coming hours, they are not expected to be dangerous. Hence there is no warning for mainland Australia or other offshore locations.
While the warning remains in place for Norfolk Island, residents are strongly advised to stay out of the water and move away from the immediate water’s edge of beaches, marinas, harbours, coastal estuaries and rock platforms.
The threat is expected to persist for at least the next two hours.
In New Zealand, the warning authority there has assessed that the largest waves have passed and the threat level has been downgraded to a Beach and Marine threat for all areas.
In New Caledonia’s Isle of Pines tsunami waves were reported to penetrate over 30 metres inland
Further overseas, the following tsunami wave heights have been recorded: Vanuatu (32 centimetres), Fiji (13 centimetres), Cook Islands (8 centimetres) and Tonga (6 centimetres).
The Australian public is advised to check the latest advice on the Bureau’s twitter or at www.bom.gov.au/tsunami