Sea change: the science behind the new tsunami messaging

Recently, the Pacific Tsunami Warning Center (PTWC), based in Hawai'i*, announced important changes regarding messaging about tsunami and their warning system. We sat down with our fearless and very busy Director at GeoNet, Dr. Ken Gledhill, who is also the Chair of the Pacific Tsunami Warning and Mitigation System, to find out about these changes. 

Q. What was New Zealand’s scientific community’s involvement in the changes to the system?

A. New Zealand scientists and emergency managers have been involved in leadership roles in the development and testing of these enhanced products for the PTWC tsunami warning messages. We trialed this new system on behalf of the PTWC and moved it from science to practice.

Q. Why did these changes happen?

A. The changes in the system started, in part, because of the Boxing Day tsunami in the Indian Ocean in 2004. Since that tragic event, there have been huge advances in our ability to forecast the impacts of tsunami once we have the necessary data on the earthquake which caused the tsunami. This allowed New Zealand to move to a system using forecast models to estimate the tsunami threat in pre-defined coastal zones around New Zealand some years ago, supported by the modelling capability of GNS researchers and our collaborators. This is the system now being rolled out more widely in the Pacific.

This exciting innovation in science is very meaningful to everyone involved: it can help save lives by providing accurate and timely information when we most need it.

Time is the critical factor in successful tsunami response.

Q. How will this affect our science response to tsunami?

A. The main benefit of this new system to our science response will be the availability of extra information to use in our initial and on-going assessments; we will have more information to confirm our threat levels. Our procedures using the Tsunami Expert Panel (TEP) of New Zealand scientists and New Zealand-based modelling will not change, but the other main benefit is that there will be less confusion between what PTWC messages and the information coming from the Ministry of Civil Defence & Emergency Management (MCDEM).

Q. What is the role for GeoNet regarding tsunami warnings?

A. GNS Science (via GeoNet) is the scientific advisor to MCDEM on all geological hazards including tsunami. We activate the TEP and usually will provide a science advisor to the National Crisis Management Centre. We have all worked together for years and our duty officers are also in constant contact with each other during tsunami events that could impact New Zealand.

Q.  What changes will the public notice?

A. The major changes is that terms like ‘Warning’ or ‘Watch’ will no longer be used in PTWC messages. Instead they will now provide ‘Threat forecast levels’.

MCDEM are, as always, the authoritative voice for tsunami advice in New Zealand.

It is important to remember that we may not always get warnings about tsunami. The MCDEM'S advice if you are on the coast and experience any of the following, is to move immediately to the nearest high ground, or as far inland as possible:

  • Feel a strong earthquake that makes it hard to stand up, or a weak rolling earthquake that lasts a minute or more;
  • See a sudden rise or fall in seal level
  • Hear loud and unusual noises from the sea

*Note: This is the correct spelling of Hawai'i in the Hawaiian language, one of the TWO official languages of Hawai`i. 

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