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The tsunami procedures and products, which are carried out by the Pacific Tsunami Warning Centre (PTWC) for the Pacific Tsunami Warning and Mitigation System, were immediately developed after the catastrophic eruption of the Hunga-Tonga Hunga-Ha’apai volcano on 15 January 2022 and ensuing tsunami to respond to the possibility of future tsunamis generated by HTHH volcanic activity.

On the afternoon of 15 January 2022, the Hunga Tonga – Hunga Ha’apai (HTHH) Volcano, located about 70km northeast of Tongatapu, Tonga, violently erupted. The massive explosion generated a damaging tsunami that impacted locally, regionally, and across the Pacific. International satellites captured the gigantic explosion, and countries in the region heard the loud blasts.  The eruption severed the fiber communication cable from Tonga to the outside world, and pushed the island nation into a communication blackout for six weeks.

“The Hunga Tonga – Hunga Ha’apai volcanic eruption and tsunami was unprecedented.  When the fiber optic cable broke, all tsunami- and volcano-monitoring observations from Tonga stopped, leaving every PTWS National Tsunami Warning Center ‘data blind’ and having to make tsunami warning decisions without knowing the severity of Tonga’s tsunami,” explains Dr Laura Kong, Director of the International Tsunami Information Center (ITIC), a partnership between UNESCO and the U.S. National Oceanic and Atmospheric Administration.

PacWave22-PICT replayed the 15 January 2022 HTHH volcanic eruption and tsunami using specially-developed message products to enable countries to test their volcano tsunami response Standard Operating Procedures (SOPs), and also test regional communication systems for sharing warning and response information amongst national tsunami warning centres, national disaster management offices, and geological hazard observatories. 

“More than ever, this stresses the crucial importance of regional cooperation and information sharing.  If one nearby country is able to share its tsunami observations and assessment with others, it’s going help those countries make better warning decisions that will save lives,” highlighted Vladimir Ryabinin, Executive Secretary of the Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO), the United Nations body responsible for global and regional coordination of tsunami early warning systems and preparedness activities.

IOC-UNESCO coordinates the larger Pacific Wave 2022 Exercise, which includes the PacWave22-PICT table top simulation of the HTHH volcano eruption as well as various other regional simulations taking place between 1 September and 30 November 2022. The Pacific Wave Exercises take place every two years to test the Pacific Tsunami Warning and Mitigation System, the response of national tsunami warning centres, as well as country preparedness arrangements and operational procedures to respond and recover from a destructive tsunami. 

Learning from the HTHH event, where much of the information immediately available was through social media, The Pacific Wave 22 Exercise demonstrated that real-time sharing of official information within and across countries in the region was valuable for national tsunami alert decision-making.  Information sharing methods included a dedicated E-mail listserv (hosted by ITIC), a WhatsApp group (hosted by UNESCO and the French Polynesia’s Centre Polynésien de Prévention des Tsunamis) and, high-frequency Radio in various countries.

“This PacWave22-PICT regional exercise, dedicated to Pacific Island Countries and Territories, was the 1st of its kind and it was a good opportunity for us to build regional cooperation and direct links between countries,” said Anthony Jamelot, Geophysicist, Centre Polynésien de Prévention des Tsunamis.

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 (ITIC)