Summary

The 15 January 2022 Hunga-Tonga-Hunga-Ha'apai Eruption generated a tsunami that caused damage locally, regionally, and across the Pacific. Waves up to 15 m high hit the west coasts of the Tongatapu Islands, ‘Eua, and Ha’apai Islands (Government of Tonga), and elsewhere waves up to 2 m in amplitude were reported by the Pacific Tsunami Warning Centre (PTWC).  To save lives, countries issued warning and advisory alerts, and in some places evacuated coastal populations.  Altogether, the PTWC issued 12 bulletins over a 20-hour time span and reported 117 tsunami wave measurements from 26 countries. 

The gigantic explosion, heard by several countries in the region, obliterated the subaerial remnants of the island, generating an atmospheric disturbance that extended into the stratosphere and that was observed by international satellites.  The explosion also generated a pressure wave that traversed the globe, and in some places coupling with the ocean surface caused the generation of small tsunami waves observed  in the Caribbean, Atlantic, and the Indian Ocean.  

Previous eruptions were in March 2009 and November-December 2014, but none of them generated tsunamis. The volcanic activity resumed in December 2021.  On 13 January, a smaller eruption occurred for which the Tonga NTWC issued a tsunami advisory lasting about one day – the advisory was cancelled at 1102 local time.  Unfortunately, while the potential for continued volcanic activity was expected, a gigantic eruption was not planned for.

This is the first time that the PTWS has had to respond to a destructive volcanic event of these characteristics as the PTWS has primarily focused on earthquake-generated tsunamis that cause nearly 90% of the world’s tsunamis.  To move forward, the PTWS is immediately convening Post-Event Briefs to share information and experience, and provide interim guidance should another volcanic eruption occur.

For more information, please visit the 15 January 2022 event website at: http://itic.ioc-unesco.org/index.php?option=com_content&view=article&id=2186:15-january-2022-hunga-tonga-hunga-ha-apai-volcanic-eruption-and-tsunami&catid=2664&Itemid=3265