Tonga – Hunga Tonga eruptionTechnical assistance to the Government of Tonga for volcanic activity

Overview

In December 2014 a volcanic eruption commenced in the vicinity of the islands of Hunga Ha'apai and Hunga Tonga (hereafter known as the Hunga area), approximately 65 km north-west of Nuku'alofa, Tonga. Over the next week GNS Science, Ministry of Lands and Natural Resources, Tonga (MLNR) and NZ MetService discussed the activity, using observations from Nuku'alofa and data observed from satellites, in an effort to try to better understand the potential impacts of the eruption on Tonga and to provide data for NZ MetService for its modelling of volcanic ash in the atmosphere and its potential impact on aviation.

During this period the wind was largely from the east, blowing any ash away from Tonga, but by the first week of January the wind direction near the volcano started to blow from the north-west, which carried ash towards the island of Tongatapu and airline flight paths. The Tongan government subsequently requested assistance from New Zealand and resulted in this project.

The project aimed to

• assist the Tongan Government to assess volcanic activity and potential impacts after an underwater eruption in the vicinity of the islands of Hunga Tonga and Hunga Ha'apai (hereafter known as the Hunga area)
• provide technical assistance to MLNR and Tonga MetOffice to help with its general volcano monitoring activities through training and advice
• mitigate future impacts of volcanic activity on aviation, especially flights to/from New Zealand, by assisting MLNR and Tonga MetOffice improve the flow and quality of information to the Wellington Volcanic Ash Advisory Centre (VAAC)

To achieve these objectives, we

• worked with Tongan authorities to facilitate two observation visits to the Hunga area with Tongan Government representatives, assessed the location and size of the eruption and its impacts on the surrounding area, and then used those observations to better understand the nature of the eruption and its potential impacts on Tonga, particularly on domestic and international aviation
• trained MLNR and Tonga MetOffice in how to make observations of volcanic activity; specifically, what to look for and how to record those observations, as well as how to communicate those observations via reports and briefings to the Tongan Government, NZ MetService and media
• worked with MLNR and Tonga MetOffice to understand their procedures for dealing with airline reports of volcanic ash and provided advice on how they could be improved
• provided first-hand information to NZ MetService to help with aviation ash forecasts and to Air New Zealand for planning flight schedules

Outcomes of this project

1. Tonga is better able to observe and assess volcanic activity and its potential impacts.
2. Tonga has improved the information it sends on the presence (or absence) of volcanic ash in the atmosphere to the Wellington VAAC, resulting in more reliable volcanic ash forecasts for aviation.
3. Tonga has improved its general understanding of how to monitor volcanoes.