Urgency Response to the 15 January 2022 Hunga Tonga - Hunga Ha'apai Volcanic Eruption -understanding the Volcanic Mechanism and Impact of the tsunami

Lead Research Organisation: British Geological Survey
Department Name: Earth Hazards & Observatories

Abstract

On January 15th, 2022, a month into the eruption of Hunga Tonga - Hunga Ha'apai volcano, located in the Tonga Island arc in the southwest Pacific, there was a short lived (two hour), extremely high intensity explosive eruption that destroyed most of the subaerial parts of the volcanic edifice. The resulting pressure wave and tsunami impacts were local and global, and the most far-reaching since the eruption of Krakatau volcano in 1883. Tsunami waves striking the nearby (65 km) low-lying coasts of Tongatapu Island, were up to 15 m high. Because of well organised early warning and evacuation, there were very few (three) fatalities, although there was significant destruction along coastal areas. The low-lying islands of the more distant Nomuka Group were completely overwhelmed, and villages destroyed. Farther afield from the Tongan islands, the tsunamis were caused by the massive atmospheric pressure wave, that is the first instrumentally recorded eruption-generated event of this scale, which affected the entire global atmosphere and ionosphere, causing the observed infrasound waves and unusual long-period seismic resonances.
The Hunga Tonga - Hunga Ha'apai eruption was a major surprise and there remains a major uncertainty over the mechanism(s) and the generation of the local tsunamis striking the nearby Tongan islands coasts, with three possibilities considered 1) pyroclastic density currents resulting from the collapse of the 50 km high ash column resulting from the explosion, 2) submarine mass sediment movements associated with the destruction of the volcanic edifice, and/or, 3) the massive shock wave resulting from a phreatomagmatic explosion as sea water entered the fractured volcanic caldera.
The objectives of the proposed research, therefore, are to identify from very high resolution (one metre) satellite images the volcanic mechanism (s) of the eruption and the impact (inundation, height, and destruction) of the tsunami on the nearby Tonga islands. To achieve these aims, we will use the satellite imagery, 1) to map the morphological changes of Hunga Tonga - Hunga Ha'apai volcano in the build-up to and during the eruption; 2) as basis for observations on the eruption mechanism and its impacts, particularly information on the timing of the events, and 3) identify the height and inundation of the tsunami on the Tongan islands together the resulting destruction.
After previous recent tsunamis, such as those of 2018 in Indonesia, the impacts on coastal areas were mapped soon after the event from field work by multinational teams that recorded the destruction and inundation. A major challenge with the Hunga Tonga - Hunga Ha'apai event, however, is the ongoing lack of information on the tsunami impact from Tonga because the eruption fractured the internet communications cable connecting the country to the outside world - so since the eruption the Island Kingdom has been largely isolated. It is also because Tonga is in Covid lockdown, with no access for foreign (non-Tongan) visitors.
Our use of satellite imagery to map the tsunami impact, therefore, is a novel approach, not used previously in mapping tsunami inundation immediately after an event. The eruption has resulted in a major programme of scientific research carried out by many scientific organisations with who we are co-ordinating. We are also co-ordinating as far as possible, with local scientists, who will provide observational information on the tsunami impact to validate the interpretations of satellite data. These interpretations, in addition to validating the tsunami modelling, will also be used to underpin mitigation of the tsunami impact.

Publications

10 25 50
 
Description Failure mechanism and tsunamigenesis of the Anak Krakatau landslide on 22 December 2018
Amount £61,756 (GBP)
Funding ID NE/T002034/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 04/2019 
End 04/2019
 
Description Submarine landslide tsunamis, mechanisms of granular flows at multiple scales; a new UK/China multidisciplinary research collaboration
Amount £45,637 (GBP)
Funding ID NE/W004593/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 07/2021 
End 07/2024
 
Title Tsunami trimlines identified across different islands of the Tonga archipelago 
Description Tsunami trimlines identified across different islands of the Tonga archipelago. Trimlines have been used as a reference land feature following the January 2022 Tonga tsunami event that ripped off vegetation and built-up areas. Trimlines are distinctive limits between an area with sand coverage, vegetation destruction, and soil erosion on the one hand, and the unaffected natural vegetation on the other. This distinction provides a good landmark to map the inundation width and the landward extension of tsunami runup. In this case, the trimlines have been manually delineated by BGS - Earth Observation team using different high-resolution satellite datasets both optical (KompSat, Planet, Pleiades, WorldView) and radar (TerraSAR-X). Trimlines are well known from task-force publications documenting recent tsunami detection efforts and provide key information to support tsunami triggering mechanism models. For more info, see https://www.usgs.gov/media/images/tsunami-terms and Scheffers et al. (2012), https://doi.org/10.1007/s11069-010-9691-6 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://www2.bgs.ac.uk/nationalgeosciencedatacentre/citedData/catalogue/e8926a1a-305a-441d-a0d8-7f6c...
 
Title Waterlines delimiting the edge of the Hunga Tonga - Hunga Ha'apai island between April 2017 and April 2022 
Description Waterlines have been extracted to delimit the edge of the Hunga Tonga - Hunga Ha'apai island between April 2017 and April 2022. Waterline is defined as the instantaneous land - water boundary at the time of the imaging process. Waterlines have been generated by BGS - Earth Observation team through a thresholding-based classification based on Sentinel-2 multispectral imagery and developed on Google Earth Engine. Specifically, the thresholding has been applied to the Normalized Difference Water Index (NDWI) has been derived as a basis to discriminate between the land and sea based on their spectral characteristics. Changes in waterlines over volcanic islands can provide key information to understand volcanic processes. For more info on the methodology, see Novellino et al. (2020) https://doi.org/10.3390/app10020536 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://www2.bgs.ac.uk/nationalgeosciencedatacentre/citedData/catalogue/1a7715dd-9adb-4a44-ad87-75ca...
 
Description Large volume eruption tsunamis - Birmingham 
Organisation University of Birmingham
Country United Kingdom 
Sector Academic/University 
PI Contribution Expertise in eruption volcanology
Collaborator Contribution Extensive experience in volcanic eruption processes
Impact Improved understanding of eruption processes contributing to tsunami generation
Start Year 2018
 
Description Large volume eruptions Krakatau URI 
Organisation University of Rhode Island
Country United States 
Sector Academic/University 
PI Contribution Sedimentary and hydroacoustic data to support numerical tsunami modelling
Collaborator Contribution Numerical tsunami modelling
Impact Preliminary numerical models of volcanic landslide tsunami
Start Year 2018
 
Description NOC 
Organisation National Oceanography Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution Scientific input, paper writing, staff participation in marine surveys and onland field work, attendance at meetings
Collaborator Contribution Project leadership, organisation, collaboration, peer reviewed paper writing
Impact Field reports, peer reviewed papers, PhDs, media interest.
Start Year 2012
 
Description Scientific collaboration 
Organisation University of Glasgow
Department James Watt Nanofabrication Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution Scientific understanding of tsunami generation from nonseismic mechanisms
Collaborator Contribution Numerical understanding of granular flows
Impact Improved understanding of submarine landslide tsunami numerical models
Start Year 2021
 
Description Scientific collaboration 
Organisation University of Glasgow
Department James Watt Nanofabrication Centre
Country United Kingdom 
Sector Academic/University 
PI Contribution Scientific understanding of tsunami generation from nonseismic mechanisms
Collaborator Contribution Numerical understanding of granular flows
Impact Improved understanding of submarine landslide tsunami numerical models
Start Year 2021
 
Description University of Auckland, New Zealand - Identifying the tsunami mechanism of the HT-HH eruption and its impact 
Organisation University of Auckland
Country New Zealand 
Sector Academic/University 
PI Contribution Interpretations of satellite imagery of the HT-HH volcano and tsunami impact on adjacent islands
Collaborator Contribution Interpretations of the HT-HH eruption mechanisms
Impact Improved understanding of the HT-HH eruption, its tsunami and impacts
Start Year 2022
 
Description University of Birmingham - Identifying the tsunami mechanism of the HT-HH eruption and its impact 
Organisation University of Birmingham
Country United Kingdom 
Sector Academic/University 
PI Contribution Interpretation of satellite imagery of the HT-HH volcanoc and impact of the tsunami on adjacent coastlines
Collaborator Contribution Interpretation of eruption mechanisms
Impact None as yet
Start Year 2019
 
Description University of Rhode Island - Understanding the tsunami mechanisms from the HT-HH eruption of 2022 
Organisation University of Rhode Island
Country United States 
Sector Academic/University 
PI Contribution Understanding of the geological mechanisms of the HT-HH eruption and pre-eruption bathymetry of the volcano and local environs
Collaborator Contribution Numerical tsunami models
Impact paper on the eruption mechanisms in preparation
 
Description Interview for international news - SKY 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with SKY news to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with NEWS Discovery New Zealand to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with TOP Chinese News media to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with Pacific Media Network, New Zealand, to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with ABC radio, Australia to understand the tsunami mechanisms and impact of the HT-HH volcanic erutpion
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with BBC News Channel to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with Sky News to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with Television of Serbian diaspora to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022
 
Description Interview to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with National Public Radio, Washington DC, to understand the tsunami mechanisms and impact of the HT-HH volcanic eruption
Year(s) Of Engagement Activity 2022