It's now 3 years on since the Hunga Tonga–Hunga Haʻapai 'VEI 6' submarine explosion that reached 57km into the mesosphere, sending pressure waves and tsunamis around the globe. Locally, sonic booms were heard from pressure waves with substantial damage occurring to marine vessels on Tutukaka harbour from the tsunami waves. A 1.33m tsunami wave was recorded at Great Barrier Island.
Here are some of the discoveries over the last 36 months of pre and post eruption.
15 minutes before the major eruption, precursor 'Rayleigh waves' were detected by seismometers in Fiji and Futuna. The seismic waves were the equivalent of a M4.9 earthquake and was a warning from the volcano on what would come next. An important discovery for future early warning systems.
The eruption caused the largest 'dirty thunderstorm' in modern recorded history with 2,600 lightning flashes per minute and nearly 400,000 lightning strikes while the eruption was ongoing.
The tsunamis were triggered by water displacement and fast-moving atmospheric pressure disturbances. The latter was the reason for earlier than expected tsunami waves at Great Barrier Island.
The air chemistry change in the stratosphere initially produced vivid colours in the sky at dawn and dusk but has also led to a temporary reduction in the ozone layer.
·Water vapour remains trapped in the upper stratosphere, triggering a warming effect on the earth surface temperature on a global scale. As of 31st December the earth's surface temperature is +0.34 above January 2022.
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