Daily Archives: 17 January 2022

Hunga Tonga Eruption

An undersea volcano erupted Saturday near the island of Tonga. The satellite imagery above is pretty intense, and the ash plume reached 20km above the earth.

Tsunami alerts were put out almost immediately, and the island of Tongatapu had waves flooding into the capital.

Courtesy of NWS/NOAA

The tsunami reached Alaska’s southern coast this morning, with King Cove recording the highest waves at 3.3 feet.

Air pressure change

That wasn’t the only wave to hit Alaska from the eruption. The shock wave of the event caused a drastic air pressure change over the state as well.

Courtesy of the NWS and NOAA

Can you hear a volcano erupt from almost 6000 miles away? It turns out that you can. Many people, who were up between 3:30-4:00 am on Saturday reported hearing a sonic boom. It’s telling that many Alaskans initially reported being awaken by a large boom, and most of them assumed it was a “moose on the porch”. Various infrasound recorders placed around the state by Alaska Volcano Observatory confirmed that the sound heard was the volcanic pressure wave, not a moose.

I find that absolutely fascinating.

A second eruption pressure wave traveled over Anchorage 19.3 hours after the first wave, traveling in the opposite direction.

As of this writing, details of the damage remained sketchy at best. It is known that waves entered Tonga’s capital, and that a thick layer of volcanic ash was dumped on the island. No deaths have been reported at this time, and it is not known how many islands have seen damage from tsunamis or ash fall. Tonga’s internet service, much like Alaska, is served via undersea cables. It is thought that those cables were damaged in the eruption.

New Zealand has sent military aircraft to Tonga to assess the damage.