Tag Archives: volcano

North Cerebus

Semisopochnoi goes Orange; Photo credit Matt Loewen

The North Cerebus crater at Semisopochnoi Island released a large ash plume on Sunday. It was the first confirmed emission since June 12.

Semisopochnoi has no native land mammals, but it is home to over 1 million sea birds.


Alaska Time

A landslide across Lowell Point Road, outside Seward, Alaska

A landslide blocked Lowell Point Road in Seward over the weekend. Workers began to cautiously clear the road on Monday. Lowell Point is outside Seward, and the narrow gravel road follows the shoreline of Resurrection Bay out to the point, where there are several campgrounds, lodges, resorts and B&B’s. It’s a pretty area, dominated by the beauty of Resurrection Bay. As of Tuesday, there were at least 40 cars trapped on the “wrong” side of the landslide. No word on how many travelers, who were trying to get out to Lowell Point, and now can not get to their destination.

The landslide view from the air

This post is less about the landslide, and more about giving yourself extra time when visiting Alaska, and accepting the unexpected.

This is Alaska, after all.

I’ve seen a lot of complaints online about the slide from tourists, and I know several housing accommodations have taken some flack for the road closure. No matter where you are in Alaska, and this includes Los Anchorage, you are never very far from wilderness. That is the main draw of the place.

Our infrastructure is minimal when compared with the Lower 48. Many communities have one way in and one way out. In my time in Alaska, I’ve probably seen it all: Roads closed from landslides, wash outs, beaver dams, ornery moose and/or grizzly, avalanche and wildfires. Flights delayed or rushed because of blizzards, volcanic eruptions, and pilot strikes. Sometimes, all you can do is take a deep breath, open a cold refreshment, and chill out for a day… or two…

We all have deadlines, but sometimes we find ourselves dealing with forces that have no interest in flight departures. So, if you visit Alaska, by all means, get out and explore the state, but leave the time planner at home. Enjoy both the view and the ride.


Magma Rising

Mount Edgecumbe displacement; Graphic credit: AVO

A couple of weeks ago, I posted about the swarm of earthquakes underneath Mount Edgecumbe. The numbers are in, and radar satellite data reveals a ground deformation around the volcano. Data was analyzed for the past 7.5 years, and since 2018, an uplift around Mt Edgecumbe has been constant. The peak activity, around the crater, has shown an average uplift of 3.4″ per year since 2018, and a total uplift of 10.6″.

Earthquakes in and around Mt Edgecumbe, Map credit: AVO

With the data of the ground deformation, AVO has come to the conclusion that the swarm of earthquakes is due to the movement of magma below Mount Edgecumbe, and not due to tectonic activity.

Mount Edgecumbe, a 3200 foot high stratovolcano, lies 15 miles to the west of the community of Sitka. There is no volcanic monitoring system on Edgecumbe, but there is at Sitka. AVO plans to install instruments closer to the volcano in the near future.

The rising of magma under a volcano does not necessarily mean that an eruption is imminent. The deformation and earthquakes could cease at any time. If an eruption were to occur, warning signs such as increased rate of deformation, and an increase in the earthquake swarms, would give advance warning of an eruption.


Valley of Ten Thousand Smokes

National Parks Week: Day Two

The Valley, several years after the Novarupta eruption

The Ukak River Valley was dramatically altered on 6 June 1912, when Novarupta erupted for over 60 hours. The volcanic blast was the largest of the 20th Century. Pyroclastic flows filled the Ukak Valley, which was followed by a dumping of volcanic ash. The intense heat, trapped by the ash, took decades to cool. Water, also trapped by the ash, became superheated steam, and escaped through a series of fumaroles, which inspired the renaming of the valley.

The Valley of Ten Thousand Smokes today

Photos credit: Katmai National Park & Preserve


Mount Edgecumbe

Mount Edgecumbe; Photo credit: AVO

Mount Edgecumbe is a 3200′ stratovolcano located on Kruzof Island. The volcano is approximately 15 miles from the town of Sitka, which was Alaska’s capital prior to its purchase from Russia by the United States.

Mount Edgecumbe has been dormant for at least 800 years. Recently, however, there has been a swarm of over 100 earthquakes from near the volcano. The swarm does not mean that an eruption is near, but the number is somewhat unusual. The previous two years saw only twenty quakes each year. Volcanologists are studying the data to see if these recent earthquakes are volcanic or tectonic in nature.

Tlingit oral┬áhistory has the volcano having small eruptions roughly 800 years ago. The last eruption in the geological record happened 4500 years ago. Mount Edgecumbe had a massive eruption 13,000 – 15,000 years ago. That eruption dropped dropped 3 feet of volcanic ash on what is now Sitka, and 98 feet of ash fell on Kruzof Island.

Alaska has had 90 volcanos that have erupted in the past 10,000 years. Currently, we have three that are at Level Orange and one that is at Level Yellow.


Pavlof from space

Image credit: AVO/HannahDietterich on January 19, 2022

Pavlof is one of three volcanos in Alaska at Level Orange. Orange means that the volcano is experiencing unrest, and may be experiencing an eruption with little to no ash emissions.

We have one volcano at Level Yellow, which is at an elevated unrest. It this particular case, Davidof volcano has experienced a swarm of earthquakes in the past 24 hours.


Katmai, Alaska; circa 1912

Katmai after the Novarupta Eruption; Photo was taken 9 weeks after the eruption

The eruption of Novarupta on 6 June 1912 was the largest of the 20th Century. The village of Katmai was destroyed in the eruption, buried under as much as 18 inches of volcanic ash.


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.


Historic Ash

Kodiak Island just Southeast of Katmai

Kodiak Island had a somewhat unique Winter Warning on Thursday. Mixed in the fresh snow was some ancient volcanic ash. Ash from the Novarupta eruption of 1912 was carried across the Shelikof Strait due to some high winds, and the ash came down with the recent snowfall. The ash was not expected to climb above 7000 feet, but airlines were notified, and air quality on the island may have been diminished.

Ashfall, over a foot deep, on Kodiak Island; June 1912

The Novarupta eruption started on 6 June 1912, and lasted three days. The eruption was the most powerful of the 20th Century. The ash cloud is thought to have risen to over 100,000 feet, which is incredibly impressive. An estimated 3.6 cubic miles (15 cubic KMs) of magma erupted. That’s 30 times more than the Mount St Helens eruption. As much as 600 feet of ash was dumped on the region now known as The Valley of 10,000 Smokes.

The ash kick-up does happen from time to time, when winds hit the area just right, and carry loose ash over to Kodiak.

All seven volcanos in the Katmai region, including Novarupta, remain at Level Green.


Atka Volcanic Complex

Earthquake activity on Atka Island

The southern portion of Atka Island is older than the north, with some volcanic rock dating back 5 million years. The active northern part of the island once had one large cone, which was lost in a large eruption, and is now peppered with several smaller volcanos.

A volcanic complex can have several vents, and a widely varying composition of lava. Seismic activity within a complex can be difficult to pinpoint the source of the activity. Which vent is rumbling now? Some of those smaller vents have developed into stratovolcanoes.

Korovin Volcano has been very active in recent times, while Mount Kliuchef last erupted in 1812. The Atka Complex recently was elevated to a Level Yellow, due to seismic activity on the island. Interestingly, the swarm of activity is not near the known suspects, but several kilometers the the west and southwest, and approximately 10 miles from the community of Atka.

Source: AVO