Big, four-headed volcano

The potentially explosive Islands of Four Mountains now thought to all be part of one massive volcano/NASAIsland

The potentially explosive Islands of Four Mountains now thought to all be part of one massive volcano/NASA

With one natural phenomenon already ravaging the globe in the form of the newly evolved SARS-CoV-2 virus, scientists are now warning they might have found the potential for another natural disaster far out in the Aleutian Arc of islands probing the Pacific Ocean off Alaska’s western coast.

As with the biologists who warned of pandemic viruses in the years before SARS-CoV-2 spawned the disease COVID-19 which has now killed more than 1.5 million and counting, the vulcanologists studying the Islands of Four Mountains says there are indications of a monstrous caldera beneath them that could explode any day.

The only good news is that vulcanologist, unlike biologists, measure time in geologic years not human life spans. So their version of any day could range from tomorrow to 10,000 or more years from now.

Still, if what they think is brewing beneath the 5,675-foot Cleveland Volcano and the volcanoes surrounding it is real, there is potential for Mother Nature to once again unleash her wrath on humankind.

John Power, a U.S. Geological Survey Scientist who works at the Alaska Volcano Observatory said on Wednesday that there appears the possibility for an eruption on the scale of Krakatoa or bigger.

Power is the lead author on a paper discussing the findings that caused a stir at the fall meeting of the  American Geophysical Union. It suggests the four mountains of the islands are all only separate heads on one huge volcano.

To date, the area has been best known for its centerpiece – Cleveland Volcano – periodically spouting ash that has forced aircraft bound from the U.S. to Asia to alter their flight paths. The paper suggests much bigger problems could be brewing.


Geologist and writer David Bressan has labeled Krakatoa (also sometimes called Krakatau) the “first global catastrophe” in part because of the number of people it killed, in part because of the visible ash it injected into the sky around the globe, in part because of the global climate changes that followed, and in part because the telegraph had just connected media around the globe for the first time thus allowing them to stir a global tizzy.

“Today Krakatau explodes in movies, books documentaries and even comics,”wrote at Forbes in 2016. By contrast, the eruption of the Tambora only 70 years earlier and in the almost same region is almost forgotten today, despite being more powerful. At the time only some local western merchants and diplomats recorded that eruption and only one year later an account of the catastrophe was published in the little known History of Java by British governor of Indonesia and naturalist Sir Thomas Stamford Bingley Raffles.”

Tambora did eventually get its due. It is now credited for the year without a summer in the Northern Hemisphere.

In 1816, Evan Andrews writes at, “the Northern Hemisphere was plagued by a weather disruption of seemingly biblical proportions. Following a relatively ordinary early spring, temperatures in the eastern United States plunged back below freezing, and communities from New England to Virginia experienced heavy snowfalls and crop-killing frost during June, July and August. Europe also found itself in the grip of an unseasonable chill. Winter snows refused to melt, and between April and September, some parts of the Continent were drenched by as many as many as 130 days of rain. The unrelenting gloom inspired author Mary Shelley to write her famous novel “Frankenstein,” but it also wreaked havoc on farmers. Crops failed across Europe and China, spawning deadly famines and outbreaks of typhus and other diseases.

“At the time, many people believed the chaos was some form of divine retribution, but most scientists now place the lion’s share of the blame on an Indonesian volcano called Mount Tambora.”

The belief was and is that Tambora shot so much dust and ash into the atmosphere that it caused what would later come to be known as “nuclear winter” as scientists warned of the danger of a global nuclear war generating the kind of catastrophe that has to date been reserved for nature. 

The consequences of huge volumes of dirt and dust being kicked into the atmosphere, for whatever reason, make global warming look like child’s play. A meteor strike that filled the planet’s atmosphere with dust and ash is credited with destroying the dinosaurs that roamed the planet before mammals, including humans, took over.

Powers is not expecting anything like that out of the Island of Four Mountains any time soon though there has been some pretty wild speculation.

Super Volcanoes

The website ScienceAlert suggested the Island of Four Mountains might be hiding “Alaska’s version of Yellowstone’s Super Volcano.”

Scientists studying that pool of molten rock beneath Yellowstone National Park in 2019 speculated, according to Medical Daily, that an explosion there “might annihilate more than five billion people in the course of the most massive eruption in history.

“The Yellowstone supervolcano…in Wyoming is mathematically overdue for another devastating eruption. This eruption is predicted to render two-thirds of the United States uninhabitable and wipe out most of the world’s population.”

Other scientists later dismissed that idea, and it’s a big stretch from the Yellowstone supervolcano to Four Mountains given how little is known at this point, Power said.

The data on what lies beneath the islands is limited, he said, noting that “it’s kind of only by happenstance we stumbled on this.”

“A lot of people have asked how dangerous it is,” he added. “We don’t know. That’s the short answer.”

The long answer is that it’s complicated. The indications are the structure beneath the islands is similar to that beneath Krakatoa or Tambora, but a whole lot more data is needed to confirm that.

An expedition to the area was planned for last summer, but it was scuttled by the pandemic. Power is hoping vulcanologists can get to the area next summer. Meanwhile, “we’ve got a couple of ways we’re trying to move forward,” he said.

Satellite monitoring can track the islands’ temperature and provide some visual information and there are a couple of remote seismic stations in the area to monitor ground movements. The islands themselves are uninhabited and a long way from nowhere.

The nearest community is Nikolski, an outpost of 18 residents living in 12 homes on Umnak Island about 50 miles to the east. The island is home to more sheep, cattle and horses than people. The only way to get there is by small plane to an unlighted gravel airstrip owned by the U.S. Air Force. There is no port. Provisions are delivered once or twice per year by barge and have to be lightered about three miles to shore because of shallow water. 

The nearest community of any size is Unalaska/Dutch Harbor, a busy though remote fishing port home to about 4,400 another 120 miles to the east.

An old U.S. Naval Station on Adak Island is about 250 miles to the west. It is home to a struggling fishing processing plant and serves as a refueling stop for some Bering Sea fishing boats. The population has shrunk from about 6,000 when the Naval Air Station was in operation to about 300 today.

The area itself is about 1,000 miles from Anchorage, or about the distance from New York to St. Louis.

Deadly history

A smallish, volcanic island in the Pacific about 100 miles west of Jakarta, Indonesia, Krakatoa killed more than 36,000 people when it exploded in August 1883, but that was only the beginning of global impacts.

The mountain’s explosion – later judged to be 10,000 times more powerful than the nuclear bomb that destroyed the Japanese city of Hiroshima during World War II – hurled five to 11 cubic miles of rock, ash, dust and debris into the atmosphere and generated shock waves that rippled around the planet seven times.

The sunlight-blocking effect of all that dirt in the atmosphere lowered global temperatures for half a decade, according to the National Oceanic and Atmospheric Administration, and played all sorts of havoc with climate.

Southern California witnessed recorded rains not to be matched until 2005 when The New York Times headlined that “A Season of Mud and Death In California Continues.”

The population of California in 1880 was 865,000 people, not much bigger than the population of Alaska today, according to the U.S. Census. The state had swollen to 36 million by 2005.

The global consequences of a Krakatoa-like explosion today would likely be far worse than in 1880 simply given the quintupling of global population from around 1.5 billion in the mid-1800s to 7.8 billion today.

And if the explosion was bigger than Krakatoa?

Well, one could think in COVID terms. Even the little things Mother Nature does can have huge consequences.






5 replies »

  1. Almost exactly 100 years before Krakatoa, in June of 1783 the Laki or Lakagígar volcanic fissure opened up a 15.5 mile long valley of 130 calderas that spewed forth around 3.5 cubic miles of basalt with lava fountains reaching almost a mile high over an eight month period. Needless to say the amount of gases belched into the atmosphere from this fissure caused all kinds of global impacts.

    We live on a world that is alive and it holds many wonders, both awesome and frightful.

  2. Krakatoa also unleashed the loudest noise ever. It was so loud it was heard 3,000 miles away, that’s about the distance from Anchorage to Detroit, or Anchorage and Sapporo Japan. That’s amazing!

  3. Would be a pretty big caldera, as the outside shore to shore distance between Cleveland and Uliga Island is 35 km. Include in Herbert Island farther to the SW and that distance grows to 50 km. The largest Yellowstone caldera is 65 x 80 km. Toba in Indonesia measures 30 x 100 km. The suspected Apolaki caldera to the east of the Philippines is 150 km in diameter. Largest one in the Aleutians is Fisher at 11 x 18 km.

    Calderas form two ways: Explosively and via non-explosive collapse. All the Aleutian calderas I know of are explosively formed with Katmai – Novarupta in 1912 being the most recent. And there are a lot of them. The non explosive calderas generally take place on top of volcanoes when magma withdraws. Mauna Loa in Hawaii or Olympus Mons on Mars are good examples.

    If these guys are correct, and there is indeed a large magma body under these islands, if anything exciting happens, the resulting eruption will be violent, as there is a LOT of water available and magma and water don’t play well together. Neat research, though. And I thought the science was settled (/sarc). Cheers –

  4. Craig,
    Great article.Saw this topic posted on a science blog.
    Isle of 4 mtns,is an area that has to be seen to truly appreciate its uniqueness.
    Ive transited the area many times back in the day,The seas are normally scoured by incredibly strong tides.Slack water if any is normally measured in minutes.
    The bottom is covered in expansive Red,Black and bamboo corals.
    Ivan Veniaminof has documented verbal history of Atka villagers rowing to Unalaska Island to make war,and visa versa.
    The distances aren’t staggering,but the risks were.
    Segaum pass to the west can be one of the nastiest passes in a bad storm ,amplified by a running tide
    There are times when the area around the Islands can be becalmed for 100’s of square miles.
    Masking the well known and deserved notoriety

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