Dozens of earthquakes swarm Hawaii as the world's largest volcano erupts

The lava-filled Moku'āweoweo caldera as captured by the USGC webcam.
The lava-filled Moku'āweoweo caldera as captured by the USGC webcam. (Image credit: US Geological Survey)

Hawaii's Mauna Loa, the world's largest active volcano, is erupting for the first time in nearly 40 years. 

Dozens of earthquakes — one of them a magnitude 4.2 quake — have swarmed the region after the volcano's Moku'āweoweo summit caldera erupted on Sunday (Nov. 27) night. Officials have issued an ashfall advisory for Hawaii's Big Island and residents have been asked to remain vigilant. 

So far the eruption's lava flows pose no risk to people living downhill from the eruption and air travel is currently unaffected, according to Hawaii's Tourism Agency. (opens in new tab)

"At this time, lava flows are contained within the summit area and are not threatening downslope communities," officials from the U.S. Geological Survey (USGS) wrote in a hazard notification (opens in new tab). They warned, however, that, "based on past events, the early stages of a Mauna Loa eruption can be very dynamic and the location and advance of lava flows can change rapidly." 

Related: Satellites watch Mauna Loa, world's largest active volcano, erupt in Hawaii (photos)
Read more: ATLAS observatory atop Hawaii's Mauna Loa volcano watching eruption closely

The alert, issued in conjunction with USGS's Hawaiian Volcano Observatory (HVO), noted that the HVO is set to perform aerial reconnaissance flights as soon as possible "to assess hazards and better describe the eruption," and that "winds may carry volcanic gas and possibly fine ash and Pele's Hair downwind." Pele's hair are thin strands of volcanic glass formed from cooling lava, which can be carried aloft by strong winds and are sharp enough to lacerate skin and eyes.

Mauna Loa takes up more than half of Hawaii's Big Island and rises 13,679 feet (4,169 meters) above the Pacific Ocean, according to USGS (opens in new tab). The volcano is fairly active, having erupted 33 times since its first well-documented eruption in 1843. Its last eruption was in 1984 when it sent a lava flow close to the city of Hilo. After that, Mauna Loa entered its longest dormant period in recorded history (opens in new tab).

Warning signs of an eruption have gradually increased since September, as geologists tracked an uptick in earthquake frequency. This began with five to 10 earthquakes a day in June, and grew to up to around 40 a day in October. 

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Ben Turner
Live Science Staff Writer

Ben Turner is a U.K. based staff writer at Live Science. He covers physics and astronomy, among other topics like weird animals and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.

  • Mergatroid
    I thought the super volcano in Yellowstone was the largest in the world?
    Reply
  • Wolfshadw
    Mergatroid said:
    I thought the super volcano in Yellowstone was the largest in the world?
    Hawaii's Mauna Loa, the world's largest active volcano, is erupting for the first time in nearly 40 years.

    Key word there being "Active". Also. not sure the super volcano at Yellowstone is the largest.

    -Wolf sends
    Reply
  • billslugg
    There were no US satellites in 1957. There was a feverish race between the US and the USSR to be the first to put one up there. Had the US military gotten one up, we would have all known about it.

    Vanguard TV-3 was the first attempt, on Dec 6, 1957 and it got only 3 feet off the pad. The first orbital launch was Explorer-1, Jan 31, 1958.
    Reply
  • Unclear Engineer
    I think the "largest" volcano title is something that media people use for click bait, using whatever definition can be made to fit the volcano they are writing about at the moment.

    In the case of Mauna Loa, I think that it is the biggest in volume when measured from its base to its summit, if you assume that its base is the bottom of the Pacific Ocean and the whole island is the volcano. The tallest is its neighbor, Mauna Kea.

    See https://www.usgs.gov/faqs/how-big-are-hawaiian-volcanoes .

    Other volcanos are higher in altitude at their peaks, have larger caldera, etc.

    See https://en.wikipedia.org/wiki/List_of_volcanoes_by_elevation .

    And the term "active" is also poorly defined and abused by writers looking for superlatives. For instance, "active" sometimes means "actively erupting", sometimes means "is still expected to erupt again in the future" and even "might be able to erupt again some time in the distant future".
    Reply
  • billslugg
    Smithsonian Global Volcanism Program defines "largest" by volume measured from base to top, even if the base is underwater.
    "Active" is defined as having erupted in the last 10,000 years or is showing signs of unrest.
    "Dormant" volcanoes erupted longer ago than 10,000 years but scientists believe they are still connected to a magma chamber.
    "Extinct" volcanoes are no longer connected to a magma chamber.

    https://www.universetoday.com/29662/active-volcano/
    Reply
  • Unclear Engineer
    Yes, those geologists know how to make meaningful definitions. Media types - not so much.
    Reply
  • billslugg
    You got it. It is called "A headline that wrote a check the body of the story could not cash".
    Reply