Hawaii’s Mauna Loa, the world’s largest active volcano, erupted last month for the first time since 1984.

The volcano began spewing fountains of glowing rock and ash and spilling lava on Nov. 27. Though it’s been a long time since Mauna Loa last erupted, the U.S. Geological Survey (USGS) said the volcano averages an eruption once every five years throughout its documented history.

According to the USGS, Mauna Loa has erupted 34 times since 1843! The last eruption was 38 years ago, and the one before that was 10 years prior in 1974—meaning the volcano used to ERUPT much more frequently. Before the eruption last month, it was the longest known quiet spell for Mauna Loa, which stands 13,679 feet above sea level.

Heat Wave Facts

• • Mauna Loa is the world’s largest active volcano.
  
  • It last erupted in 1984.
  
  • Feet above sea level: 13,679
  
  • Number of eruptions recorded since 1843: 34

   

Nearby, also on Hawaii’s Big Island, another volcano is erupting simultaneously. Kilauea, which is smaller and more active than Mauna Loa, last erupted in 2018. The two volcanoes erupted simultaneously in 1984 as well.

Government officials said there was no immediate threat to nearby towns, but they will closely monitor the volcanoes’ activities, effects on air quality, and ash that accumulates in surrounding areas. Another concern are the glass fibers that form when hot lava rapidly cools in the air, forming long strands that look like hair. These fibers can be dangerous for people with respiratory problems.

As of press time, the lava has already stopped flowing from three of its four fissures. Eventually the last one will stop flowing, too. But people have sometimes tried to stop Mauna Loa’s eruptions!

In 1935, Gen. George Patton sent bombers to tame the volcano. The bombs were ineffective—and ended up blowing up in the lava or bouncing off nearby rocks. During an eruption in 1881, Hawaii’s governor recommended making appeals to a higher power. A nearby resident made offerings to Pele, the Hawaiian goddess of fire and volcanoes, hoping that she would stop the lava flow and spare nearby property.