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Dozens of earthquakes hit Hawaii as the world's largest volcano erupts
On November 27, Mauna Loa erupted for the first time in nearly 40 years. Located in Hawaii, Mauna Loa is the world's largest active volcano. Volcanoes are openings or vents where lava, small rocks, and steam erupt onto the Earth's surface. Melted rock that comes up from inside the Earth and out of a volcano is lava. The Mauna Loa eruption occurred at the Moku'āweoweo summit caldera. This is a large sunken basin at the summit — or highest point — of the volcano.
Following the eruption, dozens of earthquakes swarmed the region — one of them a magnitude 4.2 quake. Magnitude is a number that characterizes the relative size of an earthquake from 1 to 9.
Remain Vigilant
Officials issued an ashfall advisory for Hawaii's Big Island and asked residents to remain vigilant. So far the eruption's lava flows pose no risk to people living downhill from the eruption, according to Hawaii's Tourism Agency.
Map showing lava flow of Mauna Loa from the years 1843 to 1984.
Image 1. The volcano's last eruption was in 1984, when it sent a lava flow close to the city of Hilo.
"At this time, lava flows are contained within the summit area and are not threatening downslope communities," said officials from the U.S. Geological Survey (USGS). The USGS is a government agency that collects information to help monitor natural hazards such as earthquakes. They warned, however, that the location and advance of lava flows can change rapidly.
The USGS's Hawaiian Volcano Observatory noted that it is set to perform flights to assess the eruption. They warned 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. The glass is sometimes carried into the air by strong winds and is sharp enough to tear skin and eyes.
Monitoring The Volcano
Mauna Loa takes up more than half of Hawaii's Big Island. It rises 13,679 feet (4,169 meters) above the Pacific Ocean, according to the USGS. 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. Periods of time when the volcano is not erupting, but could in the future, are volcanic dormant periods.
Scientists tracked an uptick in earthquake frequency beginning in June with five to 10 earthquakes a day. By September, the warning signs of an eruption increased. The number of earthquakes grew to around 40 a day in October.
