Mauna Loa Update: Layer of Ash from Eruption Expected to Hit Residents

Up to a quarter-inch of ash is forecast to coat the island of Hawaii following the eruption of Mauna Loa.

Mauna Loa, which is the largest active volcano on Earth, started to erupt at 11:30pm Hawaiian local time on November 27, the United States Geological Survey (USGS) announced at 11:45pm.

An Ashfall Advisory has been put into place for all of Hawaii island until 6 a.m. HST Monday, a tweet from Hawaii's Emergency Management Agency said.

"Up to a quarter-inch of ash is expected around and downwind of Mauna Loa. People with breathing difficulties should stay indoors, and cover nose/mouth with cloth or a mask," it said in the tweet.

The USGS statement said that the lava flows are currently contained within the summit area and are not threatening downslope communities. However, they warn that the winds may carry volcanic gas, fine ash, volcanic glass and Pele's hair downwind.

Pele's hair are light fibers of volcanic glass, which can damage lungs, as it is very brittle and sharp.

Volcanic gasses include carbon dioxide (CO2), hydrogen halides (HF, HCl, HBr), hydrogen sulfide (H2S) and sulfur dioxide (SO2). CO2 may flow into low-lying areas and cause asphyxiation in humans and animals if it reaches concentrations of over 13 percent, while SO2 gas is irritating to eyes, skin and the respiratory system, and can form volcanic smog and acid rains. The other gasses are also toxic when inhaled, and can poison local waterways when dissolved, the USGS explains.

Additionally, because of its abrasive structure, volcanic ash can cause breathing problems and damage the lungs if inhaled, as with Pele's hair.

Mauna Loa is located on the island of Hawaii in the Hawaii Volcanoes National Park. The eruption is currently occurring within its summit caldera, named Moku'āweoweo. The volcano, which is between 700,000 and one million years old, has not erupted since 1984. However it began showing higher activity levels in September.

The USGS reports that the number of earthquakes below Mauna Loa's summit increased from 10-20 per day to 40-50 per day in mid-September, causing the Alert level to be increased from Normal to Advisory. Now, the level is at Warning.

It is very difficult to predict the degree of damage this eruption will cause although past evidence shows that Mauna Loa typically erupts lava at a very high rate. According to the USGS, during a 1950 eruption, lava traveled from a vent 10,000 feet above sea level to the ocean in about 3 hours.

"If the eruption remains in Moku'āweoweo, lava flows will most likely be confined within the caldera walls. However, if the eruptive vents migrate outside its walls, lava flows may move rapidly downslope," the USGS said in a statement.

Currently, there is no threat to communities downhill, nor are any flights to the island of Hawaii being impacted.

"The Observatory will continue to monitor and share information with emergency managers as the situation evolves, and update as needed. About half of Mauna Loa eruptions never move beyond the summit area," tweeted the Hawaii Emergency Management Agency.

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