Mauna Loa: After 38 Years, World's Largest Volcano Erupted; Prompting Ashfall Advisory Over Hawaii

After Mauna Loa, the largest active volcano in the world, had its eruption in Hawaii Volcanoes National Park, an ashfall warning was issued for the Big Island and the nearby waters in Hawaii until 6 AM HST on Monday. This ended the volcano's record prolonged quiet period of 38 years.

Ashfall Advisory

On some areas of the island, ashfall could reach a depth of up to 1/4 inch.

The National Weather Service in Honolulu warned that to prevent breathing in the ash particles, people with respiratory conditions should stay inside, and anyone staying outdoors should cover their nose and mouth with a mask or piece of cloth.

NWS added that there is a possibility of crop and animal damage, as well as minor infrastructure and equipment damage. Additionally, the ashfall will reduce visibility and may necessitate widespread cleanup.

The Hawaii Tourism Authority shared on Twitter Monday morning, that the eruption is not endangering downhill communities. Flights to the island of Hawaii are also unaffected.

According to the Hawaiian Volcano Observatory, lava flows are contained in the Moku'āweoweo summit area and do not pose a threat to communities below. Winds could, however, carry fine ash and volcanic gas downwind.

The observatory pointed out that based on past occurrences, the position and movement of lava flows can change quickly during the early stages of a Mauna Loa eruption. Lava flows will probably be contained within the caldera walls if the eruption continues in Moku'weoweo. Lava flows could move quickly downslope, but only if the eruptive vents spread outside of its walls.

According to the USGS, the Hawaii Volcano Observatory is collaborating with partners in emergency management to track the eruption's nature.

Longest Record Prolonged Quiet Period

According to the observatory, the eruption started on Sunday around 11:30 PM HST in Moku'weoweo, the Mauna Loa summit caldera.

The US Geological Survey reports that Mauna Loa, a volcano that makes up half of Hawaii's island, has erupted 33 times since 1843 when it first made historical records of its eruptions. Since it last erupted in 1984, this protracted period of silence is the longest volcano has ever experienced.

According to the agency, the volcano has been experiencing increased unrest recently. In a late-month update, it mentioned increased earthquake rates and increased seismic activity.

Read also: Mauna Loa - World's Most Active Volcano Eruption Imminent After Over 65 Earthquakes, Officials Recommend Packing Bags 

Months of Unrest

According to the US Geological Survey, the frequency of earthquakes increased from five to ten per day in June 2022 to about ten to twenty per day in July and August. On September 23 and September 29, there were more than 100 earthquakes recorded per day at their peak.

The main area of the park, according to the US National Park Service, has remained open despite Hawaii Volcanoes National Park's decision in October to close the Mauna Loa summit to all backcountry hikers until further notice due to the increased activity, CNN reports.

One of the five volcanoes that make up Hawaii, Mauna Loa, has an elevation of 13,000 ft above sea level. volcanic activity has been detected since September.

Rebecca Williams, a volcanologist and Earth scientist from UK's the University of Hull, told Newsweek that since the middle of September, there has been heightened unrest on Mauna Loa. Both the number of earthquakes and the inflation, or swelling of the ground, had increased. This suggested very deep magma movement beneath the surface. Released types of gases remained unchanged, and there was no discernible ground tilting to indicate that magma was rising to the surface.

Williams added that due to this unrest, the volcano was being closely monitored. However, there was no guarantee of an eruption at the time. Occasionally, these upheavals subside and nothing happens. An eruption does occur occasionally, as in this instance, Newsweek reports.

Related article: Mauna Loa Summit Still Closed After 65 Earthquakes Hit in One Day