Volcano Watch: When have lava fountains formed on Kīlauea and what are their hazards?

“Volcano Watch” is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.

Kīlauea is in a unique phase of activity in Halemaʻumaʻu Crater, with 12 episodes of dual lava fountains since Dec. 23, 2024.

Several past eruptions were characterized by similar lava fountaining episodes, including at the start of the Puʻuʻōʻō eruption in 1983, the start of the Maunaulu eruption in 1969 and the 1959 Kīlauea Iki eruption.

Even more recently, Fissure 8 — renamed Ahuʻailāʻau by the Hawaiʻi Board on Geographic Names 4 years ago — of the 2018 lower East Rift Zone eruption exhibited a continuous lava fountain for more than 2 months. However, the lava fountain at Ahuʻailāʻau differed from episodic lava fountains occurring recently at Kīlauea summit.

The continuous Ahuʻailāʻau lava fountains were primarily driven by a pressure gradient as magma moved from storage chambers beneath the summit to erupt out of the low-elevation vent on the flank of the volcano.

Episodic lava fountains are driven by changes in pressurization related to new magma being supplied. As new magma accumulates, the amount of pressure builds.

Eventually, lava erupts and depressurizes the system. As magma rises to the surface, magmatic gas rapidly exsolves as bubbles — just like when you open a bottle of soda or champagne.

This gas is a major driving force of the lava fountaining, and the pieces of lava found around the crater rim are filled with bubbles, resembling a stiff foam.

Many people remember the 1983 to 2018 middle East Rift Zone of eruption of Puʻuʻōʻō for the accessible lava flows on the coastal plain and ocean entries. But the first three years of the Puʻuʻōʻō eruption were characterized by 44 lava fountaining episodes that built a prominent cinder and spatter cone standing 835 feet above the surrounding landscape.

Lava fountaining episodes during this eruption occurred every 3 to 4 weeks and lasted about a day.

The geysers of molten rock, which reached heights of up to 1,500 feet, fed lava flows that traveled downslope. Some of the flows reached the Royal Gardens subdivision and destroyed several houses.

At the start of the 1969 to 1974 Maunaulu eruption, 12 lava fountaining episodes occurred in the upper East Rift Zone.

Each fountaining episode generally lasted several hours, slowly building in height until a maximum height was reached, after which the fountains died within minutes.

Fountains from Maunaulu reached up to 1,770 feet, and fed lava flows that traveled downslope, once going more than 12 miles to eventually enter the ocean.

The short but spectacular Kīlauea Iki eruption occurred in the crater just northeast of Kaluapele, the summit caldera.

There were 17 episodes of lava fountaining that filled in the Kīlauea Iki Crater with 440 feet of lava from Nov. 14 to Dec. 20, 1959. The longest episode was 6 days and Episode 15 included the highest lava fountains yet measured on Kīlauea, reaching staggering heights of 1,900 feet.

These high lava fountains built the prominent Puʻupuaʻi cinder cone, which you can view on Devastation Trail in Hawaiʻi Volcanoes National Park.

Hazards associated with lava fountaining include fallout materials, called tephra; volcanic gas emissions; and lava flows.

Tephra generally accumulates in the area immediately downwind of the vent and can build features such as cinder cones. Changes in wind direction and speeds can result in these particles being wafted greater distances to impact nearby communities.

Like all eruptions, increased volcanic gas emissions associated with lava fountains creates volcanic air pollution, or vog, which affects regions downwind.

When lava fountain events erupt on the flanks, they feed lava flows that travel downslope and destroy everything in their path.

The ongoing eruption happening now at the summit is occurring within Halemaʻumaʻu, with lava flows contained in the caldera.

Trade winds normally transport tephra and gas emissions to the southwest, away from the closest communities, but changes in wind conditions can result in Pele’s hair and vog in areas that include Hawaiʻi Volcanoes National Park and nearby communities.

So far, there have been 12 episodes of lava fountaining in the ongoing summit eruption — the same number as Maunaulu.

Lava fountains haven’t reached “high” fountain heights of more than 1,000 feet.

Continuing inflation suggests the eruption will likely continue, but whether it catches up to Kīlauea Iki or Puʻuʻōʻō in terms of the number of episodes or fountain heights remains to be seen.

Volcano Activity Updates

Kīlauea has been erupting episodically within the summit caldera since Dec. 23, 2024. Its U.S. Geological Survey Volcano Alert Level is at Watch.

The eruption within Halemaʻumaʻu Crater continued during the past week with Episode 12 — which produced active lava fountains, some reaching heights of 600 feet, and flows onto the crater floor, filling about two-thirds — from the morning of March 4 until the morning of March 5.

Kīlauea summit has been inflating since Episode 12 ended, suggesting another eruptive episode is possible.

Sulfur dioxide emission rates are elevated in the summit region during active eruption episodes.

No unusual activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.

Mauna Loa is not erupting. Its U.S. Geological Survey Volcano Alert Level is at Normal.

Four earthquakes were reported felt in the Hawaiian Islands during the past week:

• Magnitude-3.2 earthquake 6 miles south of Hala‘ula at a depth of 12 miles at 3 p.m. March 4.
• Magnitude-3 earthquake 3 miles east-northeast of Honoka‘a at a depth of 0 miles at 4:25 a.m. March 2.
• Magnitude-3.6 earthquake 19 miles south-southwest of Hana, Maui, at a depth of 18 miles at 7:34 p.m. March 1.
• Magnitude-3 earthquake 7 miles south-southeast of Fern Forest at a depth of 4 miles at 7:19 p.m. March 1.

Hawaiian Volcano Observatory continues to closely monitor Kīlauea and Mauna Loa.

Visit the volcano observatory’s website for past “Volcano Watch” articles, Kīlauea and Mauna Loa updates, volcano photos, maps, recent earthquake information, and more. Email questions to askHVO@usgs.gov.