Volcano Watch: Hawai‘i Five-O! Fifty fountaining episodes at Kīlauea summit

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

Hawai‘i, the 50th state, reached a golden anniversary June 27. Surprise, it’s the 50th fountaining episode of the ongoing episodic eruption in Halemaʻumaʻu Crater at the summit of Kīlauea volcano.

There was no celebratory cake, but the north vent served up a 1,030-foot lava fountain — the tallest since Episode 43 — to the delight of visitors to Hawaiʻi Volcanoes National Park and Kīlauea summit livestream/webcam watchers.

The weather was beautiful and wind cooperated by blowing almost all of the tephra southward into remote parts of the national park, with only a trace dusting of Pele’s hair dropping over the town of Pāhala, 18 miles to the southwest.

The Halemaʻumaʻu eruption powered through the first 50 fountaining episodes in 551 days, averaging about 11 days between eruptions. Its longest pause was just less than 30 days and the shortest was less than 1 day.

Similarly, the duration of the fountaining episodes also shown a wide range, averaging about 15 hours, with the longest lasting just more than 140 hours,, or about 6 days and the shortest 4.5 hours.

The Pu‘u‘ō‘ō eruption currently holds the record for longest fountaining episode at 12 days for its Episode 3, while the Kīlauea Iki eruption has the record for the shortest fountaining episode duration at 1.75 hours.

The double fountains are another feature of this eruption that set it apart from previous episodic fountaining Hawaiian eruptions.

Thirty-two of the 50 fountaining episodes in Halemaʻumaʻu erupted double fountains.

The north vent surprisingly only sat out one episode (Episode 17) while the south vent has taken 19 episodes off throughout the eruption, including the past 7 episodes. While it might seem the south vent is taking it a bit easy, the Maunaulu eruption had the next most double fountains with a grand total of 4 episodes erupting lava fountains from east and west vents.

The south vent made up for its extended rest periods by producing the highest fountains of this eruption at 1,770 feet during Episode 43, the same maximum height recorded in Episode 9 of the Maunaulu eruption — which had 12 total episodes.

This falls short of Kīlauea Iki’s record breaking height of more than 1,900 feet during its Episode 16 — that eruption had 17 total episodes — but clearly tops Pu‘u‘ō‘ō’s highest fountains of about 1,525 feet in its Episode 29; the Pu‘u‘ō‘ō eruption had 47 fountaining episodes before transitioning to continuous effusion of lava flows.

Another fact that might only be of interest to enthusiastic followers of the Halemaʻumaʻu eruption — and perhaps people who like statistics — is that the north vent initiated precursory activity that precedes the onset of fountaining episodes 90% of the time.

Hawaiian Volcano Observatory scientists are still unsure what this means, but find it interesting that one vent has been so dominant in starting eruptive activity.

There have been episodes (47 and 48) with precursory overflows exclusively from the south vent; however, during both of these episodes the south vent politely bowed out and let the north vent fountain.

The north vent also holds the record for the most precursory overflows in the episodes we have counted.

Prior to Episode 34, the north vent produced 114 overflows with none from the south vent. Episode 36 was preceded by the most overflows we have counted at 179, alternating between the north vent and south vent. The longest period of precursory overflows was 6 days preceding Episode 44. The shortest was Episode 17, when the south vent went directly into fountaining with no precursory overflows.

A good story needs to end with a bit of suspense, and this one leaves us all pondering a few questions.

Will we see the south vent fountain again? Can the Kīlauea Iki high fountain record ever be broken?

How much longer will this eruption go on? And, of course, what happens next after the fountaining episodes in Halemaʻumaʻu stop?

If you’ve enjoyed getting caught up with Hawaiʻi Five-O, know that Hawaiian Volcano Observatory scientists are keeping a close watch out for any signs of a follow-up episode titled “Magma P.I.”

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VOLCANO ACTIVITY UPDATES

KĪLAUEA volcano

VOLCANO ALERT LEVEL: Advisory

Kīlauea has erupted episodically since Dec. 23, 2024, within the summit caldera. Episode 50 of summit lava fountaining happened for 7 hours June 27. No unusual activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.

WHAT’S NEXT: Summit inflation since the end of Episode 50 indicates another fountaining episode is possible. Models indicate Episode 51 is most likely to occur between July 8 and 15.

MAUNA LOA volcano

VOLCANO ALERT LEVEL: Normal

Mauna Loa is not erupting. Hawaiian Volcano Observatory reports in its July 2 monthly activity update for the volcano that seismic activity decreased compared with the previous month; a total of 94 earthquakes were detected in Mauna Loa’s summit region during the June reporting period after 170 in May.

Earthquakes were broadly scattered beneath Mokuʻāweoweo, the upper Southwest Rift Zone, and the upper northwest flank.

Global positioning system instruments also showed slight contraction throughout the summit region during the past month. Similar pauses were previously detected during the overall inflationary period that persists since the 2022 eruption, with magma refilling the summit reservoir system.

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

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EARTHQUAKES

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

• MAGNITUDE-3.4 earthquake at 7:06 p.m. June 30 located just west of Pāhala at depth of 19 miles below sea level.
• MAGNITUDE-2.4 earthquake at 9:43 a.m. June 29 located 4 miles south of Leilani Estates.
• MAGNITUDE-3.1 earthquake at 8:34 a.m. June 25 located 7 miles south of Hōnaunau-Nāpōʻopoʻo at a depth of 13 miles below sea level.

Visit the Hawaiian Volcano Observatory 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.