Volcano Watch: A new Kilauea eruption

Anew Kilauea eruption began in a remote area of Hawai‘i Volcanoes National Park on Sunday, Sept. 15. This is the first eruption on Kilauea’s middle East Rift Zone (MERZ) since 2018 and it poses no immediate threat to life or infrastructure. The USGS Hawaiian Volcano Observatory is closely monitoring this eruption.

HVO has been in close contact with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency throughout this eruption, which has featured a series of small fissure phases that have each lasted from hours to days. Each phase has increased in volume with the most recent being the largest to date. In total, the fissure system has stretched over 1.8 km (1.1 miles), and lava has covered more than 777,000 square meters (192 acres).

The first phase of the eruption began between 9 and 10 p.m. HST on Sunday evening. Infrasound sensors in HVO’s monitoring network recorded strong signals indicative of gas or steam venting. At the same time, HVO’s seismometers recorded weak but sustained low frequency tremor. Although an eruption could not be confirmed visually Sunday night by webcams or satellite thermal data due to heavy rainfall, the geophysical data indicated that an eruption could be taking place. That night, some residents in nearby communities also reported strong sulfur or burning smells.

The next morning, Monday, Sept. 16, HVO scientists on a helicopter overflight confirmed that a small eruption had occurred on Kilauea’s MERZ between Makaopuhi Crater and Napau Crater. This first fissure eruption was small and covered less than 4 acres. Lava was no longer flowing on the surface as of Monday, but magma was still moving underground as detected by seismometers, tiltmeters and GPS.

Phase two of the eruption began Monday evening around 6 p.m. HST. The onset of this eruptive activity was detected in NOAA GOES satellite thermal imagery and HVO webcam imagery. Interestingly, no changes were detected in other monitoring datasets. Fissures from this phase of the eruption produced lava fountains and flows that gradually decreased through the night. But activity would soon resume.

The third eruptive phase then began between 4 and 5 a.m. HST on Tuesday, Sept. 17. This onset was detected using a combination of infrasound signals, GOES satellite thermal anomaly, and webcam imagery. After sunrise, HVO scientists on a helicopter overflight observed several lava fountains approximately 10 meters (yards) high that were generating lava flows on the floor of Napau Crater. This eruptive phase was more vigorous and longer lived and continued and gradually decreasing levels through Wednesday afternoon.

A fourth eruptive phase began around 3 p.m. HST on Wednesday, Sept. 18, as new fissures opened west of Napau Crater. A monitoring camera deployed by HVO field crews with permission from Hawai‘i Volcanoes National Park recorded “lava falls” cascading down the northwest walls of Napau Crater. Vigorous activity continued into Wednesday evening and lava continued to cascade into Napau Crater as of Thursday morning, Sept. 19.

Shortly after 10 a.m. on Friday, lava flows at the remote crater crusted over late Thursday evening, and while some minor lava fountaining was observed from one end of the volcanic vent Friday morning, that activity ceased by 10 a.m.

This marks the end of the eruption’s fourth phase of fissure activity since it began Sunday night. However, additional phases are still possible and that one body of magma beneath Kilauea summit continues to supply magma to the middle East Rift Zone.

HVO webcam views are available from our website including a new live view of Napau Crater, which can be found here: https://tinyurl.com/bdekkcry. How long will the eruption last? Examining history, numerous MERZ eruptions took place during the 1960s–1970s, most of which lasted less than one day to about two weeks. An eruption near Napau Crater in 1997 lasted two days. The nearby 2011 Kamoamoa eruption lasted five days. Of course, there have also been much longer-lived MERZ eruptions as well. Maunaulu lasted five years and Pu‘u‘o‘o lasted 35 years. Time will tell!

Looking at the bigger picture, this eruption signals a significant and fascinating change in activity at Kilauea. One year ago this week, a Kilauea summit eruption in Halema‘uma‘u was just ending. That eruption, which lasted from September 10-16, 2023, was the fifth in a series of eruptions within Halema‘uma‘u since December 2020. On June 3, the first Kilauea eruption outside the summit caldera since 2018 occurred several miles southwest of Halema‘uma‘u. And now, after a series of seismic swarms and magmatic intrusions beneath the upper East Rift Zone over the past few months, we are witnessing the first MERZ eruption since 2018. It seems that a new era of Kilauea eruptions has begun.

Volcano activity updates

Kilauea’s latest eruption has paused. Kilauea’s USGS Volcano Alert level is WATCH.

On Saturday, Sept. 14, magma intruded into the middle East Rift Zone region of Kilauea. A brief eruption occurred the night of Sept. 15, just west of Napau Crater within Hawai‘i Volcanoes National Park. The eruption resumed late in the day on Sept. 16, and continued through the night, decreasing in vigor until about 4 a.m. HST, Sept. 17, when new vents opened to the east in Napau Crater. At 3:15 p.m. HST on Sept. 17, the Napau Crater vents likely ceased, with eruptive activity shifting west of the crater and generating lava flows over the northwest wall and into Napau Crater. Multi-day fissure eruptions in this area are not unusual and current eruptive activity appears to be linked to supply of magma from the summit. The most recent sulfur dioxide emission rate for the eruption was 10,000 tonnes per day, measured on Sept. 18.

Mauna Loa is not erupting. Its USGS Volcano Alert Level is at NORMAL.

Two earthquakes were reported felt in the Hawaiian Islands during the past week: a M3.1 earthquake 23 km (14 mi) W of Volcano at 8 km (5 mi) depth on September 15 at 1:15 p.m. HST and a M4.3 earthquake 6 km (3 mi) SSW of Volcano at 0 km (0 mi) depth on September 14 at 4:25 p.m. HST.

HVO continues to closely monitor Kilauea and Mauna Loa.

Please visit HVO’s website for past Volcano Watch articles, Kilauea and Mauna Loa updates, volcano photos, maps, recent earthquake information, and more. Email questions to askHVO@usgs.gov.