USGS: “This photo of the ongoing eruption in the Kīlauea rift zone in the Middle East was taken during a Hawaiian Volcano Observatory helicopter flyover on the morning of September 17, 2024. Geologists observed fountains from eruption fissures and active lava flows on the floor of Nāpau Crater, just below (northeast) the September 15 eruption fissure. This south-facing view shows current activity from the north side of Nāpau Crater.” (USGS photo by A. Ellis)

(BIVN) – Active fissures are producing lava flows that cover the floor of Nāpau Crater Tuesday morning as the new eruption in Kīlauea volcano’s central east rift zone entered a third phase of activity.

The USGS volcano alert level for Kīlauea remains at “WATCH” with the aviation color code ORANGE.

In a morning update, the USGS Hawaiian Volcano Observatory said the new eruption, which began late Sunday night, had entered a third, more intense phase of activity.

From the USGS HVO update released Tuesday morning:

Activity summary: Kīlauea volcano is erupting in Hawai’i Volcanoes National Park from a new fissure that opened in Nāpau Crater between 4:00 and 5:00 a.m. HST this morning. Current eruptive activity began with a small eruption that occurred on the evening of September 15 from a fissure just west of Nāpau Crater and lasted for a few hours. A second phase of the eruption began yesterday evening at approximately 6:00 p.m. Activity decreased overnight until a third phase of the eruption began at approximately 4:00 a.m. this morning. The eruption is occurring in a cordoned off and remote area of ​​Hawaiʻi Volcanoes National Park. There is no immediate threat to life or infrastructure. The cordoned off Chain of Craters Road is well downslope and downwind of the eruption. Residents of nearby residential areas may experience volcanic gas emissions associated with this activity, which may increase or decrease over the next few hours and days. The Volcano Alert Level/Aircraft Color Code remains at WATCH/ORANGE. No changes have been observed in the lower East Rift Zone or Southwest Rift Zone.

USGS: “Geologists from the USGS Hawaiian Volcano Observatory collected a sample from the Kīlauea eruption in the Middle East Rift Zone in Nāpau Crater, within a restricted area of ​​Hawaii Volcanoes National Park. Geologists poured molten lava into a metal bucket and quickly quenched it with water. The rapid quenching is necessary to preserve the geochemistry of the fresh sample and prevent changes that would result from the formation of crystals during slow cooling. The samples are taken to the laboratory for analysis and provide scientists with information about conditions in the magma chamber and the path of the magma to the surface.” (USGS video by A. Ellis)

Summit observations: About 17 earthquakes have been recorded beneath the summit region of Kīlauea over the past 24 hours, at depths of 1–3 km (0.6–1.9 mi) below the Earth’s surface and with magnitudes of M2 or less. Summit inclinometers (UWE, SDH, and IKI, located northwest, southwest, and east of the summit, respectively) recorded deflationary tilt throughout the day yesterday, with UWE recording a tilt of about 10 microradians over the past 24 hours. This pattern is consistent with magma leaving the summit storage chambers and entering the Middle East rift zone. The most recent measurement of the SO2 emission rate at the summit was 75 tons per day on August 20, 2024.

Observations in the Rift Zone: This morning, several lava fountains approximately 10 meters high created lava flows on the floor of Nāpau Crater. This fissure system opened between 4:00 and 5:00 a.m. HST this morning, as detected by thermal data from the NOAA GOES satellite and the USGS Hawaiian Volcano Observatory (HVO) infrasound, seismic, and camera instruments. Currently, the fissure system at Nāpau is approximately 0.5 km long and runs east-west across the northern crater floor. The fissure appears to have opened just west of Nāpau early this morning and spread eastward as the eruption progressed. As of 8:30 a.m., approximately 25-30% of the floor of Nāpau Crater was covered with lava confined to the crater.

USGS: “This photo of the ongoing eruption in the Kīlauea rift zone in the Middle East was taken during a Hawaiian Volcano Observatory helicopter flyover on the morning of September 17, 2024. Geologists observed fountains from eruption fissures and active lava flows bisecting the floor of Nāpau Crater, just below (northeast) the September 15 eruption fissure. This west-facing view shows the current activity from the east side of the crater.” (USGS photo by A. Ellis)

This eruption sequence was preceded by intense and localized earthquakes between Maunaulu and Makaopuhi craters and was accompanied by ground deformation patterns suggestive of shallow subsurface crack growth or a dike intrusion (a near-vertical crack filled with magma). It began at approximately 6:00 p.m. HST on September 14, 2024. In the following hours, the intensity of earthquake activity decreased, but over the next 24 hours, over 340 shallow earthquakes were recorded near the intrusion, most within 1 to 5 km (0.6 to 3.1 mi) of the surface. Seismic and deformation data showed that magma was moving underground from storage chambers at the summit into the area between Maunaulu and Makaopuhi craters.

The initial phase of the eruption began at about 9:00 p.m. HST on September 15 and lasted until about 10:00 p.m. Heavy rains obscured visibility in the area, but USGS HVO infrasound instruments and seismometers detected a signal typical of escaping gas or steam in the Middle East Rift Zone, and USGS HVO issued a VAN/VONA and raised the alert level to Watch/Orange. A helicopter flyover on the morning of September 16 identified several new but inactive fissure segments totaling 480 meters (yards) in length with small lava cushions up to 90 meters (yards) from the fissures. Measurements of sulfur dioxide emission rates along the Chain of Craters Road downwind of the eruption site on the day of September 16 indicated that the inactive fissure system was emitting about 300 tons per day.

The second phase of the eruption began on September 16 between 6:00 and 7:00 p.m. HST. This eruptive pulse began without any associated geophysical signals. No changes in seismicity, infrasound, or tilt were observed. It was detected by thermal imagery from the NOAA GOES satellite and HVO webcam images. Eruptive activity gradually decreased throughout the night and ended in the early hours of September 17 before the onset of the more violent third phase, which began between 4:00 and 5:00 a.m.

The USGS webcam shows the violent start of the third phase of the eruption early Tuesday morning.

All activity is currently confined to the Middle East rift zone between Makaopuhi Crater and Puʻuʻōʻō. There is no evidence of further downward drift in the MERZ or LERZ.

Analysis: The ongoing MERZ eruption in the Nāpau Crater region is the first in this area since the multi-day Napau fissure eruption in 1997. The eruption is currently in its third phase of vent opening and lava production. Multi-day fissure eruptions are not uncommon and it is currently difficult to say how long eruptive activity will continue. Currently, summit subsidence recorded by the Uēkahuna (UWE) and Sandhill (SDH) inclinometers indicate a constant transfer of magma from the summit to the eruption site. As long as magma is entering the MERZ, eruptive activity is likely to continue.

The Chain of Craters Road in Hawaiʻi Volcanoes National Park is closed to all visitors due to ongoing eruptive activity. The Escape Road is also closed south of the Nāhuku lava tube.