USGS Volcanoes: Notices released in the last day.

Slow eruption of lava continues. Minor seismicity detected over the past day. Slightly elevated surface temperatures were observed in satellite data. Nothing was evident in web camera observations of the volcano.

The current eruption began in July 2021 and, since then, lava flows have filled most of the summit crater and advanced into valleys below. There have been no explosions at Great Sitkin Volcano since an event in May 2021. The volcano is monitored using local seismic and infrasound sensors, satellite data, webcams, and regional infrasound and lightning networks.

The volcano was seismically quiet over the past day. Cloud cover prevented clear satellite views of the volcano. Sulfur dioxide emissions were detected in TROPOMI satellite data.

There is no real-time geophysical monitoring network at Mount Kupreanof. The closest functioning seismometers are approximately 17 miles (27 km) to the east of the volcano as part of the Mount Veniaminof network. Mount Kupreanof is also monitored by satellite data, remote infrasound and lightning networks, and visual observations from pilots and mariners passing by the volcano. 

Minor seismic activity and infrasound were detected at the volcano. Sulfur dioxide emissions drifting to the southwest were evident in satellite imagery. Nothing was observed in partly cloudy satellite views over the past day. Minor steaming was observed in a few clear web camera views from yesterday (5/31); today, web cam views obscured by clouds.

Local seismic and infrasound sensors, web cameras, and a geodetic network are used to monitor Shishaldin Volcano. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lightning data, and satellite images to detect eruptions. 

Monitored CALIFORNIA VOLCANOES
Current Volcano Alert Level: all NORMAL
Current Aviation Color Code: all GREEN

Activity Update: All volcanoes monitored by CalVO show normal background earthquake activity and deformation. Monitored volcanoes include Mount Shasta, Medicine Lake Volcano, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, Ubehebe Craters, and Salton Buttes.

Past Week Observations for May 25 (0000h PDT) to May 31 (2359h PDT):

One earthquake greater than M1 was recorded within the Clear Lake Volcanic Field, with a magnitude of M1.9.

Typical seismicity was recorded at The Geysers geothermal field south of the Clear Lake Volcanic Field; 88 earthquakes greater than M1 were recorded, with the largest having a magnitude of M2.6.

Two earthquakes greater than M1 were recorded in the Sierra Nevada Block, south of Mammoth Mountain and Long Valley, with the largest having a magnitude of M2.3.

Five earthquakes greater than M1 were recorded in the Coso Volcanic Field, with the largest having a magnitude of M2.9.

Six earthquakes greater than M1 were recorded near the Salton Buttes, with the largest having a magnitude of M1.6.

Activity Summary: 

• Episode 48 of the ongoing Halemaʻumaʻu eruption at the summit of Kīlauea ended abruptly at 1:37 p.m. HST on June 1, 2026, after 9 hours of continuous lava fountaining from the north vent. The eruption is currently paused.
• The Halemaʻumaʻu eruption now has the most fountaining episodes ever recorded for an episodic fountaining eruption, edging out the Pu‘u‘ō‘ō eruption which had 47 fountain episodes. Other eruptions have had additional episodes related to changes in vent activity and location, this only applies to episodic fountains.
• Most tephra fell within the closed area of Hawaiʻi Volcanoes National Park, but sparse reticulite up to 1 inch (2 centimeters) in size fell at both the Uēkahuna overlook and on Highway 11 west of Nāmakanipaio campground. Fine ash and Peleʻs hair was reported from Hawaiʻi Volcanoes National Park in communities to the northeast, including Mauna Loa Estates, Ohia Estates, Volcano village, and Royal Hawaiian Estates.

Episode 48 Chronology:

Lava fountaining episode 48 in Halemaʻumaʻu at the summit of Kīlauea began at 4:40 a.m. HST on June 1 and stopped abruptly at 1:37 p.m. HST on June 1, after just under 9 hours of continuous fountaining from the north vent. The last minute was marked by gas jetting at the north vent. The south vent never fountained during this episode, but it periodically spattered and had a few episodes of jetting. The instantaneous effusion rate peaked at about 415 cubic yards (320 cubic meters) per second just before 6:00 a.m. HST, with an average effusion rate of 245 cubic yards (185 cubic meters) per second for the entire fountaining episode. An estimated 7.3 million cubic yards (5.6 million cubic meters) of lava erupted and covered about 40% of the Halemaʻumaʻu crater floor. The Uēkahuna tiltmeter (UWD) recorded about 17.1 microradians of deflationary tilt during episode 48.

Episode 48 lava fountaining began approximately 35 hours after the onset of precursory lava overflows at 5:41 p.m. HST in the evening of May 30. These continued throughout the next day and were amazingly uniform in duration (5-10 minutes) and interval (15-30 minutes).  There were 95 precursory overflows erupted only from the south vent, though spattering was visible at the north vent throughout most of this time. North vent spattering preceded the overflows starting with 2 very small spatter events on the evening of May 27. No additional spatter was visible until the evening of May 28, when the north vent began sporadic spattering that continued until the north vent overflowed at 3:46 a.m. HST June 1. North vent dome fountaining then steadily escalated in vigor and height until it transitioned to episode 48 fountaining at 4:40 a.m. HST June. After the north vent became active, the south vent continued overflowing cyclically, but over the next hour its activity diminished to only spattering as the north vent fountains grew. Meanwhile, the north vent lava fountain grew steadily until reaching a maximum height of around 650 feet (200 meters) by about 5:50 a.m. HST. Over the next several hours the fountain height gradually declined, and it was estimated under 300 feet (90 meters) high about 1 hour before the episode ended at 1:37 p.m. HST on June 1.  

The north vent lava fountain produced significant heat and ash, feeding a plume that reached a maximum height of about 25,000 feet (7,600 meters) above sea level based on radar data reported by the National Weather Service and Washington Volcanic Ash Advisory Center. At first, lower-level trade winds from the northeast pushed most tephra from the lava fountaining to the southwest of Halemaʻumaʻu.  As the plume cloud grew, winds from the south at higher elevations between 10,000 feet and 20,000 began moving the plume northward. This allowed tephra to spread out and fall at a number of locations around the rim of Kaluapele (Kīlauea caldera). At 5:31 a.m. HST, the National Weather Service issued an ashfall advisory for the southeast and northeast of Island of Hawaiʻi, including Hawaiʻi Volcanoes National Park. Sparse pumice up to 1-2 inches (2-5 centimeters) in size fell at the Uēkahuna overlook and Nāmakanipaio campground along with Highway 11 west to the 34-mile marker. Fine ash and Peleʻs hair were deposited around Kīlauea Visitor Center and outside Hawaiʻi Volcanoes National Park in communities to the northeast, including Mauna Loa Estates, Ohia Estates, and Volcano village as well as to the west of the caldera between the 34- and 36-mile markers.  Very sparse, fine ash was reported as far as Mountain View.  A commercial pilot reported a sulfur and ash cloud off of Laupāhoehoe that resulted in cancellations and diversions of several morning flights to Hilo.

A small swarm of earthquakes along the southwest side of Halemaʻumaʻu crater just preceded the end of episode 48. The earthquakes began around 12:15 and have continued sporadically for several hours following the end of episode 48.  There were approximately 15 locatable earthquakes varying from just under magnitude 1 to magnitude 2.2.  Three of the earthquakes were magnitude 2 or greater, 8 were between magnitude 1 and 2 and 4 were less than magnitude 1.  The earthquakes had no visible impact on the eruption or Halemaʻumaʻu crater.

Published Notices about episode 48: 

The National Weather Service issued an ash advisory for south and east Hawaiʻi.  WWA Summary by Location for 19.41N 155.29W with HIZ052/HIC001/HIZ338 emphasis Ashfall Advisory

Hawaiʻi County Civil Defense Agency released an ALERT notifying residents to prepare for ash and tephra by closing windows and disconnecting catchment systems where possible. Everbridge - Mass Notification

HVO short messages posted to the HVO website and social media as episode 48 progressed: HVO - Observatory Messages | U.S. Geological Survey

VAN/VONA end of episode 48: USGS Volcano Notice - DOI-USGS-HVO-2026-06-01T17:22:33+00:00

Kilauea Daily update for June 1 during episode 48: USGS Volcano Notice - DOI-USGS-HVO-2026-06-01T18:32:06+00:00

Status Report with details of ash and tephra fall: USGS Volcano Notice - DOI-USGS-HVO-2026-06-01T16:10:56+00:00

Volcano Activity Notice issued when fountains reached their maximum: USGS Volcano Notice - DOI-USGS-HVO-2026-06-01T16:10:56+00:00

Volcano Activity Notice when episode 48 fountains began: USGS Volcano Notice - DOI-USGS-HVO-2026-05-31T03:58:43+00:00

Hazard Analysis: 

• Volcanic Gas: Water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂) are continuously released during an eruption. SO₂ reacts in the atmosphere to create the visible haze known as vog (volcanic smog) downwind, which may cause respiratory and other problems. Further information on vog can be found at https://vog.ivhhn.org/
• Tephra: Small glassy volcanic fragments—volcanic ash, pumice, scoria, Pele’s hair and reticulite—are created by the lava fountains. A combination of fountaining dynamics and wind conditions determines where tephra fall may occur for any given eruption episode. Larger particles fall near the vents while light particles may be wafted greater distances. These particles may be remobilized during windy conditions following recent eruptive episodes. Residents and visitors should minimize exposure to these fragments, which can cause skin, eye, and respiratory irritation. More information and guidance on tephra fall hazards is available at the links below:
  • https://seagrant.soest.hawaii.edu/resource-and-guidance-for-volcanic-tephra-fall/  
  • https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf
• Lava flows: Generally advance slowly downslope, and during this eruption flows have been confined to Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera. 
• Other: Significant hazards exist around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes. Close to the vents, the tephra material on the crater rim is prone to cracking, slumping, and small landslides that sometimes expose hot and molten material within. This underscores the extremely hazardous nature of Kīlauea's caldera rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since late 2007.

Lava fountaining for episode 48 of the ongoing Halemaʻumaʻu eruption at the summit of Kīlauea ended at 1:37 p.m. HST on June 1 after 9 hours of continuous lava fountain from the north vent. Due to reduced ground and aviation hazards, the USGS is dropping the Volcano Alert Level from WATCH to ADVISORY and the Aviation Color Code from ORANGE to YELLOW. Additional details on this eruptive episode will be provided in the next official report.

Alert level and aviation color code definitions: https://www.usgs.gov/programs/VHP/alert-level-system. Another VAN will be published when lava fountaining for episode 48 reaches its peak height.

• All eruptive vents and lava flows are confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park. Tephra fall from volcanic ash clouds is greatest within 3 miles (5 km) of the vents, lighter ash and Pele's Hair may stay suspended for large distances from the vents.
• Support science and community awareness by reporting tephra fall: https://hawaiiash.science/report_form 
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: https://youtube.com/@usgs/streams 
• KPcam and MK2cam provide views of the plume height for aviation purposes
• Additional short updates as the episode progresses will be posted here: https://www.usgs.gov/observatories/hvo/observatory-messages 
• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 

Most lava fountaining episodes since December 23, 2024, have continued for a day or less.