USGS Volcano Notice - DOI-USGS-HVO-2023-10-20T11:01:41-07:00

Activity Summary: Kīlauea volcano is not erupting. The unrest to the south-southwest of Kīlauea's summit is waning following an intrusive event that began in early October. Unrest may continue to wax and wane with changes to the input of magma into the area. The summit of Kīlauea remains at a high level of inflation and eruptive activity is possible in the coming weeks or months. No unusual activity has been noted along Kīlauea’s East Rift Zone or the Southwest Rift Zone.

Summit Observations: Unrest to the south and southwest of the summit area of Kīlauea has decreased further over the past day. Waxing and waning of unrest may still continue.  

Renewed seismicity beneath the south end of Kīlauea caldera extending to the southwest along the trend of December 1974 vents began on October 16. The renewed activity peaked on October 17 and has been decreasing since then, particularly over the past day. Over the past 24 hours, only 4 earthquakes were recorded in Kīlauea summit region, down from approximately 20 during the previous day. Most of the earthquakes related to the unrest are at depths of around 1–3 km (0.6–2 mi) below the surface.

The Uēkahuna summit tiltmeter located north of the caldera recorded showed inflation over the past day. The Sand Hill tiltmeter, located just southwest of the caldera, was generally flat yesterday, but has shown inflation since about 10 pm last night. GPS units within the south end of the caldera and further south and west have shown little uplift of this region since October 11, when seismicity dropped abruptly. Overall, inflation at the summit of Kīlauea remains high and has surpassed the level seen just before the most recent eruption on September 10th. However, the current rate of inflation in the region has diminished significantly since October 4-6.

Sulfur dioxide (SO₂) emission rates remain low and were measured at a rate of about 100 tonnes per day on October 19.

It is unclear if unrest in Kīlauea summit region will continue and, at this time, it is not possible to say with certainty if activity will lead to an eruption; activity may remain below the ground surface. However, an eruption remains possible, most likely in Kīlauea’s summit region inside of Hawai‘i Volcanoes National Park and away from infrastructure. Similar patterns of earthquake activity and ground deformation occurred to the south of the caldera prior to the September and June 2023 eruptions in Kīlauea summit caldera (in Halemaʻumaʻu crater and on the downdropped block). Volcanic gas emissions pose the greatest hazard to areas downwind of Kīlauea’s summit.

There is currently no sign of an imminent eruption and increasing inflation and earthquake activity (heightened unrest) are expected to precede an eruption. During periods of heightened unrest prior to recent eruptions at Kīlauea summit, signs of imminent eruption did not appear until 1-2 hours before lava reached the surface. The summit of Kīlauea remains at a high level of inflation and eruptive activity is possible in the coming weeks or months. HVO scientists will continue to monitor Kīlauea volcano closely and will issue additional messages as warranted by changing activity.

Rift Zone Observations: No unusual activity has been noted along the East Rift Zone or Southwest Rift Zone; steady rates of ground deformation and seismicity continue along both. Measurements from continuous gas monitoring stations downwind of Puʻuʻōʻō in the middle East Rift Zone have been below detection limits for SO₂, indicating that SO₂ emissions from Puʻuʻōʻō are negligible. 

Hazard Analysis: Levels of volcanic gas (sulfur dioxide and carbon dioxide) can remain locally hazardous even though Kīlauea is no longer erupting. Sulfur dioxide (SO₂) gas emissions have greatly decreased; however, local concentrations of sulfur dioxide (SO₂) or hydrogen sulfide (H₂S) may persist in downwind areas, and residents may notice odors of these gases occasionally. Significant hazards also remain around Halemaʻumaʻu from crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public. For discussion of Kīlauea hazards, please see: https://www.usgs.gov/observatories/hawaiian-volcano-observatory/hazards.

The Hawaiian Volcano Observatory (HVO) continues to closely monitor Kīlauea volcano.

Next Notice: HVO will issue daily Kīlauea updates. Additional messages will be issued as needed.