A shallow underground magma intrusion beneath the Halemaʻumaʻu crater at Kīlauea’s summit triggered nearly 100 earthquakes between September 30 and October 1, 2026. This sudden seismic surge prompted Hawaii Volcanoes National Park officials to temporarily close nearby visitor areas as scientists monitored rapid ground deformation and ongoing volcanic activity.
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Verify & Continue ReadingScientists at the U.S. Geological Survey (USGS) Hawaiian Volcano Observatory (HVO) detected elevated seismic activity and rapid ground deformation beginning at 2:00 p.m. HST on September 30. The data signaled that high system pressurization forced magma into new underground paths beneath the summit caldera, a phenomenon that occurred concurrently with ongoing surface eruptions from the north and south vents.
Seismic Swarms and Ground Deformation
Seismic monitors recorded more than 30 events in an initial six-hour swarm about 1 mile below active vents within Halemaʻumaʻu. Around 8:00 p.m. HST, seismic activity migrated northeast of the active vents, producing over 50 additional earthquakes near an area where satellite imagery had detected ground changes earlier in the month.
The largest event of the sequence, a magnitude 3.4 earthquake, struck at 9:52 p.m. HST at a depth of nearly 1 mile beneath the surface, prompting roughly 30 felt reports across the island. Simultaneously, summit tiltmeters recorded extremely rapid changes consistent with east-west crack growth. The Uēkahuna tiltmeter (UWD) registered approximately 38.5 to 40 microradians of inflation before activity subsided around 3:00 a.m. to 4:00 a.m. HST on October 1.
Current Volcano Status and Safety Warnings
Following the intrusion, USGS kept Kīlauea’s Volcano Alert Level at WATCH and the aviation color code at ORANGE. Monitoring overflights on the morning of October 1 revealed no new ground cracks or anomalously hot zones outside the already fractured caldera floor. However, scientists warn that conditions can change rapidly.
The summit remains at a high level of pressurization, keeping conditions favorable for another lava-fountaining episode or the opening of new vents with little warning. Hawaiʻi Volcanoes National Park continues to restrict access to high-risk zones around the crater rim due to persistent hazards, including volcanic gases, rockfalls, and unstable ground cracks.
Frequently Asked Questions About Kīlauea’s Recent Activity
What triggered the earthquake swarm at Kīlauea’s summit?
The earthquake swarm was triggered by a shallow underground magma intrusion that forced its way through new rock paths beneath the Halemaʻumaʻu crater, causing rapid ground deformation and east-west crack growth.
How many earthquakes were recorded during the event?
USGS recorded a total of 98 shallow earthquakes across the Kīlauea summit region over the 24-hour period, with the largest event registering at a magnitude of 3.4.
Did the magma intrusion cause any new surface eruptions?
No. While existing north and south vents continued to exhibit strong glows, flames, and intermittent overflows, monitoring data and webcam imagery confirmed that no magma erupted in new geographic locations.
What is Kīlauea’s current alert level?
The USGS Hawaiian Volcano Observatory maintains Kīlauea’s Volcano Alert Level at WATCH and the aviation color code at ORANGE due to heightened summit pressurization and ongoing eruptive unrest.
Are nearby areas closed to the public?
Yes. Out of an abundance of caution, Hawaiʻi Volcanoes National Park officials temporarily closed specific visitor areas and trails near the caldera rim, such as portions of the Keanakākoʻi area, due to hazards from ground cracking, rockfalls, and volcanic gas emissions.
