Volcano Minute — Earthquakes and ground movement south of Halemaʻumaʻu

Aloha, it's your weekly Volcano Minute, brought to you by the USGS Hawaiian Volcano Observatory. 

Today we’re taking a close look at recent activity beneath the south rim of Halemaʻumaʻu—an area that remains closed to the public and continues to show just how quickly conditions and hazards at Kīlauea’s summit can change. 

Over the past several months, we’ve recorded ongoing shallow earthquakes beneath the south rim, with more than 30 magnitude‑2 and smaller earthquakes occurring just this past week. Most are too small to feel, but together they signal movement only a mile or two beneath the surface. Deeper earthquakes across the summit continue as part of the ongoing eruption. 

This activity follows a small swarm of 15 shallow earthquakes at the end of episode 44 on April 9. They coincided with several inches of uplift along the south rim — though tephra from the eruption makes it hard to see whether cracks or structural changes also occurred. Episode 45 on April 23, by contrast, produced only minor seismicity. 

These patterns echo earlier behavior in 2025, when similar shallow earthquakes preceded the opening of a short‑lived fissure on the south side of Halemaʻumaʻu. They highlight how shallow seismicity can rapidly lead to new eruptive activity. 

This area has also been directly impacted during the ongoing eruption—including in December 2025, when a sudden change in the south vent geometry during episode 38 sent molten tephra southward, destroying the V3 livestreaming camera in seconds. 

All of this reinforces a simple message: that the south rim and surrounding caldera remain hazardous. Rockfalls, ground cracking, and sudden eruptive changes can occur with little warning. Visitors should always follow Hawaiʻi Volcanoes National Park closures, and if you’re in an open area near the rim and feel shaking, move back immediately. 

HVO will continue to monitor Kīlauea closely and provide updates as this dynamic eruption evolves. 

Mahalo for listening, I’m Katie Mulliken and this was your weekly volcano minute brought to you by the USGS Hawaiian Volcano Observatory.