Nearly 100 earthquakes reported at Hawaii’s most active volcano

An earthquake swarm was recorded this week beneath the summit of Kilauea, Hawaii Island’s most active volcano. 

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According to the U.S. Geological Survey, at least 98 small earthquakes have occurred since Wednesday. As of Friday, Katie Mulliken, a geologist with the USGS, told SFGATE that the quakes are not as frequent but are still “trickling in,” with the strongest shake so far measuring at a magnitude 3.5 around 8 a.m. Hawaiian Standard Time on Friday.

The earthquake swarm came in “two distinct clusters,” Mulliken said, starting on Wednesday at around 8 p.m. beneath the volcano’s caldera, which is a large dip in the ground at the top of a volcano that forms when it erupts. Around 30 quakes came in that cluster, and the activity continued for several hours, she said. Dozens more hit on Thursday night, still beneath the caldera, with the strongest quake that night measuring at a magnitude 3.4. 

The earthquakes prompted a partial closure of Hawaii Volcanoes National Park in the Keanakakoi area, which includes Old Crater Rim Drive, the overlooks near Keanakakoi Crater and the Crater Rim Trail to Keanakakoi, according to an alert from the National Park Service. 

Mulliken said the closure comes as an “extra precaution” because conditions can change quickly during a period of volcanic unrest. 

Though the activity mostly died down without an eruption, the ground was deforming with small movements as the shaking occurred. This signifies that magma was moving below the surface, Mulliken said, which geologists are closely monitoring.

According to the USGS, Kilauea has been periodically erupting since Dec. 23, 2024, from the north and south vents. Lava fountaining, which refers to when hot lava shoots into the air from a vent, typically lasts for less than 12 hours and is separated by pauses of at least two weeks, the USGS said. 

Mulliken said there has been a “really consistent pattern of disruptive activity” since then, including 54 episodes of lava fountaining. In the past day, geologists reported Thursday that the vents have continued to glow and contain lava. 

Because the summit is highly pressurized, Mulliken said a lava fountaining event could happen again at some point, or a new vent could open. 

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“When we had that flurry of earthquakes and really rapid ground deformation the night before last night, that was maybe magma trying to find a path to the surface and create a new vent, but it failed to do so,” she said. 

It’s also possible that the activity could migrate out of the summit region and toward one of the rift zones, but geologists determined that there’s no signs of that happening so far. 

“Those are kind of the three possibilities that could come out of this kind of elevated unrest that we’re seeing,” she said. 

Though the earthquake swarms and ground movement may seem alarming, given that it’s been awhile since changes in the ground occurred in the area, Mulliken said the activity is “routine” and that the last similar event at the summit happened in September 2023. 

“Prior to the December 2024 eruption starting, we were seeing similar earthquake swarms and ground deformation as this magma was working its way to the surface, so this behavior is very normal,” she said. “It hasn’t happened in a couple years, which is, you know, why it’s something we’re paying close attention to right now.”

Mulliken said most of the activity is confined to the summit region, a small part of the park, and she advised visitors to check the national park’s website for closure updates. Because of the increased earthquake activity, it’s also important to be aware of any cracks or shaking along the rim of the caldera. 

The activity also comes as a roughly 90-foot natural lava rock formation at Hawaii Volcanoes National Park collapsed on Sunday after a series of powerful storms last month.