Swarm of 50 small earthquakes occur beneath Kīlauea summit over three hours

A seismic swarm of approximately 50 small earthquakes was reported over a three hour period, beginning at around 3 p.m. on Tuesday, Sept. 20, 2022, beneath the Kīlauea summit, according to the USGS Hawaiian Volcano Observatory.

HVO scientists say that most earthquakes in this swarm occurred approximately 1 mile beneath the Halemaʻumaʻu Crater. The largest recorded earthquake was a magnitude 2.9, with the majority of the earthquakes being less than magnitude 2, according to the agency.

A status report issued on Tuesday indicates that increased seismicity, ground deformation, and surface lava flows were documented at Kīlauea’s summit on Hawaiʻi Island.

HVO scientists report that there is no indication of activity migrating into either rift zone. 

The increase in earthquake activity beneath the summit was followed by summit inflation beginning around 4:20 p.m., a drop of 23-feet in the lava lake level, and new breakouts of lava on the Halema’uma’u crater floor at 4:30 p.m. 

“This activity likely represented a temporary blockage in the eruption of lava at Halemaʻumaʻu, causing pressurization below the surface. This resulted in the earthquakes and ground inflation,” according to the HVO. “Once the blockage was cleared, eruption of lava resumed with new breakouts occurring on Halemaʻumaʻu crater floor.”

The report indicates that earthquake activity returned to near background levels as of 6 p.m. Tuesday.