Swarm of Earthquakes Reported Beneath Mauna Loa

A swarm of earthquakes, that began on March 29, 2021, at 2:30 a.m. is occurring beneath the northwest flank of Mauna Loa. Mauna Loa is not erupting and other monitoring data streams currently show no signs of increased activity within the past day.

The U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) has recorded more than 130 earthquakes beneath the northwest side of Mauna Loa’s summit, about 26 miles WNW of Volcano. Most of these earthquakes are occurring in a cluster about one mile wide and three and a half to five miles below the surface.

The largest event in the sequence, so far, was a magnitude-2.7 earthquake, with the bulk of the events being less than magnitude-2. Only one event was reported felt by a resident and was described as weak shaking.

Clustering of shallow earthquakes in this region does not mean an eruption is imminent. HVO has recorded shallow earthquakes in this area for many decades across several eruptive cycles at both Kīlauea and Mauna Loa. These earthquakes may result from changes in the magma storage system and/or may be part of normal re-adjustments of the volcano due to changing stresses within it. Other monitoring data streams for Mauna Loa and Kīlauea, including ground deformation, gas, and imagery, show no significant changes in activity.

HVO continues to closely monitor geologic changes, seismicity, deformation, and gas emissions at Mauna Loa and Kīlauea volcanoes. HVO will issue additional messages and alert level changes as warranted by changing activity.