More than 40 earthquakes occurred in an area below Mauna Loa on Thursday, but the volcano is NOT erupting.
The U.S. Geological Survey’s Hawaiian Volcano Observatory reported that the small swarm of shallow seismicity began at 1 a.m. Thursday morning (HST). It occurs below the upper seismic zone of Ka’ōiki, under the southeastern flank of Mauna Loa and northwest of the summit of Kīlauea. Other Mauna Loa control data streams remain stable and show no signs of increased activity.
OBSERVATIONS
On March 18, 2021, (HVO) recorded more than 40 earthquakes beneath the upper seismic zone of Ka’ōiki, about 13 kilometers NW of the volcano. These earthquakes occur in a cluster about a mile wide and 0.5 to 4 miles below the surface.
The largest event in the sequence, in late Thursday afternoon, was a magnitude 3.5 earthquake. Most of the events have been below magnitude 2 and have not been widely reported by residents. The felt events reported were described as weak shocks, with a maximum intensity of II on the modified Mercalli intensity scale.
The grouping of shallow earthquakes in this region does not mean that an eruption is imminent. HVO has recorded shallow earthquakes in this area for many decades through several eruptive cycles in both Kīlauea and Mauna Loa. These earthquakes show no signs of magmatic impact and are part of the normal readjustments of the volcano due to changes in stress inside. Other Kīlauea and Mauna Loa monitoring data flows, including soil deformation, gas, and images, show no signs of increased activity.
HVO continues to closely monitor geological changes, seismicity, deformation and gas emissions at Kīlauea and Mauna Loa volcanoes. HVO will issue additional messages and alert level changes as guaranteed when changing activity.
For more information on earthquakes in the Kaʻōiki Pali area, see the Volcano Watch article entitled “Why do swarms of earthquakes occur around Kaʻōiki Pali?” published by HVO scientists on March 1, 2012: https://www.usgs.gov/center-news/volcano-watch-why-do-swarms-earthquakes-occur-around-ka-iki-pali .
For information on recent earthquakes in Hawaii and updates on eruptions, visit the USGS Hawaiian Volcano Observatory website at https://www.usgs.gov/observatories/hawaiian-volcano-observatory.
Mauna Loa activity summaries are available by phone: (808) 967-8866. Other summaries of the Hawaiian volcano can also be found by phone: (808) 967-8877.