The U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.3 earthquake located beneath Mauna Loa’s south flank on Saturday at 11:15 a.m. This earthquake was preceded by a magnitude-3.9 at approximately the same location at 11:02 a.m.
The magnitude-4.3 earthquake‘s epicenter was about 3 miles northwest of Pahala, near Wood Valley, with a depth of approximately 5 miles below sea level.
Weak to light shaking, with maximum Intensity of IV on the Modified Mercalli Intensity Scale, had been reported across the island. The USGS “Did you feel it?” service received over 130 felt reports within the first hour of the earthquake, including one report from Kauai.
According to HVO Scientist-in-Charge Ken Hon, the earthquake had no apparent effect on Mauna Loa or Kilauea volcanoes.
“At this time, we have not observed any changes in activity at Mauna Loa or Kilauea as a result of this earthquake. HVO continues to monitor Kilauea and other Hawaiian volcanoes for any changes,” Hon said.
Both the magnitude-4.3 and magnitude-3.9 earthquakes appear to be slip along vertical faults caused by southeast motion of Mauna Loa’s south flank. Saturday’s earthquakes are significantly shallower and west of the location of the ongoing seismic swarm under the Pahala area that began in August 2019.
HVO said it does not represent a significant departure from the seismic activity observed over the past year and the Volcano Alert Level for Mauna Loa remains at ADVISORY. Other Mauna Loa monitoring data streams show no significant change in deformation rates or patterns that would indicate increased volcanic hazard at this time.
For information on recent earthquakes in Hawaii and eruption updates, visit the USGS Hawaiian Volcano Observatory website at usgs.gov/observatories/hawaiian-volcano-observatory.