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USGS HVO Information Statement — Magnitude-4.2 earthquake under Kīlauea Volcano’s south flank, Island of Hawai‘i

May 23, 2021

The U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.2 earthquake located beneath Kīlauea Volcano's south flank on Sunday, May 23, at 11:41 a.m., HST. 

The earthquake was centered about 15 km (9 miles) south of Volcano, under the Hilina Pali area of Hawai‘i Volcanoes National Park at a depth of 7.5 km (5 miles). A map showing its location is posted on the HVO website at https://www.usgs.gov/observatories/hawaiian-volcano-observatory/earthquakes. More details are available at the National Earthquake Information Center website at https://earthquake.usgs.gov/earthquakes/eventpage/hv72483217

Weak to light shaking, with maximum Intensity of IV on the Modified Mercalli Intensity Scale, has been reported across the Island of Hawai‘i.  At that intensity, significant damage to buildings or structures is not expected.  The USGS "Did you feel it?" service (http://earthquake.usgs.gov/dyfi/) received over 175 felt reports within the first hour of the earthquake.  

According to HVO Scientist-in-Charge Ken Hon, the earthquake had no apparent effect on Kīlauea or Mauna Loa volcanoes. “We see no detectable changes in activity at the summits or along the rift zones of Kīlauea or Mauna Loa as a result of this earthquake. Aftershocks are possible and could be felt.” HVO continues to monitor Kīlauea and other Hawaiian volcanoes for any changes. 

Kīlauea's south flank has been the site of 40 earthquakes of magnitude-4.0 or greater during the past 20 years. Most are caused by abrupt motion of the volcano's south flank, which moves to the southeast over the oceanic crust. The location, depth, and waveforms recorded as part of today's earthquake are consistent with slip along the steep faults of the pali. A few felt earthquakes preceded this event, including a magnitude-3.6 and magnitude-3.4 earlier in the morning. Aftershocks from this magnitude-4.2 earthquake are likely. 

For information on recent earthquakes in Hawaii and eruption updates, visit the USGS Hawaiian Volcano Observatory website at https://www.usgs.gov/hvo.  

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