USGS HVO Press Release — Magnitude-4.0 earthquake at summit of Mauna Loa

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The U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.0 earthquakebeneath the Island of Hawai‘i on Tuesday, September 6, 2016, at 4:25 a.m., HST.

According HVO, the earthquake occurred underneath Moku‘āweoweo, Mauna Loa's summit caldera, at a depth of 1.2 km (0.74 mi). A map showing its location is posted on the HVO website at

The USGS "Did you feel it?" Web site ( received only one felt report within an hour of the earthquake. This report described light shaking (Intensity III). At that intensity, damage to buildings or structures is not expected. The lack of felt reports is consistent with the remote location and shallow depth of the earthquake.

The earthquake this morning appears to be isolated. As of 6:30 a.m., HST, no aftershocks have been observed. HVO's deformation monitoring instruments registered the earthquake but show no significant change in deformation rates or patterns that would indicate increased volcanic hazard at this time.

Magnitude-4 or greater earthquakes occurred in the summit of Mauna Loa six to seven months prior to the volcano's two most recent eruptions in 1975 and 1984. However, today's isolated earthquake does not represent a significant departure from the seismic activity rate for the past year, so the Volcano Alert Level for Mauna Loa will remain at Advisory.

According to HVO's Scientist-in-Charge, Christina Neal, the earthquake had no apparent effect on KILAEUA Volcano's ongoing eruptions. The Pacific Tsunami Warning Center determined that no damaging tsunami was generated (

Daily updates about ongoing eruptions, recent images and videos of summit and East Rift Zone volcanic activity, maps, and data about recent earthquakes in Hawaii are posted on the HVO website at

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