4.2 Earthquake Latest in a Series of Swarms from Kilauea’s Southwest Flank

Earthquake 8-1-2020

The Big Island of Hawaii experienced another 4.2 earthquake originating from the Southwest flank of Kilauea volcano near the town of Pahala in the Ka’u district. This earthquake is the latest in a series of mostly small earthquakes that have swarmed the area for the past two years or so.

Is a volcano eruption imminent at that location on the island? HVO scientists assure us that is not the case. But do they know for sure?

Here is the press release sent out after this morning’s 4.2 earthquake:


Magnitude-4.2 earthquake northeast of Pāhala, Island of Hawai‘i

The U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.2 earthquake located on the south part of the Island of Hawai‘i on Monday, August 1, at 10:03 a.m., HST.

The earthquake was centered about 8 km (5 miles) northeast of Pāhala, at a depth of 32 km (20 miles). A map showing its location is posted on the HVO website at http://volcanoes.usgs.gov/hvo/earthquakes/. More details are available at the National Earthquake Information Center website at https://earthquake.usgs.gov/earthquakes/eventpage/hv72070977/.

Light shaking, with maximum Intensity of IV on the Modified Mercalli Intensity Scale, has been reported across parts of 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 150 felt reports within the first hour of the earthquake.

According to HVO geophysicist, Jefferson Chang, the earthquake had no apparent effect on Kīlauea or Mauna Loa volcanoes. “This earthquake appears to be part of the seismic swarm under the Pāhala area, which has been going on for over a year. Out of over ten thousand earthquakes that were detected in the area, a few have been large enough to be felt. We see no detectable changes in activity at the summits or along the rift zones of Mauna Loa or Kīlauea as a result of these earthquakes.” HVO continues to monitor Hawaiian volcanoes for any changes.

Earthquakes beneath Kīlauea’s lower Southwest Rift Zone are produced mostly at depths of 25–40 km (15–25 mi), beneath the town of Pāhala and extending about 10 km (6 mi) offshore. Earthquakes in this region have been observed at least as far back as the 1960s and are posited to be related to deep magma pathways under the island.

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


Melvin Ah Ching is a photographer, consultant, blogger, desktop publisher, and computer enthusiast living and working in Hawaii. The Hawaii Files have been online since 2006.