USGS HVO Information Statement — Magnitude-4.1 earthquake east of Pāhala

Release Date: AUGUST 18, 2021 The U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.1 earthquake located east of Pāhala on Wednesday, August 18, at 2:02 a.m., HST. The earthquake was centered about 9 km (5 miles) east of Pāhala, at a depth of 33 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/hv72652937/. Weak to light shaking, with maximum Intensity of III 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 25 felt reports within the first half-hour of the earthquake. According to HVO Scientist-in-Charge, Ken Hon, the earthquake had no observable impact on Mauna Loa and Kīlauea volcanoes. “This earthquake is part of the ongoing seismic swarm under the Pāhala area, which started in August 2019. Please be aware that aftershocks are possible and may be felt. HVO continues to monitor Hawaiian volcanoes for any changes. The Alert Levels/Color Codes remain at ADVISORY/YELLOW for Kīlauea and Mauna Loa at this time.” Earthquakes in this swarm occur beneath Kīlauea's lower Southwest Rift Zone, beneath the town of Pāhala and in an area extending about 10 km (6 miles) offshore which occur mostly at depths of 25–40 km (15–25 miles). 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/.