A magnitude-5.2 quake struck off the coast of Hawai’i’s Big Island on July 5, rocking residents and visitors alike as far away as Kaua’i.
By Megan Sever, Science Writer and Editor (@megansever4)
Citation: Sever, M., 2021, Hawai’i quake likely not volcanic, Temblor, http://doi.org/10.32858/temblor.186
When earthquakes strike the Big Island of Hawai’i, most people assume they’re related to magma movement beneath Kīlauea or Mauna Loa, the twoo active volcanic centers. But occasionally, earthquakes can surprise us. That’s what happened with the magnitude-5.2 quake that struck on July 5 north of the Waipi’o Valley, far from both volcanoes. Shaking was felt all over the island and throughout the Hawaiian Island chain, including 160 miles (about 260 kilometers) away in Honolulu and even in Kaua’i. No tsunami warning was issued, and none occurred. No damage or injuries have been reported.
Although the earthquake’s location may have surprised people like me — I’ve felt quakes on Kīlauea — it didn’t surprise scientists. “This earthquake is related to stress from the weight of the island on the underlying ocean crust and mantle,” said Ken Hon, scientist-in-charge of the Hawaiian Volcano Observatory, in a statement. “These earthquakes are relatively common and not directly related to volcanic processes.” Furthermore, Hon noted, the earthquake had “no observable impact” on Kīlauea or Mauna Loa’s volcanic activity.
More than 1,300 people reported feeling shaking from the earthquake on the U.S. Geological Survey’s Did You Feel It? page. The strongest felt reports, maximum V on the Modified Mercalli Intensity Scale, came from the western side of the Big Island, in the Kohala districts. If you live on or are visiting the Hawaiian Islands and felt the quake (or didn’t), report your experience.
The quake struck about 3 miles (5 kilometers) off the Hāmākua Coast, near the community of Kukuihaele, and was about 17 miles (27 kilometers) deep. The strongest previous quake in this area was a magnitude-4.2 event in 2010. Though this part of the coast is sparsely populated, it is known for its stunning and treacherous hiking trails that attract tourists and islanders alike. The Hawaii Emergency Management Agency recommends finding a clear spot away from trees and power lines if you’re outdoors. Be extra careful hiking in that region, as the cliffsides may have shifted, rocks may be precariously perched, and aftershocks are possible. Although significant damage wouldn’t be expected with the level of shaking experienced, Hawaii County Civil Defense still suggests checking for any damages as a precautionary measure. Underwater earthquakes can cause tsunamis as well. Look up the detailed tsunami evacuation zone maps here, and find specific instructions for your location on the Big Island.
For those living in or visiting any area prone to seismic activity, this quake is a gentle reminder to prepare. Here’s a basic disaster supply list provided by the U.S. government. And don’t forget, if you feel shaking, the USGS recommends that you drop, cover and hold on!
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