Quake swarms recur near Kilauea summit
An unusual flurry of more than 60 small, shallow quakes at Kilauea volcano Wednesday is no cause for alarm, U.S. geologists say.
"We’ve seen these earthquake swarms before," said Janet Babb, spokeswoman for the U.S. Geological Survey’s Hawaiian Volcano Observatory, noting their occurrence four times in the last couple of decades in the Kaoiki Pali near the boundary between Mauna Loa and Kilauea.
The temblors ranged between one and three miles deep along a fault about three miles north-northwest of Kilauea volcano’s summit. They began at about 1:17 a.m. Wednesday, had slowed by midmorning, but continued as of 4 p.m.
The largest was a magnitude 3.2 at 6:55 a.m. Of the 60 or so quakes, only 14 were greater than magnitude 2.
As history shows, the flurry of seismic activity in this area, near Namakanipaio in Hawai‘i Volcanoes National Park, does not necessarily precede a large earthquake.
"Seismic swarms in the Kaoiki area have sometimes heralded changes in Kilauea’s ongoing east rift zone eruption, but as of this writing, HVO monitoring networks have not detected any apparent changes in Kilauea’s summit or east rift zone eruptions or on Mauna Loa resulting from today’s swarm," the USGS said in a news release.
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Babb said the swarm could be related to the magma supply to the Kilauea summit reservoir, also known as the magma chamber, but that monitoring network instruments such as tiltmeters and global positioning systems do not bear that out.
Few Hawaii island residents reported on the USGS "Did You Feel It? website that they felt a quake.
The USGS received three responses to the 9:08 a.m. 2.2-magnitude temblor. Twelve responded to the 2.3-magnitude quake at 8:07 a.m. And seven reported feeling the 6:55 a.m. 3.2-magnitude earthquake.
Babb said she personally felt the 3.2-magnitude quake and heard a light fixture rattle.
She awoke to the rattling of the fixture during an earlier quake, but said she didn’t feel it.
The previous earthquake swarms along the Kaoiki seismic zone in 1990, 1993, 1997 and February to March 2006 lasted from one day to several weeks.
The quakes rarely exceeded magnitude 4.
The area has had episodes of seismic activity since the November 1983 magnitude-6.6 Kaoiki earthquake.