Richard Buckmaster, a geophysicist at the National Earthquake Information Center in Golden, Colo., says the southeast region of the island was hit Saturday by 20 earthquakes with magnitudes of 2.6 or greater.
He says the 5.9 magnitude quake is expected to be upgraded to 6.1.
The quakes are centered southeast of Old Harbor, but there have been no reports that they've been felt.
Ron Fox, a resident of Old Harbor, says he hasn't felt any.
The earthquakes follow two light quakes that struck the same area less than an hour apart Friday.
One of Friday's quakes was felt in Old Harbor.
Buckmaster says the area is seismically active because the Pacific and North American plates intersect along the island and neighboring Aleutian Islands chain.
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