Update 2:15 p.m. Sunday: Another four-plus magnitude aftershock took place along the fault near Minto at 1:58 p.m. The aftershock, which registered as a magnitude of 4.08, occurred closer to the surface than the previous three that registered above 4.0.
The 1:58 p.m. shake took place at a depth of about 6 miles. It could be felt in Fairbanks as a minor shake lasting a couple seconds.
Update 4:30 a.m.: Another earthquake shook Interior Alaska at 4:25 a.m. Sunday, originating from the same general area as a magnitude 5.07 quake at 7:06 p.m. Saturday.
The 4.19 magnitude earthquake was centered 8 miles east of Minto, 38 miles northeast of Fairbanks, at a depth of 12 miles. It was felt strongly as far east as Two Rivers and throughout the Fairbanks and North Pole areas, waking some residents.
A 3.49 magnitude quake centered on the same fault east of Minto shook the area at 12:10 a.m.
State Seismologist Michael West said the quake just after midnight and the following quake at 4:25 a.m. were almost surely aftershocks of the larger 5.1 magnitude quake that hit the interior Saturday evening.
West runs the Alaska Earthquake Center, which tracks movement around the state and has been following the aftershocks along the fault near Minto. He said his office has recorded more than 200 aftershocks since the original quake Saturday night, most of them too small to be felt.
Despite the frequent aftershocks, West said seismologists don't expect another large earthquake from the area.
"At this time there's no evidence to suggest that this is part of a larger sequence or there's something larger to come," West said. "That said, it always remains a slim possibility following an earthquake like this."
Earthquakes in the Minto area are not without precedent, as a fairly active fault exists in the area.
"A lot of the earthquakes that we feel in the Fairbanks area originate in the northern Minto region or Minto Flats somewhere," he said.
The earthquake this weekend seemed to most closely resemble a quake that struck just less than 20 years ago, in 1995, according to West. That earthquake, a magnitude 6.0 struck along the same fault system near Minto and with the same orientation as this weekend's quake, though it was much more energetic.
The energy release of a magnitude 6.0 earthquake is about 20 times greater than that of a 5.1 magnitude earthquake.
West described the events of the weekend as somewhat bittersweet from a scientific standpoint. His office is in the final planning stages of a project that would station a number of additional monitoring instruments in the Minto Flats region this fall to better understand the fault system there — meaning it just missed catching the large quake by a few months.
West said — in light of the weekend's events — his office will try to expedite the placement process and get the devices installed in the next several weeks to measure the series of minor aftershocks that continue to strike the region.
FAIRBANKS - Interior Alaska residents were jolted by a moderate earthquake at 7:06 p.m. Saturday.
Preliminary measurements show a magnitude of 5.07. It was centered about 43 miles northwest of Fairbanks, near Minto, at a depth of 10 miles. The quake was widely felt in the Fairbanks and North Pole areas and as far as Healy and Manley Hot Springs.
Residents said they felt shaking for about 10 seconds.
No reports of damage have been received.
Original reporting was contributed by Julie Stricker and added to by Weston Morrow.