ANCHORAGE, Alaska (AP) — The largest earthquake to ever rock Alaska's North Slope was followed about six hours later by the second largest — an aftershock of the first.
A magnitude 6.4 earthquake shook the ground at 6:58 a.m. Sunday about 343 miles (551 kilometers) northeast of Fairbanks.
The epicenter was north of the Brook Range, the mountains that run west to east from northern Alaska to Yukon Territory.
A magnitude 6.0 aftershock struck at 1:15 p.m.
Alaska's North Slope is the source for most oil extracted and exported from the state.
The University of Alaska Fairbanks' Alaska Earthquake Center says it immediately began to field questions about whether the quake was a result of "induced seismicity."
The center says everything known about the earthquake is consistent with natural activity.