Alaska's Pavlof Volcano, 590 miles southwest of Anchorage, has quieted down after its strongest eruption of the year, but the Alaska Volcano Observatory (AVO) says low-level tremors continue.
The volcano erupted overnight on Monday into Tuesday, sending ash 28,000 feet into the air and disrupting local flights.
The eruption was the strongest the volcano has emitted in 2013. Scientists first started to see signs of activity on May 16, and they say it's intensified over the past six weeks.
"For some reason we can't explain, it picked up in intensity and vigor," Tina Neal, an observatory geologist, told Reuters.
According to the AVO, as of Thursday, the volcano's activity was still continuing, but at much lower levels than earlier in the week.
"Periods of continuous tremor are likely associated with lava fountaining and minor ash production, but at this level, emission rates are probably very low," the AVO said in its daily volcano update.
But it also noted, "It is possible for conditions to change at any time."