A volcano on an uninhabited island could erupt again after spewing ash into the sky for the first time in 20 years, scientists said.

Scientists plan to study thermal imaging of Augustine Volcano on Thursday for any signs of a magma dome building at its summit.

"It doesn't look like it's ending, even though it's relatively quiet right now," Stephanie Prejean, a seismologist with the U.S. Geological Survey, said Wednesday after the volcano spewed ash about five miles into the sky. "We would not be surprised to see more eruptive activity in the near future."

The ash cloud had given way to a thick plume of steam by the time scientists from the Alaska Volcano Observatory arrived about nine hours after the eruption. Scientists determined most of the ash probably blew northeast and fell into Cook Inlet.

If weather is good and seismic activity low on Thursday, scientists in Homer, about 75 miles northeast of the volcano, may venture near its base to retrieve ash collection buckets.

The shape of the volcano's summit remained largely unchanged, Prejean said. Mud flows streaming down the mountain's east side had been spotted, she said.

The eruption did not disrupt air traffic or cause evacuations in nearby communities, but it prompted authorities to warn pilots to avoid the cloud. Ash can clog jet engines.

The 4,134-foot volcano, which is nearly 200 miles southwest of Anchorage, last erupted in 1986. Ash from a seven-mile-high column drifted over the state's most populous city and forced flights to avoid the skies over Cook Inlet.

If the volcano follows a pattern similar to 1976 and 1986 eruptions, seismic activity would increase before similar or larger explosive events, according to the observatory. However, it's possible that an explosive eruption could occur with little or no warning, the observatory said.