ANCHORAGE, Alaska - Mount Redoubt showed increased unrest Sunday as the volcano continued to rumble and grumble and produced a substantial ash and steam plume.

On Sunday, scientists said there was a marked increase of seismicity at the volcano about 161 kilometres southwest of Anchorage.

"It is a bit dynamic right now," said Stephanie Prejean, a geophysicist with the U.S. Geological Survey at the Alaska Volcano Observatory.

Prejean said the day began with more continuous ash emissions. In the afternoon, there was an ash and steam plume that went to 5,500 metres.

The volcano has been in what is called a dome-building phase as it grows a lava dome in its crater.

The dome has grown considerably in recent weeks, observatory scientists said. A tongue of lava now has advanced about 600 metres down the Drift Glacier Gorge.

The volcano had its last major explosion on April 4. Since then, the dome has been growing. It first erupted on March 22. That was followed by numerous large explosions, some sending ash plumes more than 15,000 metres into the air.