01:52 PM PDT on Tuesday, May 30, 2006

NWCN.com and kgw.com Staff

USGS

A plume of steam rises from Mount St. Helens on Memorial Day, 2006.

VANCOUVER, Wash. - A 3.1 earthquake occurred near Mount St. Helens on Monday morning. The quake, at 9:08 a.m., was accompanied by a steam and ash plume. Airline pilots estimated the plume rose to 16,000-20,000 feet.

The National Weather Service issued an ashfall advisory for the area.

Carolyn Driedger with USGS said it looked as though some parts of the new dome and fin have collapsed, though it was not known if the quake caused the collapse or the collapse caused the quake.

Low clouds prevented scientists from getting a good look at the mountain.

Geologists at the U.S. Geological Survey reported a slight increase in the size and frequency of earthquakes at the mountain over the past few weeks but say the increased activity is normal for the mountain's range of activity in the past year.

Dome building in the crater of Mount St. Helens has been taking place since September of 2004 and a large fin has grown, then fractured, and begun to grow again in the past month.