Lyn Topinka, USGS
Mount St. Helens had a small eruption in May of 1982.
John Pallister, USGS
An aerial view of Mount St. Helens from Sept. 26, 2004, shows its northern flank and lava dome.
Mount St. Helens sends a huge column of steam and ash skyward, one day after scientists warned an eruption was imminent. The Washington state mountain was the site of a catastrophic surprise eruption in 1980.
Before Friday's mild eruption, Mount St. Helens had lain dormant for 18 years. Experts say the eruption did not pose a threat to public safety. Hear NPR's Craig Windham.