The 1980 eruption of Mount St. Helens, a volcano located in the Pacific Northwest, was one of America’s most catastrophic natural disasters. That day, an 80,000-foot column of ash rose up into the sky, quickly spreading over the horizons of 11 U.S. states. In an exhibition commemorating the 40th anniversary of the eruption, the Portland Art Museum presents depictions of this majestic volcano. From late 19th-century imagery, to basalt and obsidian art created by Native Americans, to contemporary paintings, drawings, and photographs, generations of artists portray an elemental force, usually dormant, suddenly demonic. —E.C.