History Channel reminds us of the devastation caused by this volcanic eruption. At 8:32 a.m. PDT on May 18, 1980, Mount St. Helens, a volcanic peak in southwestern Washington, suffers a massive eruption, killing 57 people and devastating some 210 square miles of wilderness. After the city of Pompeii was buried under the might of Mt Vesuvius in 79 ce , an incredible city was discovered under the ash over a thousand years later. For many centuries Pompeii slept beneath its pall of ash, which perfectly preserved the remains.