Thursday is a day for the history buffs. The day marks the 40th anniversary of one of the worst natural disasters in U.S. history, when Mount St. Helens, located in southern Washington state near the Oregon border, erupted. To this day, it is still the biggest volcanic eruption in U.S. history, and its effects are still being felt to the surrounding environment four decades later.

The eruption of Mount St. Helens in Washington State on May 18, 1980, was so powerful it turned day into night as ash eclipsed sunshine. The calamity killed 57 people and thousands of animals in the pyroclastic fire.

FILE - In this May 18, 1980, file photo, Mount St. Helens sends a plume of ash, smoke and debris skyward as it erupts. May 18, 2020, is the 40th anniversary of the eruption that killed more than 50 people and blasted more than 1,300 feet off the mountain's peak. (AP Photo/Jack Smith, File)COUGAR, Wash. The coronavirus outbreak disrupted what had been big plans to mark the 40th anniversary of the eruption of Mount St. Helens in Washington state. And Mount St. Helens may not be done yet. The first of a series of small explosions on Oct. 1 shot volcanic ash and gases into the air.