AVolcanic Ash : Mount St. Helens, Washington

AVolcanic Ash : Mount St. Helens, Washington

"By noon, the City was engulfed in darkness by volcanic ash and communications by home telephone were impossible. It was like an eclipse of the sun that lingered, a blinding blizzard and an electrical storm all in one. Light-sensitive street lights came on automatically, traffic stopped, and a strange quiet fell on our community; and everywhere a talcum-like sandy gray powder kept accumulating. Cars, trucks, buses, and trains, all stopped, and planes were re-routed away from the ash cloud."

"From noon until 6:00 a.m. the following morning, the City was in total darkness. Three types of ash fell alternatively on the City: dark gray sand, medium gray sand, and a light gray cement-like dust. All three grades were gritty and light, difficult to sweep or shovel, especially when dry. To make matters worse, shifting winds blew the ash everywhere, severely impairing visibility and driving in our area. It was exceedingly harmful and abrasive to mechanical and electrical equipment, especially motors of vehicles, aircraft and electronic systems. Unlike snow, however, this "precipitation" was not going to melt!"

"The volcanic ash fall was especially crippling—Yakima received 5-8 cm (2-3 in) of this material in the first 24 hours following the explosion. We estimated that several million tons of volcanic ash was deposited on the entire region."