It was the busy summer season in Yellowstone National Park, a beautiful moonlit night with 18,000 people in the park’s campgrounds and hotels and thousands more in surrounding towns and recreation areas. At 23 minutes before midnight, a talent contest was wrapping up at the Old Faithful recreation hall. A beauty queen had just been crowned. As she walked down the aisle to the applause of several hundred people, the log building creaked loudly and began to shake. Within seconds, the earthquake sent people scurrying for the exits. A park ranger dropped the hand of his date—a waitress from Old Faithful Inn—and rushed to open the doors so no one would be trampled. Nearby, frightened guests fled Old Faithful Inn, where a waterline broke and an old stone chimney soon would collapse into a dining room, thankfully closed at that late hour. Out in the darkness, in geyser basins along Yellowstone’s Firehole River, the Earth began belching larger-than-usual volumes of hot water. About 160 geysers erupted, some for the first time, others after decades-long dormant periods. Sapphire Pool, once a gentle spring, became a violent geyser, hurling mineral deposits around Biscuit Basin. Clepsydra, Fountain, and some other geysers in Lower Geyser Basin began erupting more often than usual. Old Faithful’s eruptions became less frequent, although some observers thought it spouted with unusual vigor earlier that evening. Hundreds of hot springs became muddy. Fountain Paint Pot spewed mud violently, spattering tourist walkways. Rocks and landslides tumbled into park highways in several places, blocking roads between Old Faithful and Mammoth and closing the route to the park’s west entrance at West Yellowstone, Montana. Within an hour, thousands of vehicles streamed out of Yellowstone on roads that remained open—a serpentine parade of headlights fleeing the strongest earthquake yet recorded in the Rocky Mountains and the Intermountain West. The panic and damage in Yellowstone were minimal compared with the unimaginable horror that would overtake a popular Montana recreation area just outside the park’s northwest boundary.
Mineral deposits, occurrences, and associated altered rocks in Southwest Seward Peninsula, western Alaska