The morning began with three sharp earthquakes, the last one reaching roughly magnitude 5. While the ground still shook, superheated groundwater flashed to steam at the fumaroles above the Kaminoyu hot spring resort on Ko-bandai's flank, triggering a phreatic eruption -- an explosion driven not by fresh magma but by trapped water meeting searing rock. What followed was relentless: 15 to 20 blasts per minute, each punching a black column of ash and debris 1,300 meters into the sky, accompanied by thunderclaps that echoed across the basin. The final explosion discharged a lateral cloud that raced mainly northward. Within ten minutes, a pyroclastic flow had swept over the volcano's eastern face. By mid-morning, hot rain was turning the blanket of ash into lahars -- volcanic mudslides that swallowed everything in their path. By 4:00 that afternoon, the ash finally stopped falling. The silence that followed was worse.

Roughly 1.5 cubic kilometers of Ko-bandai's summit had collapsed and flowed northward in a massive debris avalanche. Entire villages vanished beneath the landslide. At least 477 people perished and hundreds more were left injured and homeless. Hundreds of square kilometers of forest and farmland were transformed into a gray wasteland. Rivers found themselves blocked by rubble, their waters pooling behind natural dams of volcanic debris. Where a peak had stood that morning, an enormous horseshoe-shaped crater now gaped open to the north. The mountain's profile, once compared to Fuji, was irreversibly broken.

Geologists Seikei Sekiya and Y. Kikuchi of the Imperial University of Tokyo arrived within days. They spent months mapping the new crater and documenting the devastation, publishing their findings in English in 1890. Their report, 'The Eruption of Bandai-san,' became a foundational text in volcanology and one of the earliest detailed scientific accounts of a volcanic sector collapse. A photograph of the ruined mountain became the first news photograph ever printed by the Yomiuri Shimbun, one of Japan's most prominent newspapers. The disaster also served as the first major test of the fledgling Japanese Red Cross, established just a year earlier, which mobilized quickly to deliver relief to survivors in the Aizu region.

The rivers dammed by the collapse gradually filled their new basins, and the wasteland began its slow transformation. Today, the lake district born from the 1888 eruption is known as Urabandai, or Bandai Highlands. Its centerpiece is Goshiki-numa -- the Five Colored Marshes -- a cluster of lakes and ponds that shimmer in shades of cobalt, emerald, rust, and gold, their colors shifting with the minerals dissolved from the volcanic debris, the angle of light, and the season. The area draws hikers, photographers, and sightseers year-round, a landscape whose extraordinary beauty exists only because a mountain destroyed itself on a July morning more than a century ago.