Most Recent Eruption of Mount Fuji.

The 1707 eruption of Mount Fuji, known as the H?ei eruption, was the most powerful volcanic event in Japan’s recorded history. It began on December 16, 1707, just weeks after a massive earthquake along the Nankai Trough, which likely destabilized magma beneath the volcano. Unlike Fuji’s typical summit eruptions, this event opened a new vent on the southeastern flank of the mountain, now called the H?ei Crater. The eruption was explosive rather than lava-driven, blasting enormous quantities of ash, pumice, and volcanic rock into the atmosphere.

Ash fall from the eruption was widespread and devastating. Thick layers of ash buried farmland across several provinces, including Suruga, Sagami, and Musashi, and even reached Edo (modern-day Tokyo), over 100 kilometers away. Rivers became clogged with volcanic debris, increasing flooding for years afterward, while crops failed repeatedly due to contaminated soil. Although remarkably few direct deaths were recorded, the long-term effects caused famine, economic hardship, and social unrest, making the eruption far more destructive over time than its immediate impact suggested.

The H?ei eruption is especially significant because it marked Mount Fuji’s last eruption to date, and it reshaped how Japan understood volcanic risk. The event highlighted the connection between major earthquakes and volcanic activity, a relationship that remains a key focus of modern geophysical research. Today, the H?ei Crater is still visible on Fuji’s slopes, serving as a reminder that the iconic mountain is not extinct but dormant—and that its serene appearance hides a history of sudden and transformative power.