Pyroclastic rivers: The Hôei Fuji Eruption (1707)

In the morning of 23.11.Hoei 4 (16.12.1707) accompanied by loud sounds of explosions, there arose from Mt Fuji a column of what looked like belching black smoke rising to an altitude of some twenty kilometres. It was, however, not just smoke but mostly volcanic fall-out or tephra, containing rocks and pebbles of various sizes, and marked the onset of the volcano's most violent eruption in recorded history. This chapter shows the dimensions of the eruption using contemporary reports of the event together with the scientific analysis of volcanologists. It then examines the response of bakufu to the situation, relying chiefly on records left by the locally affected population, containing details not found in the official government record.