Jogan Eruption of 864
The Jogan Eruption of 864 (the sixth year of the Jogan era) was the second major eruption of Mt. Fuji in historical times, and more catastrophic than any eruption since. Contemporary chronicles vividly describe plants burning, rocks falling like rain, and lakes hissing with steam. Lava flowed from the mountain’s western flank, creating the vast, level plain now covered by the Aokigahara Jukai Forest and filling in much of the Senoumi lake. Today, Lake Saiko and Lake Shojiko are the once-enormous lake’s last remnants.
In response to the disaster, the imperial court ordered a new shrine built in Kai Province (modern-day Yamanashi Prefecture) to propitiate Asama no Kami, deity of the volcano. Asama no Kami was already being worshiped at a shrine south of the mountain in Suruga Province (modern-day Shizuoka Prefecture), but the eruption was taken as evidence that this shrine had been lax in its duties.
Although decisive evidence is lacking, researchers today suspect that this newly created shrine was the forerunner of today’s Kawaguchi Asama-jinja Shrine on the far shore of Lake Kawaguchiko. Tellingly, the shrine is oriented toward the source of the lava flow rather than Mt. Fuji’s peak. This was the beginning of the religious infrastructure on the mountain’s northern flank that would, centuries later, welcome thousands of lay pilgrims every year.
