When Did Mt. Fuji Last Erupt?

Mt. Fuji is a well-known mountain in Japan, but it’s also a volcano. Mt. Fuji’s last eruption was not so long ago—and scientists are predicting that it’s long overdue for another eruption event!  Fuji has been an active volcano for thousands of years, and written history has recorded many of the eruptions that occurred on Mt. Fuji over time.

The notorious last eruption of Mt. Fuji began with a huge earthquake on November 11, 1707. For miles around the epicenter, Japanese people felt the effects of this earthquake, particularly in the city of Osaka. People knew that Mt. Fuji could be expected to blow at any time, but the explosion was no less than historic.

The Great Hoei Eruption, as it is now known, occurred between mid-December and early January of 1707-1708, causing earthquake-like tremors for miles around and strewing huge amounts of ash and cinder. On the fateful day of December 16, 1707, Mt. Fuji began belching up ash and cinder. The explosions continued for a period of more than two weeks, spitting up hundreds of millions of cubic feet of volcanic ash, which was spread for miles and miles to the east of the mountain.

To put the range of the explosion into context, ash even fell in the city of Tokyo nearly 90 miles away! This eruption is still remembered today for its notoriety, which created three new vent holes in the volcanic mountain.

To this day, Mt. Fuji has a giant crater on its one flank, caused during the huge eruption in late 1707.

Creation of Mt. Fuji

Volcanic mountains usually do not start out as mountains—rather, continuous eruptions over time cause them to grow bigger and bigger as the magma and lava cool into solid rock.

In an earlier era, the mountain erupted over thousands of years, finally forming into a cone over half of a mile high. Once the volcano had spent a few thousand active years growing and growing, it stopped, and for a period of about 4000 years, it apparently sat dormant.

About 5000 years ago, the mountain entered its current era of renewed activity, and the era of “New Fuji” began. Four explosions occurred over the subsequent period until written history tells us of an event about 2300 years ago, causing liquid mud to be spilled in the nearby city of Gotemba.

In the year 864, a well-documented explosion occurred which rocked Japan for a period of ten days, during which dozens of people were killed and their homes obliterated.

Future Eruptions

Scientists believe that Mt. Fuji is about due for another seismic event. A government report done a few years ago determined that if Fuji were to erupt, it could cost tens of billions of dollars in damage, causing it to be one of the most closely monitored volcanoes in the world.

A series of tremors and earthquakes recently have pointed to an upwelling of magma deep within the structure of the volcano, hinting that the majestic Mt. Fuji may be reaching the zero-hour for another colossal explosion.

A major earthquake in the 1850s was the last large event observed around Mt. Fuji, and scientists expect that a new event could occur very soon. Although citizens living around Mt. Fuji do not believe that the volcano will become active again anytime soon, it is far from dormant, and another eruption may be just around the corner.