The Sacred Stratovolcano.

Mount Fuji is more than Japan’s highest peak; it is a structural marvel formed by the intersection of three major tectonic plates.

Mount Fuji is a classic **Stratovolcano**, known for its near-perfect symmetrical cone. This shape is the result of alternating layers (strata) of hardened lava and volcanic ash. It sits at a "Triple Junction" where the Amurian (Eurasian), Okhotsk (North American), and Philippine Sea plates converge, creating a constant supply of magma from the subducting oceanic crust.

Evolutionary Stages

The Fuji we see today is actually the "Young Fuji," which began forming roughly 10,000 years ago. It sits atop two older volcanoes: **Komitake** and **Old Fuji**. Over millennia, the eruptions from Young Fuji completely covered its predecessors, creating a massive basaltic edifice that dominates the Kantō region.

The Sleeping Giant

While Fuji has not erupted since the **Hōei eruption of 1707**, it is classified as active. The 1707 event was unique because it did not occur at the summit; instead, a massive new crater opened on its flank. Today, Fuji is one of the most monitored volcanoes on Earth, as its proximity to Tokyo (just 100km away) makes it a critical focus for volcanic hazard mitigation.