Mount Fuji Geology

Scientists have identified four distinct phases of volcanic activity in the formation of Mt. Fuji. The first phase, called Sen-komitake, is composed of an andesite core recently discovered deep within the mountain. Sen-komitake was followed by the “Komitake Fuji,” a basalt layer believed to be formed several hundred thousand years ago. Approximately 100,000 years ago, “Old Fuji” was formed over the top of Komitake Fuji. The modern, “New Fuji” is believed to have formed over the top of Old Fuji by around 10,000 years ago. The volcano is currently classified as active with a low risk of eruption. The last recorded eruption occurred in very recent geological time of 1707 during the Edo period. At this time, a new crater, along with a second peak, named Hōei-zan after the era name, formed halfway down its side. Mt. Fuji is where the Eurasian Plate (or the Amurian Plate), the Okhotsk Plate, and the Philippine Plate meet. They form the western part of Japan, the eastern part of Japan, and the Izu Peninsula respectively.   (Article based on Wikipedia article and used under the GNU Free Documentation License) |