|
Position Latitude
Northern latitude of 35° 21' 39" East Longitude of 138° 43' 39"
(The position at the second triangulation point on the top of Mount Fuji.)
Altitude
3,775.6m
(The height at the second triangulation point on the top of Mount Fuji. The second highest in Japan is the Kitadake (Yamanashi Prefecture), 3,193m.)
Weather
- Average temperature: -6.6℃
- Average snow depth: 188cm
- Average number of snowy days: 243 days
- Average wind velocity: 12m/s
(on the mountain top)
|
|
|
Physiognomy/geology
Magma has made Mount Fuji Japan's highest mountain
Mount Fuji is positioned on the point where three tectonic plates meet; one from
the Philippines, another from Eurasia and the other from North America. In addition,
Mount Fuji is positioned almost at the top of the inverted wedge-shaped Nankai Trough
that is bent into two parts (one part is called Suruga Trough, the other Sagami Trough)
on the northern edge of the Philippine Sea Plate. It is considered, therefore, that a
huge volume of basaltic magma was supplied to make Mount Fuji such a present high mountain.
The middle to the foot of Mount Fuji is in an oval shape stretching from north-northwest to
south-southeast. Many of its over 100 parasitic cones, being the largest number that a mountain
has alone in Japan, line on this direction.
It is because the Philippine Sea Plate and Eurasian Plate hit each other and magma ascended along the cracks made by the pressures.
Distribution of techtonics plates and active volcanoes around Japan
|
|
Birth and Growth
Before the advent of Mount Fuji (40,000 - 100,000 years ago), Komitake Volcano (near the
end point of the Subaru Line road), Ashitaka Volcano and Hakone Volcano were active in this area.
Mount Fuji emerged at the foot of Komitake Volcano around 100,000 years ago. Then later,
explosive eruptions about 80,000 - 20,000 years ago created a volcano as much as 3,000 meters
high, called as Ko-Fuji (Old Fuji) Volcano. And around 10,000 years ago (or 17,000 years ago
according to another estimation) a large volume of lava erupted from the mountain top, which
almost covered Ko-Fuji Volcano to create Shin-Fuji (New Fuji) Volcano. This activity mostly formed
the current Mount Fuji (It is assumed to be 6,000 - 3,500 years ago).
Later, Mount Fuji continued to be active. According to records, Mount Fuji repeated eruptions
about ten times since the 8th century. (These eruptions occurred at the parasitic cones.) The
big eruptions among them were the one in the period of Jougan 6 - 8 (864 - 844) and the one in
the period of Hoei 4(1707). The former made the Aokigahara Lava Flow break the "Se-no-Umi
(Se-no-ko)" into two, i.e., Lake Shojin and Lake Sai. The latter emitted a large volume of ejecta
over the eastern slopes, reaching up to Edo area. Even 300 years later now, some areas have not yet
regained vegetation.
On the other hand, eroded valleys/cleavages called Osawa-Kuzure developed along the western slopes at
least 1,000 years ago. About 10,000 tons of earth and sand are still flowing away from the valley at
present. Due to snow melting or downpour of rain, the earth and sand may cause avalanche of rocks and
earth.
Lavas created Mount Fuji
Since the lava of Mount Fuji is basaltic, which is less sticky and flows easily, it formed long skirts
with a moderate slope (4-5°). The steep slopes (30°) from the 8th station upward were formed when lava
emitted out from the mountain top became solid while sticking on the mountain with proper viscosity.
As a result, Mount Fuji with beautiful ridge lines was formed.
Due to the conditions at that times that triggered the lava flow, peculiar landscapes were produced, such
as lava tunnels and lava tree molds. In addition, the surface layer and lower base of the lava flow of
Shin-Fuji are composed of about seven layers, about 30 meters in thick. Since they are like clinker
(porous sections), a large volume of rainwater (assumed to be approximately 2.2 - 2.5 billion tons) that
fell down on Mount Fuji got in there, turned to artesian groundwater and streamed out at the edges of
the lava flow, offering rich water to people at the foot of the mountain.
|
|
Animals and Plants
Mount Fuji is a precious place where we can continuously observe the vertical distribution of vegetation
zones. Moreover, since the tough natural environment covered with tephra (pyroclast) compresses the vertical
distribution of animals and plants, you cannot observe alpine plants anymore at a lower altitude than at other
mountains. In addition, even at the same altitude, vegetation varies depending on the timing of eruption or the
components of lava. The forest line of Fuji is said to be around at 2,400-meter elevation but it varies depending
on location.
The vegetation in a rich variety makes the place an optimum habitat for many birds. About a quarter of all avian
species in Japan, about 160 species, are confirmed to live there.
It is fact that the Japanese monkey and alpine mammal species do not make their habitats on Mount Fuji but 37 mammal
species reside there (a majority of medium-sized or larger mammals distributed in the main land, Shikoku and Kyushu
live there). On the other hand, the number of amphibian species and reptiles that live there is small due to limited
surface stream water.
|
