Mount Fuji is a dormant volcano which is the tallest peak in Japan. The latest eruption of Mount Fuji was triggered by an earthquake in 1707. [1] The mountain as it appears now is known as the "New Fuji volcano", which began to erupt about 10,000 years ago. Under the "New Fuji volcano" lies the "Old Fuji volcano", which was active between 100,000 years ago and 10,000 years ago, and the "Komitake volcano", which became active 700,000 years ago.
There has been volcanic activity in the vicinity of Mount Fuji for several million years. The earliest geologically known volcano was Mount Komitake (小御岳火山, small mountain volcano) that became active 700,000 years ago. Another volcano to the south-east of Mount Fuji—known as Mount Ashitaka (愛鷹山)—was also highly active throughout the period. The peak of Komitake is about 2,300 meters (7,500 ft) above sea-level on the north face of Mount Fuji (at the fifth station).
Komitake entered another period of activity around 100,000 years ago. This created a new volcano known as Old Fuji (古富士, kofuji, Old Fuji) that reached a height of 3,100 meters (10,200 ft). It created many explosive eruptions that threw out large amounts of scoria, volcanic ash and lava.
Following the Old Fuji period, there were about 4,000 years of inactivity, ending at around 5,000 years ago, when Mount Fuji became active again; this period is known as New Fuji (新富士, shinfuji), and continues to the present day. Eruptions of New Fuji exhibit phenomena such as lava flows, magma, scoria, volcanic ash, collapses and side eruptions, leading it to be called "a department store of eruptions". Ash from New Fuji is often black, and eruptions are new in terms of geological layers. Valuable data on the activity of Mount Fuji is recorded in Japanese historical documents dating from the 8th century onwards. It exhibits a range of representative eruptions.
About 2,300 years ago the east face of the volcano collapsed and lahars flowed down to the Gotemba area as far as the Ashigara plain in the east and the Suruga bay across Mishima city in the south. This incident is now called the Gotemba mud flow (御殿場泥流, Gotemba deiryū). Liquid mud piled up over an area as wide as the city area of Mishima.
In 864 (the 6th year of the Jōgan era) there was an eruption on the north-east side of Mount Fuji, which produced a great amount of lava.
The latest eruption, in 1707 (the 4th year of the Hōei era), was known as the great Hōei eruption. It followed several weeks after the Great Hōei earthquake, an 8.7 on the Richter scale. The earthquake severely damaged the city of Osaka, but more than that, it created enough seismic activity to compress the magma chamber 20 km deep in the inactive Mt. Fuji. Due to the compression of the magma chamber, basaltic lava rose from the bottom to the higher dacitic magma chamber at 8 km deep. The mixing of the two different types of magma caused a Plinian eruption to occur. Previous to the Hoei, another earthquake named Genroku had struck Japan in 1703. The earthquake affected both Kanagawa and Shizuoka prefectures, and was measured as an 8.2 on the Richter Scale. The Genroku earthquake had a similar effect on Mt. Fuji as Hoei but with less severity. It clamped the dike of the mountain at 8 km to the surface (where the dacitic magma resides), as well as the basaltic chamber at 20 km deep. Many articles found a correlation between the two earthquakes, arriving at the conclusion that without either earthquake the Hoei eruption would not have happened.
Sixteen eruptions of New Fuji have been recorded since 781. Many of the eruptions occurred in the Heian era, with twelve eruptions between 800 and 1083. Sometimes inactive periods between eruptions lasted for hundreds of years, as in the period between 1083 and 1511, when no eruptions were recorded for over 400 years. At present, there have been no eruptions since the Hoei eruption in 1707–1708, around 300 years ago.
Scientists study the activity of the magma rising by measuring CO2 emissions in the deeper parts of the volcano. Studies from before the 2011 Tohoku earthquake show the CO2 emissions below 5 gCO2/m3/day, which is the detection limit. If the emissions rise above 5 gCO2/m3/day then seismic activity is occurring and an eruption could possibly take place. According to a five-stage evolutionary model for the release of volcanic gas, Mt. Fuji would be considered stage I. Magma is at a considerable 10 km (6.2 mi) depth and no emissions of gases can be observed regularly.
Following the 2011 Tōhoku earthquake and tsunami, much attention was given to the volcanic reaction of Mount Fuji. Experts have found that the internal pressure of the Mount Fuji magma chamber has increased to an estimated 1.6 megapascals, raising speculation over the possibility of an eruption. The financial damage to Japan from a Fuji eruption is estimated at ¥2.5 trillion (about $25 billion). [6] [7]
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. The process that forms volcanoes is called volcanism.
Mount Fuji is an active stratovolcano located on the Japanese island of Honshu, with a summit elevation of 3,776.24 m. It is the highest mountain in Japan, the second-highest volcano located on an island in Asia, and seventh-highest peak of an island on Earth. Mount Fuji last erupted from 1707 to 1708. The mountain is located about 100 km (62 mi) southwest of Tokyo and is visible from the Japanese capital on clear days. Mount Fuji's exceptionally symmetrical cone, which is covered in snow for about five months of the year, is commonly used as a cultural icon of Japan and is frequently depicted in art and photography, as well as visited by sightseers, hikers and mountain climbers.
A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and explosive eruptions. Some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high to intermediate levels of silica, with lesser amounts of less viscous mafic magma. Extensive felsic lava flows are uncommon, but can travel as far as 8 km (5 mi).
The Ring of Fire is a tectonic belt of volcanoes and earthquakes.
Asahito, posthumously honored as Emperor Higashiyama, was the 113th emperor of Japan, according to the traditional order of succession. Higashiyama's reign spanned the years from 1687 through to his abdication in 1709 corresponding to the Genroku era of the Edo period. The previous hundred years of peace and seclusion in Japan had created relative economic stability. The arts flourished, including theater and architecture.
Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption. Types of volcanic cones include stratocones, spatter cones, tuff cones, and cinder cones.
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts. It is typically dark in color, and basaltic or andesitic in composition. Scoria has relatively low density, as it is riddled with macroscopic ellipsoidal vesicles, but in contrast to pumice, scoria always has a specific gravity greater than 1 and sinks in water.
Mount Asama is an active complex volcano in central Honshū, the main island of Japan. The volcano is the most active on Honshū. The Japan Meteorological Agency classifies Mount Asama as rank A. It stands 2,568 metres (8,425 ft) above sea level on the border of Gunma and Nagano prefectures. It is included in 100 Famous Japanese Mountains.
Sakurajima is an active stratovolcano, formerly an island and now a peninsula, in Kagoshima Prefecture in Kyushu, Japan. The lava flows of the 1914 eruption connected it with the Ōsumi Peninsula. It is the most active volcano in Japan.
Hōei was a Japanese era name after Genroku and before Shōtoku. This period spanned the years from March 1704 through April 1711. The reigning emperors were Higashiyama (東山天皇) and Nakamikado (中御門天皇).
Plinian eruptions or Vesuvian eruptions are volcanic eruptions marked by their similarity to the eruption of Mount Vesuvius in 79 AD, which destroyed the ancient Roman cities of Herculaneum and Pompeii. The eruption was described in a letter written by Pliny the Younger, after the death of his uncle Pliny the Elder.
The Hōei eruption of Mount Fuji started on December 16, 1707 and ended on February 24, 1708. It was the last confirmed eruption of Mount Fuji, with three unconfirmed eruptions reported from 1708 to 1854. The eruption took place during the reign of Emperor Higashiyama and the Shogun was Tokugawa Tsunayoshi. It is well known for the immense ash-fall it produced over eastern Japan and subsequent landslides and starvation across the country. Hokusai's One Hundred Views of Mount Fuji includes an image of the small crater at a secondary eruption site on the southwestern slope. The area where the eruption occurred is called Mount Hōei because it occurred in the fourth year of the Hōei era. Today, the crater of the main eruption can be visited from the Fujinomiya or Gotemba Trails on Mount Fuji.
Prediction of volcanic activity, and volcanic eruption forecasting, is an interdisciplinary monitoring and research effort to predict the time and severity of a volcano's eruption. Of particular importance is the prediction of hazardous eruptions that could lead to catastrophic loss of life, property, and disruption of human activities.
Nazko Cone is a small potentially active basaltic cinder cone in central British Columbia, Canada, located 75 km west of Quesnel and 150 kilometers southwest of Prince George. It is considered the easternmost volcano in the Anahim Volcanic Belt. The small tree-covered cone rises 120 m above the Chilcotin-Nechako Plateau and rests on glacial till. It was formed in three episodes of activity, the first of which took place during the Pleistocene interglacial stage about 340,000 years ago. The second stage produced a large hyaloclastite scoria mound erupted beneath the Cordilleran Ice Sheet during the Pleistocene. Its last eruption produced two small lava flows that traveled 1 km to the west, along with a blanket of volcanic ash that extends several km to the north and east of the cone.
The Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 miles (1,100 km). The arc formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River which is the northward limit of the Cascade Range proper.
Several types of volcanic eruptions—during which material is expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.
Kaimondake, or Mount Kaimon, is an undissected volcano – consisting of a basal stratovolcano and a small complex central lava dome – which rises to a height of 924 metres above sea level near the city of Ibusuki in southern Kyūshū, Japan. The last eruption occurred in the year 885 CE. Because of its conic shape, Mt. Kaimon is sometimes referred to as "the Fuji of Satsuma".
A cinder cone is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is symmetrical; with slopes between 30 and 40°; and a nearly circular ground plan. Most cinder cones have a bowl-shaped crater at the summit.
The 1707 Hōei earthquake struck south-central Japan at around 13:45 local time on 28 October. It was the largest earthquake in Japanese history until it was surpassed by the 2011 Tōhoku earthquake. It caused moderate-to-severe damage throughout southwestern Honshu, Shikoku and southeastern Kyūshū. The earthquake, and the resulting destructive tsunami, caused more than 5,000 casualties. This event ruptured all of the segments of the Nankai megathrust simultaneously, the only earthquake known to have done this, with an estimated magnitude of 8.6 ML or 8.7 Mw. It possibly also triggered the last eruption of Mount Fuji 49 days later.
A volcanic hazard is the probability a volcanic eruption or related geophysical event will occur in a given geographic area and within a specified window of time. The risk that can be associated with a volcanic hazard depends on the proximity and vulnerability of an asset or a population of people near to where a volcanic event might occur.
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