Dormant volcano refers to a volcano that has erupted in history but has been in a relatively static state for a long timevolcano。Such volcanoes are well preservedVolcanic coneForm, it still has volcanic activity ability, or it can not be concluded that it has lost volcanic activity ability.
Dormant volcanoes have erupted in history, but they have been in a relatively static state for a long time.
Such as ChinaChangbai MountainIt erupted twice in 1327 and 1658, and there were many activities before that.[1]
Although there is no eruption activity, the volcano is in a dormant state, as high temperature gas is constantly ejected from some unfathomable fumaroles on the hillside.
A volcano that is erupting and is expected to erupt again can of course be called an active volcano.
While those dormant volcanoes, even if active, are not about to erupt, and volcanoes that may erupt again in the future can also be called active volcanoes.Those volcanoes whose last eruption has been a long time ago and is proved not to erupt in the foreseeable future are called extinct volcanoes orExtinct volcano。
There is a "liquid zone" 100 to 150 kilometers below the crust, where there is molten silicate material containing gas volatiles under high temperature and pressure, namely magma.
Once it rushes out of the earth's surface from the weak section of the crust, it forms a volcano.
distribution
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Known on Earth“Extinct volcano”About 2000 seats;A total of 523 "active volcanoes" have been discovered, including 455 on land and 68 underwater volcanoes.
Volcanoes are unevenly distributed on the earth, and they all appear in fault zones in the crust.
Worldwide, volcanoes are mainly concentrated in the Pacific Rim andIndonesiaTo the north, it passes through Myanmar, HimalayasCentral Asiareachmediterranean seaToday, 80% of the active volcanoes on the earth are distributed in these two belts.
Typical representative
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Changbai Mountain, China
Changbai Mountain is a part of the ancient Xia continent. It is a famous dormant volcano. About 600 million years ago, it was a vast oceanProterozoicreachmesozoicAfter the earth experienced the Caledonian East China Sea West, Yanshan and Himalayan orogeny, the sea water finally retreated from this ancient land after many vicissitudes, and the crust of Changbai Mountain area experienced a series of fractures and uplifts, and the underground outflowbasaltThe grout, which was ejected out of the ground along the crustal cracks, revealed the eruption of Changbai Mountain. Although the total energy of the volcanic eruption was weakened, as the ejected magma changed from basic to acidic, the viscosity was increased. When the saturated rigid magma often blocked the volcanic eruption pipeline, the huge force broke through the resistance, and the eruption was carried out in an explosive manner, which became more violent.
Changbai Mountain volcano erupted many times and intermittently for a long time. From the 16th century to 1702, there were three eruptions in August 1597, April 1688 and April 1702, respectively.The last eruption occurred in 1903.[4]
The last time about 300 years ago, the materials from the Changbai Mountain volcano eruption accumulated around the crater, making the Changbai Mountain high into a peak, forming a concentric round volcanic cone. Gray white pumiceashIn addition to the snow accumulated over the years, when viewed from a distance, Changbai Mountain is a snowy peak, hence its name.
difference
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Figure 1
Active volcanoes: volcanoes with active ability, including those that still erupt frequently and those that have not erupted for a long time, but have erupted in human history.[3]
Dormant volcano: a volcano that has not erupted for a long time but will erupt in the future.
It is a sleeping volcano that leaves the crustal movement zone and temporarily stops its activity. Once it enters the crustal movement zone again, it will have the opportunity to erupt again.
It is difficult to draw a clear distinction between it and an active volcano.
Mars dormant volcano
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Figure 2
Indian Space Research Organization(ISRO) recently released the Mars Orbiter (Mom) to take amazing images of Mars, which can show the outline structure of Mars, and the sidePhobos。
Although Phobos is the largest of the two satellites orbiting Mars, its diameter is only 22 kilometers, and it only takes 7 hours to completely orbit Mars.
Because the camera's special filter can show the unique color of Mars.
The latest photos of Mars released by the Indian Space Research Organization show thatArsia Mons It is a huge dormant volcano on the surface of Mars. Volcanic sediments can be seen on the side of Alxa Mountain.
This is a close observation of the surface of Mars. The Indian Mars Orbiter's Mars color camera captured a hugeValles Marineris It is 4000 kilometers long, close to 20% of the circumference of Mars, and is one of the largest canyons in the solar system.
Figure 3
As a part of Sailor Canyon, this area is called "Eos Chaos". The Indian Mars Orbiter has captured the fracture structure on the surface of the canyon. These photos are helpful for scientists to understand the geological structure of local scale on the surface of Mars.
