An ordinary person does not see much difference between “extinct” and “dormant” volcanoes. In fact, the differences are quite significant, because a conditionally “dormant” volcanic formation can suddenly awaken, and then no one will find it interesting.
Another thing is that they are completely safe, which is actively used by travel companies and outdoor enthusiasts. What are the main features of extinct volcanoes?
Physics of a volcanic eruption - how it becomes extinct
The eruption occurs due to the presence in the magma not only of water vapor, but also of various gases: hydrogen chloride and fluoride, oxides of sulfur and methane, nitrogen, carbon dioxide, etc.
In a "sleeping" volcano, the concentration of gases dissolved in the magma corresponds to the level of pressure under which the magma is located at a certain depth. In this way, a state of balance is maintained.
However, due to earthquakes that shift sections of the crust, a decrease in pressure may occur, for example, in the area of the magma chamber. The equilibrium state is disrupted and the gases immediately increase in volume due to the transition to the gaseous state.
The foamed magma begins to move upward, which leads to an even greater drop in pressure, and therefore to an acceleration of the process of gas release from the magma.
Accordingly, the probability of his awakening tends to zero.
List of famous extinct volcanoes in the world
Volcanoes, which pose no threat, are located on all seven continents: North and South America, Asia, Africa, Europe, Antarctica and Australia.
Today there are over two hundred extinct volcanoes in the world. The most typical representatives of this type are presented below.
Rocky
This extinct volcano is located on the Kamchatka Peninsula, in the very center of the Sredinny Range. The highest point of the volcano is at 1759 meters above sea level.
According to geologists, last time Stony became active approximately two and a half million years ago. The volcano was formed by lava flows and pyroclastic rocks. The volcanic shape in the form of a gentle cone ends not with a crater destroyed due to erosion, but with a steep peak.
Arayat
Located in Luzon - largest island Philippines. The highest point is 1025 meters.
Last eruption happened, most likely, about 10 thousand years ago. Despite the erosion that has affected the northern and western parts of the crater, it still remains on top.
Damavand
Located in the Iranian province of Mazandiran and is the largest highest point Elburz mountain system (5620 meters above sea level). The last eruption was recorded around 5350 BC.
Damavand has the shape of a gentle cone and rises one and a half kilometers above Elborz. The volcanic cone arose due to andesite lava, but there are also glaciers on the slopes.
Sajama
Located in Bolivia, in the Central Andes. The highest point above sea level is 6542 meters. Sahama is part of the same name National Park, located near the Chilean border.
Exact date last activity is not known for certain, but many scientists insist on the era of the Quaternary period Holocene, i.e. about 12 thousand years ago.
Sahama is a classic cone-shaped stratovolcano, composed of hardened lava and its debris. At an altitude of more than 6000 meters, it is covered with never-melting snow and ice.
Aconcagua
The highest extinct volcano is considered to be located in the same Andes, but on Argentine territory. The peak is located at 6961 meters above sea level.
Aconcagua, it is considered not only a record holder among its peers, but also the highest point of the southern and western hemispheres. For these merits, he was even included in the “Seven Summits” list of the highest peaks in six parts of the world.
Aconcagua is also one of the oldest volcanic formations on the planet.
The exact date is unknown, but many scientists conclude that it arose approximately 150 million years ago.
Excursions to extinct volcanoes
A traditional excursion lasts 1-2 days and involves either climbing to the peaks by helicopter or climbing on foot.
Some volcanoes are even equipped with special areas where tourists can take a break and enjoy the natural views from great heights.
Extinct volcanoes are not only a living reminder of great power nature.
Thanks to them a large number anywhere in the world, anyone can organize an appropriate tour and get an unforgettable experience.
Once upon a time, when I was still a child, I was interested in this natural phenomenon How volcano. Why does an ordinary mountain suddenly get tired of being submissive and declare to the despicable human race " day of wrath", leaving behind the earth crucified by fire, a crimson glow, tears and bitter ash. Even today no one will give me an objective and accurate answer to this question, because this is one of the most mysterious natural phenomena. But for that, I learned that volcanoes are scattered all over the earth like boils, which I will tell you about now.
A little about volcanoes
Volcanoes exist different types, sizes, land, underwater, and also, they are classified according to degree of activity, and divided by:
- active or active;
- sleeping;
- inactive or extinct.
What types of extinct volcanoes exist?
Usually extinct volcanoes those that did not erupt are considered years So ten thousand, no more, no less. But it also happened that suddenly dormant volcanoes took residents by surprise.
- Ship Rock in New Mexico. Is particle a once active volcano, but now extinct. Rains, winds and others natural phenomena dispelled top part volcano, leaving only channel with frozen in it magma.
- famous lock,built on the remains extinct three hundred forty million years ago volcano A brave act.
- can boast Puy de Dome department, where is located over two hundred extinct volcanoes, which may have been active two million years ago.
Also, sometimes volcanoes that erupted not so long ago, but on a very small scale, are considered extinct. These include:
- Ararat. This mountain is now located on Turkish lands, But once belonged to the Armenians for whom he has long become symbol.
- Elbrus. The inactivity of this volcano can be disputed, since the last time it erupted was in the first century AD.
- Kazbek. It is also considered inactive, despite the fact that it erupted in six hundred and five and ten BC. Well, time will judge who is right.
A volcano is a geological formation that often resembles a mountain. Volcanoes differ from mountains in that they have an opening extending below earth's crust. This means that volcanoes have direct access to lava and gases stored underneath. earth's surface, and can therefore release these elements into the atmosphere. This article examines the main differences between active, dormant and extinct volcanoes.
Active volcanoes
Currently, researchers do not agree with official definition active volcanoes. However, they are often considered to be geological features that have had some activity within the last 10,000 years. In other words, active volcanoes are those that have erupted since the last ice age. Weak point This definition, according to critics, is that volcanoes that have awakened in the last few thousand years are unlikely to become active in the near future. Other definitions of active volcanoes stipulate that the object must currently be showing some activity, not just having erupted in the past. Such activity may include frequent seismic activity as tectonic plates begin to shift around the base of the volcano. This movement may release significant amounts of carbon dioxide, sulfur dioxide or other gases into the atmosphere.
Examples of currently active volcanoes include: Mount Etna (Sicily, Italy); Nyiragongo (Democratic Republic of Congo); and Kilauea (Hawaii, USA).
Dormant volcanoes
Dormant volcanoes are usually considered active volcanoes, because they have been erupting since the last ice age but are not currently active. The dormant volcano may erupt again at some point in the future. Some scientists suggest that the volcano is dormant rather than extinct if there is some evidence of its past activity. Other researchers believe that dormant volcanoes are geological features that have not erupted since the last ice age, but are expected to occur in the future. Scientists suggest that climate change may trigger the eruption of some dormant volcanoes. This reactivation could occur if severe weather conditions change the pressure of nearby ocean waters, which could lead to volcanic activity and possible eruptions.
Examples of dormant volcanoes include: Fourpeak (Alaska, USA); Pinatubo (Philippines) and Soufriere Hills (Montserrat).
Extinct volcanoes
Unlike dormant volcanoes, extinct volcanoes did not erupt during the last ice age, which ended approximately 10,000 years ago, and are not expected to erupt again in the future. Although the dormant volcano is not expected to ever flare up again, several geological and seismic data show that this assumption is not always correct. An example of this is Forepicd in Alaska, mentioned above. This volcano was considered dormant until 2006, when it began to show signs of activity and is now classified as dormant. The definition of an extinct volcano is based on the calculated assumption that it no longer has a lava source, but this cannot be determined with absolute certainty.
Volcanoes believed to be extinct include: Zuidval (Netherlands); Hawaiian Ridge (Hawaii, USA); and Kulal (Kenya).
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For common man, who knows little about volcanology, the difference between a dormant and an extinct volcano is small. You might think that the mountain has stopped its volcanic activity forever, but in fact it is just sleeping and can wake up at any moment. What do volcanologists think about this? What differences do they see between an active, extinct and dormant volcano?
Active volcanoes
In fact, these concepts are quite subjective. The easiest way to deal with an active volcano is any giant that is at the moment pours out lava, throws out ash and smoke. Some volcanoes may not show outward signs of eruption, but are still considered active because they regularly tremble, produce earthquakes, and emit colorless gases. At the moment, we can call them active in Indonesia.
Lava on Kilauea
According to the US Geological Survey, any volcano that has erupted over a period of time is considered active. historical period time. Although many of them are rather “potentially active” (which is closer to the concept of “dormant”), since they do not show any signs of activity. These could be considered, for example, before its eruption in 2014.
Dormant volcanoes
When it comes to dormant (inactive) volcanoes, their definition becomes more difficult. The USGS says a dormant volcano is one that shows no signs of disturbance but may become active again. A striking example such a giant stands out. He is currently considered dormant, but only until increasing levels of anxiety make him active again.
It is quite difficult to determine the line between inactive and extinct volcanoes. This is due, first of all, to their resting time. Some peaks can sleep for tens or even hundreds of thousands of years, but if they have sufficient potential for eruption and can erupt again, then it would be reckless to call them extinct.
Extinct volcanoes
The body of magma in any volcano has large sizes, and its temperature reaches 700 °C. It takes quite a long time for this entire mass to cool down - sometimes from 1 to 1.5 million years. As a rule, a volcano that last erupted at least 1 million years ago can be considered extinct. For example, the peaks of Sutter Butte and Clear Lake in California have been silent for 1.4 million years. With a high probability they will no longer erupt, but this does not mean that over time new volcanoes will not arise in their place.
If you look at the history of the Baker or Lassen Peak volcanoes in the Cascade Mountains, you can see that they appeared on the remains of ancient volcanoes that had not erupted for many millions of years. It is believed that if once a volcano grew in a specific place, then in the future new cones will appear here, since in this area there is the most preferable path for the movement of magma.
Thus, we can conclude that if a volcano makes noise, it means it is active. If it erupted in the not so distant past, but is now silent, then it is sleeping, and if its last volcanic activity occurred more than a million years ago, then it is extinct. Of course, the differences are approximate, but this is approximately how volcanologists look at the life of volcanoes.
Walk on the body of a dormant volcano in Crimea, capable of destroying vast territories in an explosion, and then find out that it is the oldest dormant volcano in the world and 150 million years ago has already significantly changed everything in these places., writes Sergei Anashkevich
But many of you have been here once. And they walked.
Karadag, southeast Crimea. One of the most beautiful and legendary places on the peninsula.
And a giant sleeping natural bomb.
A view familiar to many vacationers in Crimea is the Karadag massif, prominent far into the sea, on the horizon. Looking at it from this point, you cannot immediately say that a volcano once erupted here, completely changing the landscape of the vast surrounding areas...
Kiev volcanologist Stepan Romchishin says that the Karadag volcano did not die 150 million years ago, but could potentially wake up now - “If Karadag explodes, Crimea will not exist by the end of the day. A cloud of volcanic ash will destroy all life as far as Dnepropetrovsk. The ash column will rise 50 kilometers, and magma will flow out for several days. During an eruption, a cavity is formed under the volcano, so it falls into the abyss and then explodes. The power of such a volcano can be equated to one hundred atomic bombs.”
The scientist assumes that from the explosion, ash heated to 200°C will scatter over a huge area - up to the Russian city of Smolensk in the north and part of the territory of Turkey and other Black Sea countries in the south, west and east. Speed sea wave will reach 400 km/h.
For example, the last one powerful eruption The volcano, according to scientists, was 74 thousand years ago in New Zealand. It almost became fatal for humanity. Millions of tons of ash and sulfur were released into the air. Temperatures around the world dropped by 15 degrees. The ash hung in the atmosphere and did not allow the sun's rays to pass through. Sulfur rains destroyed almost all the forests in Asia. Then it took more than 300 years to restore nature.
Karadag is very different from all other mountain ranges in Crimea. A chaotic pile of ominous black rocks directed in different directions, inaccessible gorge and failures, stone walls plunging into the sea and forming bays inaccessible from the shore, harsh stone figures of the Metro City.
All this is a consequence of the volcano that was active here 150 million years ago.
Varied and unusual shapes relief of a volcanic massif with very complex geological structure have already arisen in more than later periods during weathering and erosion. The gentle and flat continental slope of the Coast Range is protected, like armor, from destruction by a powerful, extensive lava flow...
The modern bowl of Karadag (and if you look at the heights of Karadag, today it is precisely a bowl, the walls of which consist of ridges and peaks) is very diverse in both relief and landscape. Standing at one point, looking in one direction, you will see quite familiar mountain peaks overgrown with grasses and shrubs, forming a fairly familiar Crimean landscape, and looking in the other direction...
...you will see rocks Dead City, on which for many thousands of years at least some vegetation could barely cling. And that’s not true everywhere.
Varied in appearance and mineral composition, the volcanic rocks of Karadag were formed during the solidification of lava. Pillow lava flows are very common.
This is a chaotic accumulation of lava segregations of pillow-shaped, ellipsoidal and balloon-shaped shapes with smooth contours, and each of them has a continuous cooling surface with a hardening crust.
Pillow flows are especially spectacular on the southern slope of the Magnetic Ridge, along which they stretch obliquely in the form of powerful inclined stone walls. There are seven streams with a capacity of 15–25 m each.
The most diverse lava compositions are on the slopes of the Karagach ridge. There are five types of rocks here, connected by gradual transitions. The change of rocks from bottom to top occurs in the following order: keratophyre – partially albitized porphyrite – porphyrite – bipyrooxene andesite – glassy andesite. It is from these that the famous King Rocks are made.
But based on the name and types of rocks, so as not to make a hole in my and your brain, I will just say that there are some incredible numbers of them here.
Each rock has its own way of shaping rocks and stones into a variety of shapes.
Separately, it is worth mentioning the various craters and places where lava comes to the surface. There are several remains of craters on Karadag. The most famous of them is the Devil's Fireplace.
Perfectly preserved, spectacular, with a beautiful classical concentric shape - a wonderful example of a subvolcanic body.
Here is another part of the giant circle - Parus rock
Separately, it is worth mentioning the numerous dikes.
A dike is a frozen plate-shaped magma intrusion, prepared by weathering from the surrounding less resistant rocks. The most famous Karadag dike is the Lion's Dike.
Located under the Devil's Kamin crater, it is surrounded by several other small and one large dike. In addition, the structure of the Coast Range in relation to the Khoba-Tepe ridge allows scientists to assume that it was here that the main vent of the volcano was located.
Sometimes there is an entire “stone forest” of giant crenellations, peaks and stone teeth that form in thick layers of volcanic tuff, dissected by vertical cracks. These are all the dikes surrounding the Lion's Dyke
Some of them literally cut through mountain ranges. And weathering over many thousands of years on both sides of the ridge formed gorges.
Under some of the ridges that “descended” from the mountains, caves, including underwater ones, were formed. One of them is the Thundering Grotto. It was the sounds from this grotto that formed the famous legend about the Karadag snake, which someone seemed to have once seen, and many often heard its roar in the fog. This legend even formed the basis of the story “Fatal Eggs” by Mikhail Bulgakov.