As a planet that contains a large number of radioactive elements that are constantly decaying and exothermic, and has a fiery "heart" - the earth has always been unstable, and large and small volcanoes occasionally vent the deep radiance of this ancient planet to the outside world. anger. Even after billions of years, the "pulse" of the earth is still full of vitality. Since it only occurs in a relatively fixed area, volcanoes are unfamiliar and frightening to most people in the world. What are the "killers" of volcanoes?
Lava and Fire: Nothing to Look Scary
Speaking of volcanoes, the first thing most people think of is the tumbling, bubbling lava that emits a dark red light. However, this is not the case.
While volcanic lava, usually at temperatures between 800 and 1500°C, can easily burn a person to ashes, it is not difficult for anyone with normal mobility to avoid this outcome: although volcanic lava flows "Invincible" is downright "turtle speed". Depending on the composition of the lava, its viscosity will affect the flow velocity to a certain extent, and most lava flows are only 5-10 km/h, which is comparable to the human walking speed, and some are even slower. As long as they can walk and don't intend to die, they can definitely avoid it. And what the lava destroys is usually those fixed assets that cannot be transferred for a while, such as farmland, forest land, residential area and so on. In addition to this, lava flows can also cause secondary fires.
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has erupted many volcanic activities worldwide, such as Mount Etna, Japan's Sakurajima Volcano, and May's Nyiragongo Volcano.
In the movie "Jurassic World 2", the hero escapes before the lava flow, which vividly shows how slow the lava is.
When Iceland's volcano erupted, a large number of Icelanders went to visit, and there was no tension at all. (Image source: People's Vision)
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The Roman historian Pliny the Younger compared the types of volcanic eruptions after witnessing the eruption of Mount Vesuvius in AD 79. The Plinian eruption is named after the historian.
Krakatoa eruption
Front of Destruction: Volcanic Gases, Volcanic Bombs, Earthquakes
The mass casualties caused by volcanoes are almost all caused by massive eruptions of volcanic gas and volcanic bombs in violent central eruptions. Under the crust, high-temperature and high-pressure lava often contains a large amount of volatile gases, including a considerable amount of water vapor, methane and carbon dioxide, as well as volatile minerals. In particular, various gaseous sulfides such as sulfur dioxide and hydrogen sulfide. Under the circumstance of huge pressure, the highly compressed high-temperature volcanic gas often rushes out of the crater with amazing force, and even simply lifts a part of the volcanic cone, forming a "death blade" that destroys everything.
Volcanic gases are responsible for the vast majority of casualties directly caused by volcanic eruptions. The volcanic gas created by a typical Plinian volcanic eruption can trigger a pyroclastic flow covering hundreds or even thousands of square kilometers, and its propulsion speed can reach 120-200 km/h. Speeds can even exceed 500 km/h, dozens of times faster than most lava flows, making it almost impossible to escape.
These dangerous gas streams, which can reach thousands of degrees Celsius and carry powerful kinetic energy, are enough to incinerate any living things in their path, and are entrained by a large amount of pyroclastic debris - usually from collapsed volcanic mountains, volcanic ash , solidified volcanic rock, and other solid substances that are entrapped in the middle of the road - will act as "shrapnel", further increasing the destructive power. In addition, the toxicity of the volcanic gas itself (especially the various sulfur compounds) can also make it a super chemical weapon. Even if the pyroclastic flow front is avoided, people around can still die from poisoning or asphyxiation due to lack of oxygen.
Because of this, the damage a Plinian/Ultra-Plinian volcano can cause is enormous, especially if it happens to be densely populated around it. As the first Plinian volcano to be observed in detail, the eruption of Vesuvius in AD 79 flattened Pompeii and Herculaneum in one fell swoop, killing tens of thousands of people directly, and burying the entire volcanic ash The city thus became a "specimen" of Rome's heyday. The devastation of the larger hyper-Plinian volcanoes is even more terrifying: the pyroclastic flows of the Krakatoa and Tambora volcanoes in Indonesia left behind a considerable amount of debris even hundreds of kilometers away. Lethal records. Among them, the Krakatoa volcano was directly blown off the entire top of the mountain. After the eruption, its height dropped by more than one-third.
In addition, the lava and semi-molten material thrown into the air will also form an overwhelming rock "storm" after solidification. Under the acceleration of gravity, these volcanic bombs of various shapes and sizes can fly to great distances and threaten people, livestock and buildings on the ground. In Pompeii and Martinique, there are seas A record of ships being hit by volcanic bombs. Many volcanic bombs form "pumice stones" that are less dense than water because they are filled with air bubbles, and large numbers of volcanic bombs are often found in seawater after coastal eruptions have ended.
In addition, earthquakes often occur when volcanic activity begins to become active. Although seismic activity itself can cause some damage, it can also serve as a warning to a certain extent—people who have moved from the surrounding volcanoes because of earthquakes can often avoid those more deadly blows.
The Inescapable Curse: Volcanic Ash
At the beginning of the 20th century, ancient civilization researchers noticed that around 1600 BC seemed to be a very pivotal age. In less than a century, the global civilization map has undergone tremendous changes: the ancient Cretan civilization has fallen into shadow; the Harappan civilization in the Indus Valley has also entered a period of decline; in East Asia, the Luoyang Plain The Central Plains tribal alliance was defeated by the rising merchants in the east; while in the Nile delta, the Hyksos and other Asian nomads marched forward and defeated Middle Kingdom-era Egypt... At first, these upheavals were regarded as a series of isolated events , but in the end, historians found a key clue: Significant climate anomalies occurred across the globe during this period. To be more precise, it was drought and cold that devastated ancient civilizations and drove the nomadic peoples from the steppes of the Eurasian continent to flock to their lands. The source of this climate change is most likely the Crete volcano that erupted during this period.
Although a volcano may seem insignificant compared to the size of the entire planet. But once hundreds of millions of tons of volcanic ash are sent into the atmosphere in the eruption, its subsequent impact is very considerable. In 1815, the Tambora volcano in Indonesia erupted, and the volcanic dust rose to an altitude of more than 40 kilometers, and was quickly sent to all parts of the world by the atmospheric circulation. For more than a year, the ash blocked a large portion of the sunlight, making the sun look like a dim red one-eyed. In 1816, summers all over the world "disappeared": there was a widespread and severe failure of agriculture in the entire northern hemisphere, and in the region between 30 and 40 degrees north latitude, multiple snowfalls were recorded in June of that year. Calculations after the fact showed that as much as 170 cubic kilometers of rock and ash were thrown into the air by the volcano. More than 1,000 kilometers northwest of the volcano, the ash falling on the surface is still several centimeters deep!
While Tambora, which took away an entire summer and sparked years of recession and crop failures, is a "big guy," it barely has a VEI-7 rating on the Volcano Eruption Index. In theory, the eruption of a true supervolcano would be enough to plunge the Earth into a long winter for decades -- and it would be fatal to human civilization.
① Harvest failure
refers to the low yield of crops, fruits or aquatic products.
The smoke and ash released by the Indonesian volcanoes reached a height of 5 kilometers. (Image source: People's Vision)
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Volcanic Explosivity Index (VEI) is a scale proposed by Professor Newhall of the US Geological Survey and Stephen Self of the University of Hawaii at Manoa in 1982 to measure the volume of ejecta, volcanic cloud and qualitative observations are used to measure the intensity of volcanic eruptions. The non-explosive eruption intensity is 0, and each 1-level increase in the index means that the volcanic eruption is 10 times more powerful. The largest volcanic eruption in history was a magnitude 9.
In the Yellowstone supervolcano complex in Wyoming, USA, and the Taupo volcano in northern New Zealand, there are giants that can turn the world upside down. As the bulk of the volcano, these huge volcanoes are usually "real people" and rarely "real". It may take tens of thousands or even hundreds of thousands of years for a supervolcano to accumulate a wave of "anger". It is also thanks to this that we do not have to be in constant fear in their shadows all the time.
Yellowstone Super Volcanoes
Even so, the existence of these giant volcanoes is still a sword of Damocles hanging over the head of the entire human civilization - once they wake up from their slumber, the entire earth's biosphere will face their terrible anger. I hope that people in the future can use the necessary technology and knowledge to defuse the threats of these big guys, rather than just helplessly praying that they will continue to be quiet.
