Despite sometimes giving out warning signs, volcanic eruptions are unpredictable. Even relatively less explosive ones can cause significant damage and fatalities, like the Nevado del Ruiz eruption in Colombia in 1985. Perhaps the most well-known deadly eruption is Mount Vesuvius in 79 A.D. It is estimated the catastrophe killed as many as 15,000 people. The volcano remains active. Currently, the most dangerous volcano on the planet is Aira in Japan.
Many volcanoes are located in what is known as the Ring of Fire. National Geographic defines it as “a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes. The majority of Earth’s volcanoes and earthquakes take place along the Ring of Fire.” (These are the most dangerous volcanoes in the United States.)
Officially, volcanoes are ruptures in the Earth’s crust, normally found where tectonic plates converge and diverge, that spew out lava, volcanic ash, and gasses. Many exist in the ocean.
Scientists have different ways of classifying types of volcanoes. A stratovolcano (or composite volcano) is a steep symmetrical cone built of lava flows, volcanic ash, and other materials (some of the world’s highest mountains are stratovolcanoes). A lava dome is a comparatively small volcano built from dense lava flow.
A caldera, considered particularly damaging to the surrounding environment, is a depression in the earth caused when the edges of the volcano collapse inward. A shield volcano is large and flat and composed almost entirely of lava flow. It is said to resemble a battle shield in shape. A pyroclastic shield is similar in form but formed mostly from rocks rather than fluid lava.
Not all volcanic eruptions are the same. Some are fairly calm and pose little threat to nearby inhabitants. Others can be violent, with catastrophic effects. Smaller volcanic events can be spectacular to witness from a safe distance and many active volcanoes release dazzling lava without massive violent eruptions. Others, though, continue to pose major threats to cities around the world, even if they’ve previously erupted. (These are the most devastating volcanic eruptions in history.)
To identify the most dangerous volcano on the planet, 24/7 Wall St. reviewed data from the National Museum of Natural History’s Global Volcanism Program. Each volcano on the list meets at least three of the following criteria: at least one major eruption, multiple large eruptions, high fatality eruption, frequent activity, or significant lava effusion. The explosiveness of volcanic eruptions are measured by the volcanic explosivity index. Mount Vesuvius eruption in 79 A.D. is believed to have had a volcanic explosivity index of 5.
The most dangerous volcano is Aira in Japan’s Kyushu island. It had a major eruption, multiple large eruptions, and a high fatality eruption. It has frequent activity with significant lava effusion. The city of Kagoshima is situated in the middle of the caldera and is home to over 900,000 people. Aira has several small eruptions every year. Aira has one of the most advanced seismologic monitoring systems in the world and residents are trained in evacuation procedures.
Click here to see the most dangerous volcanoes on the planet
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