So now that you have the basics down, it’s important to know that not all volcanoes are created equal. Each has their own distinct personality. There are some big mamma jamma’s out there. There are some with raging tempers and others that are a little more chill about life. Here is the rundown on who you might meet out there:
Shield volcanoes get their name from the very gradual grade of their slopes. In fact, the volcanoes look like a round warrior shield that is lying on the ground. These volcanoes are built almost entirely from fluid lava flows, usually basalt, which flows farther than other types of lava.
Examples: Mauna Loa, Kilauea, Erta Ale
Composite Volcanoes (Stratovolcanoes)
Composite volcanoes are tall, conical volcanoes that stand out from the landscape around them. They are built from repeated explosive eruptions of dacite, rhyolite and andesite. Layers of volcanic ash, pyroclasts, and lava build up over time to form these magnificent peaks. These volcanoes usually are found at plate boundaries and subduction zones.
Examples: Mt. Fuji, Mt. Rainer, Mayon Volcano
These are areas near a volcanic vent that eject loose materials such as hot cinders. These conical mountains, usually smaller than other volcanoes, are built almost entirely of cinders and ash, with occasional lava flows.
Examples: Paricutin, Sunset Crater
Flood Basalts & Large Igneous Provinces
All of the flood basalts on Earth happened before anyone was around to witness them, yet we can see their aftermath today. Massive amounts of basalt flooded out of the Earth and spread across the crust. These eruptions had major effects on the Earth’s climate and atmosphere, and some are even tied to extinction events. The closest thing that anyone has ever experienced to this is the eruption of Laki in Iceland in 1783.
Examples: Columbia River Basalt, Deccan Traps
There has been some debate on the use of this term, but it is a phrase that was coined with the general public to describe a volcano with the history of creating incredibly large and powerful volcanic eruptions. This is the type of eruption that will knock your socks off – and those within a thousand mile radius. An eruption of this size would certainly impact the climate and atmosphere around the globe for decades.
Like flood basalts, a supervolcano eruption hasn’t happened within the historical record. But we can see their footprints and some are even still breathing. The calderas left behind by these volcanoes are huge. Ash deposits from these eruptions can be found in distinct layers around the world. Some of these eruptions are also associated with extinction events.
Some are long extinct and haven’t so much as snored in the past million years. However, supervolcanoes such as Yellowstone and Campi Flegrei are still active. You can see the active hydrothermal systems in the form of geysers and fumaroles at these sites, and earthquakes are common. Will any of these blow sky high in our lifetime? You never know. Nature loves tossing curveballs. But as they haven’t gone off in the history of mankind, we’ll probably live to see another day. This is just a reminder of what a powerful world lies just beneath our feet.
Examples: Yellowstone, Toba, Campi Flegrei, Taupo
These eruptions are charactarized by runny basalt that flows down the slopes of the volcano. Occasionally fountaining may occur with this type of eruption.
Examples: Kilauea, Mauna Loa, Mauna Kea, Haleakala
Plinian eruptions are rich in silica and dissolved gasses, which makes them particularly explosive. They usually involve a combination of dacite and rhyolite, which makes things even stickier. These eruptions usually produce enormous columns of ash that shoot high into the atmosphere. These eruptions can last from hours to days.
Examples: Vesuvius, Mt. St. Helens
Occasionally a volcano will explode and emit a pyroclastic flow that is full of ignimbrites that it leaves behind in a sheet that resembles a lava flow. Ignimbrite is a mixture of volcanic ash (sometimes tuff) and pumice. Sometimes the heat of these flows is so intense that it actually causes the rock to weld together. These are usually composed of dacite and rhyolite, with occasional volcanic glass mixed in.
These flows often cover thousands of square kilometers and can completely fill in valleys and alter landscapes. They are common near large volcanic provinces.
Examples: Taupo Volcanic Zone
These eruptions usually consist of basalt and are short in duration and short in repose. That means that eruptions can last from a few seconds to a few minutes and then shut off. The volcano will rest for a few seconds to several minutes, catching its breath, and then will start up again with another eruption. The sequences do not eject a lot of volume and are fairly week. What they do eject usually has a ballistic trajectory.
Sorry to disappoint, but this is not the volcanic eruptions that take place on planet Vulcan. These eruptions are similar to strombolian eruptions but are usually caused by a combination of basalt, andesite and sometimes dacite. These mixtures can create an extremely violent eruption. Live long and prosper!
Example: Mt. Pelée
These eruptions happen when magma and water collide and are usually explosive. They can form some impressive tephra jets, or cockstail plumes, when they occur.
Example: They usually happen at the midoceanic ridges, or in Iceland and Hawaii when hot lava collides with water.
These are low volcanic craters with attached volcanic pipes that cut deep into the rock beneath them. These volcanoes are formed by intense gas explosions. When there is a crack in the crust of the Earth, it allows heated magma to rise up into it. When this magma collides with groundwater, the sudden evaporation of gasses can lead to a series of violent explosions. These are usually associated with a type of magma called kimberlites, and diamonds can often be found near these volcanoes due to their composition.
Examples: Ukinrek Maars
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