What do explosive volcanic eruptions result from?
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent.
What makes a volcano a supervolcano?
The term “supervolcano” implies a volcanic center that has had an eruption of magnitude 8 on the Volcano Explosivity Index (VEI), meaning that at one point in time it erupted more than 1,000 cubic kilometers (240 cubic miles) of material.
Why are super volcanoes so explosive?
Possible triggers for explosive eruptions include (1) gas saturation in crystalliz- ing magma (volatiles are partitioned into remaining liquid); (2) replenishment by fresh drafts of magma; (3) escape of gas-rich, crystal-poor magma from crystal mush and storage of this low-density, low-strength magma beneath the cham- …
Which type of volcanic eruption is very explosive?
Phreatic eruptions pulverise surrounding rocks and can produce ash, but do not include new magma. An eruption resulting from the interaction of new magma or lava with water and can be very explosive.
What do super volcanoes do?
A supervolcano is any volcano capable of producing a volcanic eruption with an ejecta volume greater than 1,000 km3 (240 cu mi). This is thousands of times larger than normal volcanic eruptions. Supervolcanoes are on a much bigger scale than other volcanoes.
What are the 3 stages of a supervolcano?
Supervolcanoes
- it erupts at least 1,000 km 3 of material (a large volcano erupts around 1 km 3)
- it forms a depression, called a caldera (a volcano forms a cone shape)
- a supervolcano often has a ridge of higher land around it.
- a supervolcano erupts less frequently – eruptions are hundreds of thousands of years apart.
What is it about Supervolcanoes that make them so super?
Supervolcanic Fuel For a volcano to be called “super,” it has to have the potential to eject more than 1000 cubic kilometers, or 240 cubic miles, of volcanic material. That is one thousand times greater than any volcanic eruption seen by modern humans.
What is the composition of supervolcano eruptions Why are these eruptions so massive?
The exact cause of supervolcano eruptions is still debated. However, scientists think that a very large magma chamber erupts entirely in one catastrophic explosion. This creates a caldera into which the surface collapses (Figure below). The composition of the eruption is felsic or highly felsic.
What kind of volcanic eruption is least explosive?
Shield volcanoes
Shield volcanoes tend to be the least explosive volcanoes.
Which is the most explosive type of volcanic eruption Why?
Plinian Eruption The largest and most violent of all the types of volcanic eruptions are Plinian eruptions. They are caused by the fragmentation of gassy magma, and are usually associated with very viscous magmas (dacite and rhyolite).
Which is an example of an explosive eruption?
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent.
Are there any volcanoes that can produce a super eruption?
Additional volcanoes capable of producing supereruptions include the large caldera volcanoes of Japan, Indonesia, and South America. Until now, it had been widely thought that the likelihood of a blow-out was dependent on the presence of liquid magma under a volcano.
How big is the largest volcanic eruption on Earth?
Every now and again Earth experiences tremendous explosive volcanic eruptions, considerably bigger than the largest witnessed in historic times. Those yielding more than 450 km 3 of magma have been called super-eruptions.
How does an eruption of a volcano affect the Earth?
Volcanic eruptions are among Earth’s most dramatic and powerful agents of change. Ash, mudflows, and lava flows can devastate communities near volcanoes and cause havoc in areas far downwind, downstream, and downslope. Even when a volcano is quiet, steep volcanic slopes can collapse to become landslides, and large rocks can be hurled by powerful…