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If the magma finds a path to the surface, then the result will be a volcanic eruption; consequently, many volcanoes are situated over magma chambers. [2] These chambers are hard to detect deep within the Earth, and therefore most of those known are close to the surface, commonly between 1 km and 10 km down. [3]
Volcanic earthquakes, or volcanic-tectonic earthquakes, can be caused by the movement of magma or other volcanic fluids, inducing tectonic stress that leads to earthquakes of high frequency. Lower frequency volcanic earthquakes, a result of resonation (physical oscillation from seismic waves) in cracks due to magma movement, may also be ...
Before and during volcanic eruptions, volatiles such as CO 2 and H 2 O partially leave the melt through a process known as exsolution. Magma with low water content becomes increasingly viscous. If massive exsolution occurs when magma heads upwards during a volcanic eruption, the resulting eruption is usually explosive. [104]
Eruption fears as magma spreads underground and cracks appear in roads. ... Volcanic eruption could ‘bury’ evacuated town, says geologist ... “The closure will remain in effect until 7am on ...
Strombolian eruptions are a type of volcanic eruption named after the volcano Stromboli, which has been erupting nearly continuously for centuries. [13] Strombolian eruptions are driven by the bursting of gas bubbles within the magma. These gas bubbles within the magma accumulate and coalesce into large bubbles, called gas slugs.
In explosive volcanic eruptions, the sudden release of gases from magma may cause rapid movements of the molten rock. When the magma encounters water, seawater, lake water or groundwater, it can be rapidly fragmented. The rapid expansion of gases is the driving mechanism of most explosive volcanic eruptions.
A volcanic eruption is essentially the only natural way for short-lived – less than a few years – gases like sulfur dioxide and water vapor to make it into the stratosphere.
The Grímsvötn volcano in Iceland is a sub-glacial volcano, located beneath the Vatnajökull ice cap. For a typical sub-glacial eruption, overlying glacial ice is melted by the heat of the volcano below, and the subsequent introduction of meltwater to the volcanic system results in a phreatomagmatic explosion. [12]