An explosive eruption is a volcanic term to describe a violent, explosive type of eruption. Mount St. Helens in 1980 was a good example of an explosive eruption. Such an eruption is driven by gas including water vapour accumulating under great pressure. Driven by the hot rising magma as it interacts with the ground water the pressure increases until it bursts violently through the overmantle of rock. This is merely the beginning. In many cases the rising magma will have vast quantities of gas dispersed through it, partially dissolved; held only by the enormous pressure. With the sudden release of pressure following the initial explosion this gas resumes its gaseous form, violently and explosively. This secondary explosion is often far more violent than the first one; the rocks, dust, gas and pyroclastic material may be blown 20 km into the atmosphere at rate of up to 100,000 tonnes per second, travelling at several hundred metres per second. This article is about volcanoes in geology. ... Mount St. ... 1980 (MCMLXXX) was a leap year starting on Tuesday. ... Boundaries: Phase, Pressure, Temperature Evaporation/Sublimation Whenever a water molecule leaves a surface, it is said to have evaporated. ... Magma is molten rock located beneath the surface of the Earth (or any other rocky planet), and which often collects in a magma chamber. ... Groundwater is any water found below the land surface. ... Pyroclastic rocks are formed from lavas which are ejected into the air, as occur in pyroclastic flows or Plinian eruptions. ...
Sooner or later this cloud collapses, almost as violently, creating a pyroclastic flow, the killer cloud of hot volcanic matter. Pyroclastic flows sweep down the flanks of Mayon Volcano, Philippines, in 1984 Pyroclastic flows are a common and devastating result of some volcanic eruptions. ...
See also effusive eruptions, the gentler kind of volcano. Effusive eruptions are a volcanic phenomenom; in some ways the opposite of explosive eruptions. ...
Sub-marine landslides (which are sometimes triggered by large earthquakes) as well as collapses of volcanic edifices may also disturb the overlying water column as sediment and rocks slide downslope and are redistributed across the sea floor.
Waves are formed as the displaced water mass moves under the influence of gravity and radiate across the ocean like ripples on a pond.
This was in part due to the absence of major tsunami events between 1883 (the Krakatoa eruption, which killed 36,000 people) and 2004.
A lateral eruption may occur if an eruption is released sideways: for example, by a vent that is not in the center of the crater; by a landslide from one side of the crater (as at Mt. St.
Obviously, lateral eruptions tend to be destructive mainly in one direction, whereas the collapse of a vertical eruption may be destructive all round the base of the volcano.
Helens eruption were professionals doing their jobs in hazardous conditions (geologists and forestry workers), residents who refused to evacuate, and ignorant or reckless individuals who ignored the warnings of scientists and government officials at various levels.
Feeds |
Contact