Definitions
Magma
molten rock (has crystals & gases within it) (intrusive)
how many volcanoes and eruptive types are there
Six volcanoes and eruptive types
what are the two Volcanoes hazard classification
Explosive / non-explosive
what is Nuee ardente
gas cloud of great heat, and turbulence
(very small). Forms as it sounds, build up of lava that spatters from the vent.
Spatter cones
magma that reaches the earth’s surface (extrusive)
Lava:
name three volcanoes and eruptive types
Flood basalt, Shield volcanoes, Cinder cones, Composite cones or Stratovolcanoes, Caldera,
Others (Lava Domes, Spatter cones, Volcanic plugs)
Non-explosive
low viscosity magma & low amount of dissolved-gas (e.g. basaltic lavas). But: cooling lava may trap some gas bubbles - creating vesicles (vesicular texture)
volcanic debris flow(hot ‘mud’ flows); a particular hazard when volcanoes are ice/snow capped
Lahar
Volcanic plugs are?
when lava cools and plugs the vent
Volcano
a vent from which magma, gases and solids are ejected, can build up to form a mt-like shape but not necessary!
Very fluid lava, ejected from a fissure (crack) the low viscosity lava floods over the land. Often these features are fed from mantle plumes.
Flood basalt
Explosive
moderate to to high-viscosity magma and higher amounts of dissolved-gas (e.g. andesitic & rhyolitic lavas). As magmas slowly rise through the lithosphere, they allow time for the gas to expand. The higher the viscosity; the greater the prospect of an explosive eruption
what are the hazards of Lava Flow
loss of life but more likely loss of property, vegetation. (Note destruction and blocking of the road by the lava flow on Hawaii Island.)
what volcano is this describing
Lava flows quickly and over great distances, appearing like lava rivers down the volcano slopes and when cooled can leave lava tubes through which common. Some damage to infrastructure, not usually associated with loss of life.
Shield volcanoes
Pyroclastic material:
solid rock fragments ejected during an eruption.
largest volcanoes found on Earth are?
Shield volcanoes are the largest volcanoes found on Earth.
name five hazards
Tsunamis, Lava Flow, Lahar, Pyroclastic flow, Nuee ardente, Fumarole, acid rain, Eruption Cloud, Ash Fall,Eruption column , Eruptive blast, Earthquakes
what is Pyroclastic flow
‘avalanche’ of hot gas and pyroclastic material.
A volcanic crater that develops from the explosion and collapse of a composite volcano
Caldera
Air-borne pyroclastic material. Tephra is initially unconsolidated.
Tephra
Lava Domes
lava too viscous to flow and piles up at vent. Cools quickly glassy high silica obsidians.
what is Fumarole?
vents that emit hot gases, can be 1000ºC. Poisonous gases: (e.g. Vesuvius?) Gases such a CO2 and H2S are invisible, but highly toxic. Also liquid acids Sulphur contributes to acid precipitation (rain).
Why is ash fall dangerous
ash coats everything! If the ash is acidic (respiratory problems), fouling of engines, destruction of vegetation etc
what volcanos are Most commonly made of andesitic lava
Composite cones or Stratovolcanoes