chapter 8 - Volcanoes

Most recent volcanic erruption

Kilauea 1983

How many categories during eruption are there?

three

Mount St Helens

the largest historic eruption in N America,

Kilauea

eruption began in 1983 and has been ongoing for more than 20 yrs

Magma

molten rock containing crystals and dissolved gases

lava

erupted lava

composition of magma

mafic, intermediate, felsic

magnic

problems of volcanic hazards

-              70 volcanic eruptions expected each year

-              One large-volume eruption each decade

-              500 million people live near active volcanoes

what are some of the volcanic hazards?

o   Pyroclastic flows

o   Lava flows

o   Lahars (mudflow)

o   Ash and volcanic gases

tsunamis (volcanic hazard)

caused by collapse of volcano flanks into the ocean

Ash (volcanic hazard)

can damage buildings, living things, aircraft engines

sulfur dioxide (volcanic hazard)

affects air quality and creates acid rain. (class example- France having a year with no summer)

atmospheric cooling (volcanic hazard)

ash and aerosols reflect solar energy

pyroclastic flows

hot volcanic gas infused incandescent ash and lava fragments. Low-density cloud of hot gases and fine ash on top of vesicular pyroclastic material.

Is gravity-driven and can move up to (60mph)

what are pyroclastic flows caused by?

collapse of eruption columns

Lahars

mudflows on active and inactive cones

Lahars are fluid ___

mudflows

Lahars are water-saturated volcanic debris move down ________

steep volcanic slopes

Lahars can occur on ________

dormant/extinct volcanoes

other volcanic landforms include:

calderas

creater lake-type caldera

collapse of the summit of a large composite volcano following an explosive eruption

Hawaiian-type caldera

form gradually due to the loss from a shallow magma chamber underlying a volcano’s summit

Yellowstone-type caldera

catasrophic eruption, tends to have a complex eruptive history, and is commonly referred to as supervolcanoes

fissure eruptions

emit basaltic lavas form fissures (fractures)

basalt plateaus

flat, broad accumulations of basalt emitted from fissures

flood basalts

molten lava having flowed long distanced within a basalt plateau

volcanic Necks (plugs) [volcanic hazard]

eroded cones expose the solidified magma inside the conduit

what is magma that crystalizes in Earth’s crust displacing host or country rock forms intrusions or plutons and is exposed by uplift and erosion, and classified according to shape ?

Intrusive Igneous Activity

Tabular or massive (shape classification of Intrusive Igneous activity)

may cut across existing structures or inject into parallel to features.