Different Types Of Volcanoes

Question 1

explosive eruptions

Answer 1

found in: convergent plate boundaries
type of lava: rhyolite

acidic, high viscosity, lower temp at eruption

style of eruption: violent bursting of gas bubbles when magma reaches surface; highly explosive

materials erupted: gas, dust, ash, lava, tephra bombs

freq of eruption: tend to have long periods with no activity

steep sided stratovolcano

eg Pavlof, Alaska
eg Lewotolo, Indonesia

Question 2

strato volcano

Answer 2

known as composite cone volcano, made up of layers of ash and acid lava, have concave symmetrical profiles

because acid magma does not flow easily, the vents are often filled with a mass of solidified magma. enormous pressures can build up inside a volcano until eventually it erupts explosively

Question 3

effusive eruption

Answer 3

found in: divergent plate boundaries
type of lava: basalt

basic, low viscosity, higher temp at eruption

style of eruption: gas bubbles expand freely; limited explosive force
material erupted: gas, lava flows

freq: tend to be more freq, can continue for many months

shield volcanoes with gently sloping sides

eg Grimsvoth, Iceland
eg Soufrierè, St. Vincent

Question 4

super-volcanoes

Answer 4

erupts more than 1000km2 of material, exists as giant caldera, eruption of 8 magnitude on VEI eg Yellow stone

Question 5

caldera

Answer 5

volcanic craters, usually more than 2km in diameter. develop when an explosive eruption destroys much of the cone

eg 1883 eruption of Krakatoa, Indonesia left a 7km wide caldera

Question 6

what products are produced by effusive eruptions?

Answer 6

lava plateaux - basic magma erupts from multiple fissures, vast areas can be covered by free flowing lava (flood basalts) eg Deccan Plateau in central India

shield volcanoes - found at divergent boundaries, eruptions of basic lava = in gently sloping sides

Question 7

hot spot

Answer 7

a fixed area of intense volcanic activity where magma from a rising mantle plume (hot plumes ruse upward, forming volcanoes on overlying crust) reaches the Earth’s surface. eg Hawaiian Emperor chain of volcanic islands (as pacific plate has moved slowly NW over the Hawaiian hotspot, vast amounts of basalt have accumulated to produce Hawaiian islands)

Question 8

how are hotspots formed?

Answer 8

when a plume rises into shallow mantles, it melts + may then rise to the surface where it can erupt as hot spot volcano

mantle plumes are thought to be stationary where as overlying tectonic plates typically are not -> as a plate moves over location of plume eruption it carries older volcanoes with it

Question 9

Icelandic lava eruption

Answer 9

persistent fissure eruption, large quantity of basaltic lava build up eg Deccan Plateau

Question 10

Hawaiian eruption

Answer 10

noticeable, central activity. runny, basaltic lava travels down sides of volcano

Question 11

Strombolian eruption

Answer 11

freq gas explosion which blast runny lava into the air to form cones. very explosive, white clouds of steam

Question 12

Vulcanian eruption

Answer 12

violent gas explosions blast out plugs of sticky lava, occur when there is viscous lava which solidifies rapidly after explosion

Question 13

Versuvian eruption

Answer 13

very powerful blasts of gas pushing ash cloys into sky

more violent than Vulcanian

Question 14

Plinian eruption

Answer 14

violent explosions, immense clouds of gas + volcanic debris several km thick. huge explosion