Volcanoes, Earthquakes, Tsunamis

Question 1

Intrusions

Answer 1

Magma cooling in a chamber below the ground

Question 2

Extrusions

Answer 2

Magma escaping the ground to the surface

Question 3

Pumice

Answer 3

Solidified bubbling magma

Question 4

Andesite

Answer 4

• Extrusive rock, formed by moderate viscosity lava

- Intermediate silica content caused by the partial melting of basalt in subduction zones

Question 5

Fumaroles

Answer 5

Fissures near active volcanoes that emit steam and volcanic gases

Question 6

Effusive/Hawaiian eruption

Answer 6

• Occur when hot, (1200oC) runny basalt magmas reach the surface
• Dissolved gases escape easily as the magma erupts, forming lava that flows downhill quite easily.
• Effusive eruptions build up gently-sloping Shield Volcanoes like Hawaii.

Question 7

Plinian Eruption

Answer 7

• Large explosive eruptions that form enormous dark columns of tephra and gas high into the stratosphere
• Named for Pliny the Younger, who carefully described the disastrous eruption of Vesuvius in 79 A.D.

Question 8

Strombolian eruption

Answer 8

• Volcanic eruption with relatively mild blasts
• VEI of 1-3
• Consist of ejection of incandescent cinders, lapilli, and lava bombs, to altitudes of tens to a few hundreds of metres

Question 9

Vulcanian eruption

Answer 9

• Volcanic eruption characterized by a dense cloud of ash-laden gas exploding from the crater and rising high above the peak
• Smaller than a Plinian eruption

Question 10

Peléan eruptions

Answer 10

• Viscous magma, typically of rhyolitic or andesitic type
• Presence of a pyroclastic flow
• Formation of lava domes, short flows of ash or creation of pumice cones may be observed as well

Question 11

Intermediate flows (Andesite)

Answer 11

• Composite cone
• 55% silica
• Quite vicious
• Partial melting of basalt in subduction

Question 12

Acidic/Felsic/Granitic flows

Answer 12

• 70% silica
• extremely vicious
• Usually doesn’t erupt and cools in magma chambers
• Partial melting of sediments dragged into subduction

Question 13

Supervolcanoes

Answer 13

Large granitic eruptions

Question 14

Ignimbrites

Answer 14

Rocks formed from pumice-dominated pyroclastic flow deposits

Question 15

Caldera

Answer 15

Large hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption

Question 16

Flood basalt

Answer 16

• Giant volcanic eruption/series of eruptions that covers large stretches of land/ocean floor with basalt lava
• Many flood basalts have been attributed to the onset of a hotspot reaching the surface

Question 17

Pillow lava

Answer 17

Pillow-shaped structures attributed to the extrusion of the lava underwater

Question 18

Basaltic lava flows

Answer 18

Hawaiian volcanism or undersea constructive volcanism

The least viscious eruption, highly liquid flows, non-explosive, forms shield volcanoes