Chapter 4

Question 1

Viscosity

Answer 1

Substance’s resistance to flow. Directly linked to silica content.

Question 2

Factors affecting viscosity

Answer 2

Increasing silica content (increase), increasing temperature (decrease), loss of volatiles, crystallinity, bubble content, shear stress

Question 3

Mafic lava

Answer 3

Can flow a significant distance from the vent (low viscosity), creates pillows underwater.

Question 4

Intermediate lava

Answer 4

Covers less distance than mafic lava.

Question 5

Felsic lava

Answer 5

Creates obsidian, much more viscose.

Question 6

Volcanic ash expelled during an eruption

Answer 6

Less than 2mm, pyroclastic

Question 7

Lapilli expelled during an eruption

Answer 7

2-64mm, pyroclastic

Question 8

Bombs/blocks expelled during an eruption

Answer 8

Greater than 64mm, pyroclastic

Question 9

Lahars

Answer 9

Volcanic mud/debris flow expelled with or without an eruption

Question 10

Volcano Explosivity Index (VEI)

Answer 10

Measures eruption size by volume of material ejected and height of eruption column.

Question 11

Shield volcanos

Answer 11

Formed by mafic lavas, gentle slopes with a caldera that forms a summit.

Question 12

Cinder/scoria Cone volcanos

Answer 12

Formed by one eruptive episode and considered monogenetic

Question 13

Composite/Stratovolcanoes

Answer 13

Alternating layers of ash and lava with a steeper slope due to more viscous lava. Symmetric, young, and unstable.

Question 14

Calderas

Answer 14

Form towards the end of the lifecycle of an arc volcano

Question 15

Divergent boundaries (ch. 4)

Answer 15

Volcanoes found in rifts and in mid-ocean ridges

Question 16

Convergent boundaries (ch. 4)

Answer 16

Have many volcanoes found in subduction zones

Question 17

Transform Boundaries (ch. 4)

Answer 17

Don’t have many volcanoes, instead have earthquakes.