Ch. 5 Notes (Volcanoes)

Question 1

Crater

Answer 1

steep-walled depression at the summit, generally less than 1 kilometer in diameter

Question 2

Caldera

Answer 2

a summit depression typically greater than 1 kilometer in diameter, produced by collapse following a massive eruption

Question 3

Vent:

Answer 3

opening connected to the magma chamber via a pipe

Question 4

Factors determining the “violence” or explosiveness of a volcanic eruption and also These three factors control the viscosity of a given magma

Answer 4

Composition of the magma
Temperature of the magma
Dissolved gases in the magma

Question 5

Viscosity

Answer 5

is a measure of a material’s resistance to flow (e.g., higher viscosity materials flow with greater difficulty)

Question 6

Factors affecting viscosity

Answer 6

Temperature: hotter magmas are less viscous
Composition: silica (SiO2) content
Higher silica content = higher viscosity

Question 7

aa Flow

Answer 7

blocky, crumbly, colder, slow doesn’t flow well, rolls overself

Question 8

Pahoehoe flow

Answer 8

flows like a liquid, smooth, hotter, ropy

Question 9

Lava Tubes

Answer 9

once served as conducts carrying lava from an active vent to the flow’s leading edge

Question 10

Pillow lava

Answer 10

form on ocean floor, resemble toothpaste coming out of the tube

Question 11

Ash and dust:

Answer 11

fine, glassy fragments

Question 12

Pumice:

Answer 12

porous rock from “frothy” lava

Question 13

Lapilli:

Answer 13

walnut-sized material

Question 14

Cinders:

Answer 14

pea-sized material

Question 15

Blocks:

Answer 15

hardened or cooled lava

Question 16

Bombs:

Answer 16

ejected as hot lava

Question 17

3 types of volcanoes

Answer 17

Shield- slightly domed, largest, mild eruptions (ex: Mauna Loa on Hawaii)
cinder cone- built from ejected lava, small in size (ex: Paricutin in Mexico)
composite/stratovolcano- most violent, produces pyroclastic (mt. st. Helens)

Question 18

Lahar

Answer 18

volcanic mudflow

Question 19

Pyroclastic Flows

Answer 19

Associated with felsic and intermediate magma

Consist of ash, pumice, and other fragmental debris

Question 20

Volcanic Hazards

Answer 20

Climate: ash and gases can cool the climate after an eruption
Fume hazards also present.

Question 21

Convergent volcanism

Answer 21

subduction zones
dehydration melting of mantle
water from subducting plate