Chapter 13

Question 1

how do igneous rocks form?

Answer 1

from magma or lava

Question 2

what do intrusive rocks crystallize from?

Answer 2

magma

Question 3

what do extrusive rocks crystallize from?

Answer 3

lava

Question 4

rhyolite

Answer 4

felsic igneous rock, explosive

Question 5

pumice

Answer 5

typically rhyolite with lots of holes

Question 6

andesite

Answer 6

intermediate igneous rock, explosive

Question 7

volcanic tuff

Answer 7

volcanic rock made of glass, ash, and rock fragments

Question 8

geologists monitor volcanoes using multiple approaches:

Answer 8

• seismicity: earthquake
• deformation: land surface movement
• sounds: infrared volcanic noise
• volcanic gas: fumaroles
• spring and river water temp and comp

Question 9

do volcanically triggered earthquakes have the potential to cause damage?

Answer 9

yes

Question 10

are volcanically triggered earthquakes usually smaller or bigger than earthquakes caused by non-volcanic sources

Answer 10

smaller

Question 11

are volcanically triggered earthquakes not always started by magma?

Answer 11

yes

Question 12

what could a volcanically triggered earthquake be triggered by?

Answer 12

mass of the volcano, groundwater movements, lahars

Question 13

swarms

Answer 13

cluster of earthquakes

Question 14

what are causes of lahars?

Answer 14

large rain fall, eruption that melts snow, dam break of a caldera lake

Question 15

what is the earliest sign of potential future eruption?

Answer 15

elevated gas emissions

Question 16

stratovolcano

Answer 16

• tall, conical volcano composed of one layer of hardened lava, tephra and volcanic ash
• rock types of typically felsic (higher in silica content)
• steep profile
• explosive eruptions
• cascade volcanoes