Volcanoes

Question 1

what is a volcano?

Answer 1

a hole in the ground

Question 2

what is the mountain etifis?

Answer 2

the mountain

Question 3

where do we find volcanoes?

Answer 3

• pacific ring of fire
• subduction zones: hydrated magma

Question 4

why do ocean ridges cause volcanoes?

Question 5

What are hot spots?

Answer 5

burns through lithosphere
but lithosphere moves
chain islands
primitive
deep mantle
high He/Ne isotope ratio

Question 6

how is volcanism associated with plate tectonics?

Question 7

volcanoes and convergent plates

Question 8

what controls the composition and nature of an eruption?

Answer 8

where the volcanoes are located

Question 9

what are refractory elements?

Answer 9

everything that isn’t silica

Question 10

how does silica determine magma type, extrusive rock, and instrusive rocks?

Answer 10

weight percent

Question 11

how does water affect magma?

Answer 11

lowers melting temperature

Question 12

what are flood basalts?

Answer 12

• monstrous eruptions
• volumetric
• a lot of rocks melted and came up

Question 13

what are shield volcanoes?

Answer 13

low slope
broad
fluid basalt
can run down a shallow hill

Answer 14

lava viscosity

Question 15

what are cinder cones?

Answer 15

• pieces spit out that pile-up and get steep
• by the time they hit the ground they are hard

Question 16

what is the angle of repose?

Question 17

stratovolcanoes

Answer 17

-stratified
- composed a different in nature magma
- spatter, ash,
- very steep

Question 18

volcanic dome

Answer 18

• viscous
• cool
• close to solidus
• comes out and solidifies right away

Question 19

caldera

Answer 19

what is left after a very explosive eruption
- magma chamber comes out of the ground
-a hole in the ground that subsides

Answer 20

controls style of eruption

Question 21

effusive

Answer 21

molten magma oozing out and flowing

Question 22

explosive

Answer 22

viscous magma fragments and shoots into the air

Question 23

pahoehoe

Answer 23

move quickly
- slower than a walk

Question 24

Aa

Answer 24

the same stuff as pahoehoe but breaks up
- more force
- steep
- past stress
- little bit faster

Question 25

what does flow type depend on?

Answer 25

rheology and strain rate

Question 26

fissure eruptions

Answer 26

crack in the ground erupt basalt flood basalts hexagonal

Question 27

flood basalts

Question 28

light rare earth enrichment

Answer 28

La/Sm ratio tell us primitive source melt - minerals don't want -first thing to go into melt

Question 29

Capatability

Answer 29

isotope ratios

Question 30

where do hot spots come from?

Answer 30

whole or layered mantle convection

Question 31

scoria cone

Answer 31

- cinder - steep

Question 32

composite cones

Answer 32

- stratovolcanoes - pyroclastic (fire particles) - bigger than cinder

Question 33

volcano influence on atmosphere

Answer 33

ash and water vapor

Question 34

why do they erupt

Answer 34

- bubbles of gas in magma -

Question 35

plutonic

Question 36

what kind of relationship does viscosity have with water diffusivity?

Answer 36

inverse

Question 38

surtseyan explosion

Answer 38

water explosion chills and breaks up small

Question 39

plinian explosion

Answer 39

sustained, fire hydrant

Question 40

strombolian explosion

Answer 40

pop gun

Question 41

vulcanian explosion

Answer 41

kaboom

Question 42

how do we measure explosivity?

Answer 42

VEI: volume of tephra (stuff that comes out of the ground, hard to do)

Question 43

Simplified VEI

Question 44

what comes out of volcanoes?

Answer 44

basalt andesite

Question 45

what size is ash?

Answer 45

less than 2 mm

Question 46

what size is lapilli

Answer 46

2-64 mm

Question 47

what sizes are blocks and bombs?

Answer 47

more than 64 mm - surface tension irrelevant

Question 48

what is tephra?

Question 49

what is tuff?

Question 50

PDC

Answer 50

hundreds of km/hr large particles dragged down by air, dense deadly