Notes Chapter 13 Volcanoes
Section 13.1 – Volcanoes and Plate tectonics
Formation of magma

___________________ rock produced ________________ Earth's surface

forms when ____________________ high enough and ____________________ low
enough to melt rock, or when ___________________ (like water)are _______________
and decrease the melting point

called __________ when it reaches the surface

_______________________ - any activity that moves magma to the Earth's surface
major volcanic zones

_____________________
 Encircles the ____________________________
 Made up of ________________________ zones
 Also a major _______________________________

Subduction Zones

oceanic-continental denser _____________________ plate subducts
o
deep ________________ forms
o
as plate subducts, salt water is added reducing the __________________
point and magma forms
o

forms _____________________________________ as magma erupts on surface
oceanic-oceanic
o same as oceanic continental, but forms an __________________ instead

Mid-Ocean Ridges
o produces the ________________________
o as plates pull apart, magma rises and adds new material to the ridge
(___________________________)
o salt water rapidly ___________ the lava and creates
__________________
o most ______________________ go unnoticed


Hot Spots
o areas of volcanic activity in the ________________________________ plate
(not at a boundary)
 forms from _________________________ (columns of solid, hot material) or
cracks in Earth's crust
 forms __________________ islands
 __________________ are stationary
 as the plate continues to move, the volcanic activity
_______________________________because it is no longer over the hot
spot
Section 13.2 – Volcanic eruptions
Types of eruptions

Volcanic Eruptions
 ____________________ - vent (opening) in Earth's surface
through magma
and gases are expelled
 ______________________ - measure of a material's resistance to flow
o
thicker material, greater viscosity
affected by temperature, silica
content, and dissolved gases
 ________________________________
 factors that determine the ______________________of eruption

o
________________________ of magma
o
________________________ of magma
o
dissolved _________________ in magma
Types of Magma
 _______________
o
low in silica
o
thin
o
dark in color
o
rapid movement
o
dissolved gases escape easily
o
smooth-flowing eruptions
o
creates broad-based volcanoes
 _____________________
o
high in silica thick
o
light in color
o
slow movement
o
dissolved gases do not easily escape
o
explosive eruptions
o
creates steep-sided volcanoes
Materials Associated with Volcanic Eruptions

____________ flows
 ______________________ lava - looks like ____________
 _______ lava - jagged _____________________
 ______________________ lava - large chunks ·

_______________
 water vapor, carbon dioxide, sulfur, hydrogen, chlorine
 pyroclastics - "fire fragments"

_____________________________________________________________(increasing in size)
Types of Volcanoes

__________________
 broad base w/gentle sloping sides
 ___________________ eruptions of mafic lava
 ex. Hawaiian Islands

___________________
 steep sloping sides
 ________________________ eruptions w/large pyroclastics

______________________________________________
 form large volcanic mountains
 ______________________________ between quiet and explosive eruptions
 most violent eruptions
 ____________________________ found in Pacific Ring of Fire
Calderas

like a _________________________

magma chamber below a volcano empties and the cone ______________ inward

may ________________________________ and form lakes
Predicting Volcanic Activity

_________ reliable way

methods of prediction
 _________________ in earthquake ______________________ around volcano
 ____________________ - areas of magma pushing against volcano

volcano's _____________________________