


Parts of a volcano
Magma chamber
Neck
◦ Vent/crater


Cone/ash/lava
flow
Tephra/SO2/gases



Steep sided cone
Explosive eruptions
Lava type: tephra
◦ felsic
◦ Traps gases, thick


Example:
Paracutin Mexico
Plate bound – c/c

Rounded sides
◦ Dome


Quiet eruptions
Lava type: flows and
fountains
◦ Mafic – no granite, little
gases, flows readily


Example: Hawaii
Plate bound: o/o






Cone not as steep as a
cinder cone
Layers of tephra and
lava flow
felsic and mafic
Explosive and quiet
eruptions
Example: Mt. St.
Helens, Mt Ranier
Plate bound: o/c

Pahoehoe:
◦
◦
◦
◦
Quiet
Lava flow
Finger-like projections
Fast flowing like a river
Aa - A type
of lava having a
rough, jagged
surface.
 It is relatively slow
moving , thick
 in the form of
massive blocks
The blocks
size between the size
of a football and the
size of a house.


Pele’s hair
◦ Spun glass
◦ Made by fountains
◦ https://www.youtu
be.com/watch?v=O
EMyYNziXrc
◦
https://www.youtu
be.com/watch?v=Q
8NXO6YxBmU


Pele’s tears
Volcanic glass



A pyroclastic flow
a fast-moving
current of hot gas
and rock
(collectively known
as tephra),
speeds moving
away from a
volcano of up to
450 mph.
Felsic
Mafic
Temp
Low
High
SiO2 content
High > 70%
Low <50%
Volatile content
High 10% water
Low <2%
viscosity
High (very thick)
Low (very fluid)
Type volcano
Type lava
Type boundary
Dome/shield
Hawaii
Mafic
o/o
Hot spot
Cinder cone
Felsic
c/c
Mafic and Felsic
o/c
Vesuvius/Etna
Composite/Strato
Mt. St. Helen’s
Type of Eruption
quiet
explosive
quiet/explosive