Transcript Volcanoes 3 typesx

Let’s look at two more examples of stratovolcanoes
(also known as composite cones).
Krakatoa
Mount St. Helens
subduction zones.
Both of these volcanoes are found at _____________
On August 27th, 1883
a series of blasts on
the island of Krakatoa
culminated in a
colossal explosion
that blew the island
apart in one of the
largest eruptions in
recorded history.
Krakatoa
video
• Four enormous explosions throughout the day of August 27
• The third eruption was the loudest sound in recorded history
(heard 3,000 miles away!)
• Large tsunamis accompanied each explosion
(reports of over 100 ft.)
• Pyroclastic debris scattered throughout the Indonesian
islands, and ash spouted over 80 km in the air
• Shockwave reverberated around the entire planet 7 times
• Earth’s overall climate cooled by a few degrees for the next
year after the eruption
• Death toll estimates as high as 120,000
…and just this year 
typical composite volcano
Caldera formed
by the eruption
•
•
•
•
Subduction zone
Rising magma
Felsic, high viscosity
Explosive, composite
cone (stratovolcano)
YouTube clip
Remember, most volcanic
activity is non-explosive.
Which of these three types gets the biggest, by far?
Shield volcano
Stratovolcano
Cinder cone
Shield Volcano
Broad, large,
dome shaped,
non-explosive
Cinder cone
Composite cone
(stratovolcano)
 Show Ms. Ehly your completed lesson and Some Goes
Pop worksheet
 Get a Virtual Volcano worksheet and go to the next
slide.
Minerals:
• mineral
• crystalline structure
• silicate/non-silicate
• luster
• streak
• cleavage/fracture
• hardness
• density
The Rock Cycle:
• rock
• rock cycle
• weathering
• erosion
The Rock Cycle (cont.):
• deposition
• texture
• composition
• igneous
• sedimentary
• metamorphic
• intrusive/extrusive
• mafic/felsic
• stratification
• cementation
• foliated/non-foliated
Plate Tectonics:
• crust
• mantle
• inner/outer core
• lithosphere
• asthenosphere
• mesosphere
• tectonic plates
• continental drift
• seafloor spreading
• mid-ocean ridge
• magnetic reversal
• subduction
• trench
• convergent
• divergent
• transform
Earthquakes:
• seismograph
• P waves
• S waves
• epicenter
• focus
• magnitude
• Richter/Mercalli
Volcanoes:
•cinder cone
• composite (strato) volcano
• shield volcano
•viscosity
• explosive/non-explosive
• hot spot volcano
Homework:
Study for test 12/1