Transcript Volcanoes - Ms. Buzanowski's 8th Grade Class

Volcanoes
Chapter 8 Section 2
Pgs. 219 - 224
How volcanoes form
 Fissure
– crack in the crust, where a
conduit forms which acts like a pipe
magma travels through
 Magma is forced upward toward Earth’s
surface by denser surrounding rock
 Causes an eruption where magma,
solids, and gas are spewed out to form
cone-shaped mountains
 Lava
– magma flowing on Earth’s
surface through a vent or opening
 Craters – circular hole of volcano
 Tephra – bits of rock or solidified
lava dropping from the air
 Reservoir – where magma is stored
 Summit – highest point
 Vent - opening where lava flows
Where Plates Collide
 Volcanoes
form by a collision of large
plates of crust and upper mantle
 Oceanic
plate sinks under another
plate, rocks melt, forms chambers of
magma
Volcanic Risk Maps
 Used
to prepare people and visitors
about unsafe areas
Volcanic Eruptions
 Violent
or quiet
 Lava high in silica produces explosive
eruptions
 Lava high in iron and magnesium
produces more fluid eruptions
 The amount of water vapor and
gases impact eruptions
Shield Volcanoes
 Largest
type of volcano
 Gently sloping volcano that emits
mostly basaltic lava (very fluid) that
is long-lasting, gentle eruptions,
explosions minimal
Mauna Loa, HI
 Made
from 5 shield cones
 Largest volcano on Earth – Mauna
Loa in Hawaii, 6 miles tall
Cinder Cone Volcanoes
 Smallest
volcano, very steep with
large craters
 Formed
by moderate to explosive
eruptions of tephra
Cinder Cone Volcano
 Pu
‘ u ka Pele – Hawaii
 Mostly found on the sides of shield
volcanoes
Composite Volcano
 Steep
sides
 Formed
by alternating layers of
violent eruptions of tephra and
quieter eruptions of lava
Composite Volcano
 Most
active volcano – Mt. St. Helens
in the western part of the state of
Washington
Extreme Volcanoes
 Largest
volcano in the Solar System
– Olympus Mons on Mars, 17 miles
tall and over 320 miles across.
Questions
 Hawaii
is an example of what type of
volcano?
 What are the three types of material
that a volcano can emit?
 The eruption of Mount Vesuvius buried
what town in 79 A.D.?
 How did people die in the aftermath of
the famous Mount Vesuvius eruption?
 Mount St. Helen’s erupted violently in
1980. On what continent is this
volcano found?