Transcript Volcanoes-Earthquakes

PART 7: “VOLCANO EXPLORER” ACTIVITY
GLOBAL PERSPECTIVE
TECTONIC PLATES:
The Earth's crust is broken into
tectonic plates that fit together like a puzzle.
Most of the Earth's active volcanoes can be found
along these plate boundaries.
RING OF FIRE:
The Ring of Fire is one of the Earth's most
active volcanic zones.
It runs around the Pacific Ocean. On
the map below, show the area of the Ring of Fire.
LAYERS WITHIN
The plates, which make up Earth's
lithosphere, float on a semi-solid layer of molten rock
called the mantle or the asthenosphere.
The mantle has two layers:
(1) the upper mantle which is more solid and
(2) the lower mantle which is more liquid.
The lithospheric plates are constantly moving slowly,
colliding with or drifting away from each other.
Volcanoes form when this magma forces its way
through weak spots in the lithospheric plates.
This is most often at a plate
boundary (where two plates meet).
Volcano types
Inside a Volcano
The magma is relatively buoyant compared to the
surrounding rock because it is hotter, and hotter
things become less dense, causing them to rise above
the rest. This increased buoyancy causes it to rise
upward.
When pressures are great enough, the magma
ejects through the central vent and exits the volcano.
A dike is a region of magma that pushed out of
the magma chamber and solidified, but never
reached the surface.
Build your own volcano
Three factors affect the size
of the volcano and strength
of the eruption:
(1)Viscosity =
resistance to flow, or
“thickness” of the magma.
(2) Amount of Gas
(3) Amount of Silica
(the more silica,
the higher the viscosity!!)
CLICK THE VOLCANO For
Volcano Explorer!!
Generally, stronger eruptions are caused by __higher___
viscosity, __higher___ gas, & _higher_ silica.
PART 8: LITHOSPHERIC PLATE PUZZLE LAB
PART 9: VOLCANO & POMPEI VIDEOS
VOLCANO SITES
Virtual Volcano:
Crater Lake:
http://dsc.discovery.com/convergence/pompeii/interactive/interactive.html
http://planetoddity.com/wp-content/uploads/2010/03/crater-lake-1.jpg
Birth of an Island:
http://www.snopes.com/photos/natural/maiken.asp
Satellite Image of Eruption:
Iceland Eruption:
http://cimss.ssec.wisc.edu/goes/blog/archives/4513
http://www.youtube.com/watch?v=zXBER2uwepc
Mt. St. Helens Eruption Video (7 min):
http://www.youtube.com/watch?v=xP2dreOI8gI
Hawaii Volcano Video (4min):
http://video.nationalgeographic.com/video/environment/environment-natural-disasters/volcanoes/hawaii-volcanoes/
PART 10: EARTHQUAKE QUESTIONS &
EPICENTER ACTIVITY
FAULT: a break or crack along which rocks move
- Rocks on one side of the fault slide past the rocks
on the other side of the fault
- Movements can be up, down, or sideways
EARTHQUAKES
-Two blocks of rock form at a fault - one on top of the other
Hanging wall: the block of rock above the fault
Footwall: the block below the fault
Stress can cause either the
hanging wall or the footwall to
move up or down along a fault
See the Fault Line?
What wall is this?
What wall is this?
REVERSE
Hanging wall
moved UP relative
to the foot wall
NORMAL
Hanging wall moved
DOWN relative to
the foot wall
REVERSE
THRUST
Hanging wall
moved up and
OVER
TYPES
OFthe foot wall
PLATE
STRESSES
2 plates move
LATERAL
horizontally not
vertically
SAN ANDREAS
FAULT, CA.
8.2 Measuring Earthquakes
L-WAVES
 Move up and down like a water wave
 Slowest waves
 Travel at Earth’s surface
 Surface waves cause the most damage.
P-WAVES
- push (compress) and pull (expand) in the
direction that the waves travel
- Have the greatest velocity of all
earthquake waves
- Travel through solids, liquids, and gases
S-WAVES
- Shake particles at right angles
to the direction that they
travel (side to side movement)
- Travel only through solids
- Slower velocity than P-waves
R-Waves (Rayleigh waves)
TRIANGULATION
Seismic Waves
Why is it important to
study earthquakes?
They affect our lives
To better prepare for future earthquakes
(improve building technologies)
To gather information/data on where they occur,
how often, how intense.
Allow us to obtain information about the Earth’s
interior
Elastic Rebound Hypothesis
Measuring Earthquakes
 Seismographs are instruments that
record earthquake waves.
 Seismograms are traces of amplified,
electronically recorded ground motion
made by seismographs.
Measuring Earthquakes
1. Richter Scale (Outdated scale)
• Based on the amplitude of the largest seismic wave
• Does not estimate adequately the size of very
large earthquakes
2. Moment Magnitude
• Estimates energy released by an earthquake
• Derived from the amount of displacement that
occurs along the fault zone
• Measures very large earthquakes
LIQUIFACTION
Tilted Victorian home at
Howard and 17th Streets in the
Mission District of San
Francisco showing liquefactionrelated damage from the 1906
earthquake. This area is
underlain by marsh deposits
that were covered by artificial
fill in the middle to late 1800s.
The earthquake shaking caused
the artificial fill to liquefy and
lose its ability to support the
house.
(Photograph U.S. Geological
Survey)
TSUNAMIS
A tsunami triggered by an earthquake occurs
where a slab of the ocean floor is displaced
vertically along a fault.
LANDSLIDES
With many earthquakes, the greatest damage
to structures is from landslides and ground
subsidence, or the sinking of the ground triggered
by vibrations.
FIRE
In the San Francisco earthquake of 1906, most
of the destruction was caused by fires that started
when gas and electrical lines were cut.
PART 11:
TOPOGRAPHIC MAPPING
INDEX LINES
What is the contour interval?
20 ft
B
What is the contour
interval? 20 Feet
What is the highest point
on the map? 859 feet
What is the height at
point A? 780 feet
What is the height at
point B? 660 feet
A
What direction does
Equation Creek flow?
North
Is the slope of the land
greater under the
green line or the purple
line (lines are the same size!)
GREEN LINE