Name:___________________________________________
Date:_________________
Chapter 11 High Ability Test is Wednesday, February 18th!
Boundaries, Fault Blocks, and Earthquakes:
Pages 373-378
1. Describe a normal fault using the words tension, hanging wall and divergent boundary.
A normal fault is a break in the Earth
where tension pulls rock apart, creating
a divergent boundary. The hanging wall
falls below the footwall at the normal
fault.
2. Describe a reverse fault and include the force and boundary type.
A reverse fault is a break in the Earth
where compression pushes rock
together, creating a convergent
boundary. The hanging wall can rise up
and over the footwall at a reverse fault.
3. Describe a strike slip fault and include the force and boundary type.
A strike-slip fault uses shearing forces
to create a transform boundary.
There is no up and down motion,
instead the rock moves side to side.
4. Describe how folded mountains form using the correct boundary type and give two examples of
folded mountains around the world.
Folded mountains occur due to
compression at a convergent boundary.
Examples might be the Himalayas and
the Alps. Drakensburg Mountains
5. Describe how fault block mountains form using the correct boundary type and give two
examples of fault block mountains around the world.
Fault Block Mountains occur due to
tension at a divergent boundary.
Examples might be the Great Basin
Valley and the Grand Tetons.
6. Describe the motion of p-waves, s-waves, and surface waves and in what order they travel
through the Earth. Be able to label these waves on a pretend seismogram. See page 390.
The p-waves travel out first and
compress and expand the Earth like an
accordion. The s-waves come second
and move the Earth side to side. The
surface waves are a combination of both
p and s waves and they move in a
circular pattern.
7. Explain the difference between the Modified Mercalli Scale and the Richter Scale.
The modified Mercalli scale uses roman
numerals (I-VIII) to rank the shaking and
damage on the surface of the Earth. This
scale is based on human observations.
The Richter scale is an Arabic number
scale (1-14) that measures the energy
and the magnitude of the quake mostly
due to the seismograph data.
8. Explain how geologists locate an epicenter. In your description, you must include the use of the
distance vs. time graph and the use of the s-p lag time as well as the mapping of the epicenter
using triangulation of the radii of 3 or more circles.
First the scientist measures the s-p lag time
from the seismograph. Since the speed of
the earthquake is a known value, then
distance of the seismograph from the quake
can be calculated using time and speed.
The distance is plotted on a map using 3 or
more seismographs, with the radii of the
circles being the distance. The point of
overlap of the circles’ circumference is the
epicenter of the quake.
9. What is the difference in the focus and the epicenter?
The focus is the area beneath the
surface where the rock under stress
begins to move. The epicenter is the
point above the focus on the surface,
where the energy is the greatest.
Volcanoes:
10. What are the three ways (places) in which volcanoes can form?
See notes in
the journal
1. Converging boundaries can form
where subduction is forming
volcanoes (island arcs) at deep-
ocean trenches or at the border of
oceans and continents.
2. Diverging boundaries can form
volcanoes mid-ocean ridges in the
ocean or at rift valleys on land.
3. Hot spots can occur over ocean or
continental crust.
11. Define the terms:
a.
The boundary around the
Pacific plate, where volcanoes and
earthquakes are common.
Ring of Fire…
A weak place where magma can
rise up into the crust from the
mantle.
b. Hot spot…
c.
Both are the molten (liquid)
rock but the magma is below the
surface and lava has reached the
surface of earth.
Lava vs magma…
d.
A hole or crater in the volcano
after material has collapsed in after
an eruption.
Caldera…
e.
Extinct volcanoes are
dead and will no longer erupt; while
dormant volcanoes may be asleep
but have the potential to erupt
again.
Extinct vs. dormant…
f.
A steep hill or small
mountain made from pyroclastic
Cinder cone volcano…
flow (ash, rock) but no lava; These
are the more explosive volcanoes
and can have a higher silica content.
g.
A tall mountain made
from alternating layers of lava and
solid rock or ash; Mt. St. Helens is a
good example.
Composite volcano…
h.
Hawaiian Island volcanoes
are good examples of shield
volcanoes. These are broad, flat
and are made entirely of oozing
lava. These volcanoes have low
silica content.
Shield volcano…
This is material that is made
of gas, ash, cinders, or bombs
during an explosive eruption.
i.
Pyroclastic flow…
j.
Island arc…..
This is forms at convergent
boundary, where subduction occurs
at a mid-ocean trench. The island
are a chain that form in an arc near
the trench.
12. Explain the role of silica in an explosive vs. non-explosive eruption.
Silica is material that makes
magma sticky and builds up
pressure in the volcano, causing
more explosive eruptions.
13. How could the gas, ash and debris from an explosive eruption affect the atmosphere and
biosphere?
Gas and ash could pollute the air and
lead to colder conditions because of
limiting the solar energy from
reaching Earth. Plants may be less
efficient at photosynthesis. Water
pollution could also occur from ash
and debris, harming aquatic life.
14. Explain how the Hawaiian Islands formed?
Hawaiian Island are hot spot islands,
forming when the tectonic plate moves
over the hot spot.
15. Explain how Mt. Saint Helens formed?
This is a composite volcano. This is
formed by subduction at a convergent
boundary.