Transcript Science Q and A

Science Q and A
Molly Boyd
And
Megan Brooker
How many “supercontinents” did the
Continental Drift theory assume?
• In 1912 Alfred
Wegner’s theory of
Continental Drift
consisted of one
“supercontinent”
called Pangea that
broke apart about 250
million years ago.
What are the major plates that
affect the U.S.?
• The tectonic plates
that affect the U.S.
are the North
American Plate, Juan
de Fuca Plate, Pacific
Plate and counting
Puerto Rico the
Carribean Plate.
Why does California have so many
earthquakes but Florida doesn’t?
• Florida is sitting on the
middle of the North
American Plate so it is
seismically inactive.
California lies on the
junction of the Pacific
Plate and North American
Plate (San Andreas Fault)
and when they slip past
each other earthquakes
happen.
What is considered the most
destructive earthquake in history?
• An earthquake in
Shensi, China on Jan.
23, 1556 had a
magnitude of eight
and abt. 830,000
deaths and damage
extended as far as
270 mi. from the
epicenter.
What are the three basic plate
boundaries?
• Divergent: plates go
apart in opposite
directions.
• Convergent: plates
push together.
• Transform: plates slip
past each other (ex.
San Andreas Fault)
What are tsunami’s?
• An earthquake
happens underground
which causes a huge
wave to come up over
the land. On average
about 500 mi. which
is as fast as a
commercial jet.
What are two types of energy
waves from an earthquake?
• Primary waves: travel
first and go through
all three types of
matter.
• Secondary waves:
come second and
only travel through
solids, 60% slower
than primary waves.
How much more energy is released
in a 7.2 than a 6.2 earthquake.
• It releases about 10x
more ground motion
but 32x more energy.
What applications does seismology have besides
measuring magnitude and location of earthquakes?
• It can provide
information on
internal structure and
state of matter. Also
useful in reflection
and refraction
seismology and
geophysical
exploration to locate
layers of different
density.
Where did the most earthquakes
happen last week?
• The most
earthquakes
happened in Alaska
last week.
Can scientists predict
earthquakes?
• No, and it’s doubtful
they ever will
because they can
only observe from a
distance. They also
don’t know if there’s
a process an
earthquake goes
through and if it
differs with the size
of earthquake.
How do scientists know where an
earthquake actually occurred?
• They use data from at least
three seismograph stations
and perform a calculation
called triangulations. This
involves using the travel
times of primary and
secondary waves recorded at
each station to find the
earthquake’s distance. Once
you have enough data you
plot circles at the radius and
where the circles meet is the
epicenter.
CREDITS
Pictures: Molly Boyd
Sound effects: Molly Boyd
Information: Megan Brooker
Emotional support: Megan Brooker
Powerpoint: Megan Brooker and Molly Boyd