Transcript APES – Earth Systems

Earth’s Geology – 3 primary layers
Core, Mantle, and Crust
 Inner core is solid metal
(iron and nickle)
 Outer Core is molten
metal
 Rocky mantle (solid
silicate)
 Molten upper mantle
(athenosphere)
 Crust – thin silicate
rock (lithosphere)
Earth’s Crust has ~15 major plates
http://www.windows2universe.org/earth/interior/plate_te
ctonics.html
Convection currents cause plate
tectonics.
 Plates move 2-15 cm
per year – about the
rate your fingernails
grow!
Breaking News – July 2011
 Scripps Researchers Discover New Force Driving
Earth's Tectonic Plates
'Hot spots' of plume from deep Earth could propel
plate motions around globe
 Scripps Institution of Oceanography / University of
California, San Diego
 http://scrippsnews.ucsd.edu/Releases/?releaseID=1178

At least twice the
landmasses have joined
to form a
“supercontinent”.
Pangea existed about
220 mya
Pangea to today - Animation
 Choose the AVI and step it along.
http://www.ucmp.berkeley.edu/geology/tectonics.html
Three types of plate boundaries:
divergent, transform, and convergent.
Divergent plate boundaries
Two plates move
apart as magma
(liquid rock) rises
upward to create
new lithosphere.
Divergent plates - Mid-Atlantic
Ridge.
Spreading oceanic plates result in formation of new
crust on the ocean’s bottom (“seafloor spreading”) and
subduction of heavier oceanic plates beneath less
dense continental plates.
Mid atlantic ridge – a giant undersea mountain
range, started forming 20 million years ago as
Africa and S. America separated.
Transform plate boundary
Generate
earthquakes – eg.
San Andreas Fault
Do the Math
 If two cities lie on different tectonic plates, and those
plates are moving so that the cities are approaching
each other, how many years will it take for the two
cities to be situated adjacent to each other?
 Los Angeles is 630 km (380 miles) southeast of San
Francisco. The plate under Los Angeles is moving
northward at about 36 mm per year relative to the
plate under San Francisco. Given this average rate of
plate movement, how long will it take for Los Angeles
to be located next to San Francisco?
Convergent plate boundaries
If oceanic and continental
plates converge – one plate is
subducted and leads to
volcanism. – eg. Japan,
Mariana Trench, Cascades
Mtns, Andes Mtns.
Continental-continental convergence –
Himilayas and Appalacian Mountains
GEOLOGIC HAZARDS
Volcanoes
Earthquakes
 when molten rock, hot gas, or  shaking and release of energy
ash erupt through Earth’s
surface.
 Form at divergent plate
boundaries and subduction
zones, and over hot spots.
 Video – Ring of Fire IMAX
along tectonic plate
boundaries.
 Animation showing
cumulative earthquakes
 Video
http://www.pbs.org/wgbh/no
va/earth/earthquakedetection.html
Volcanoes – Hotspots
 Some “chains of volcanoes” form when mantle passes
over a relatively small, long-lasting, and exceptionally
hot regions -- called hotspots – that provide localized
sources of high heat energy (thermal plumes)
Hawaiian (and Galapagos) islands
form from “hotspot”
Figure 8.7 Plate movement over a hot spot. The Hawaiian Islands were formed
by volcanic eruptions as the Pacific Plate traveled over a geologic hot spot. The chain
of inactive volcanoes to the northwest of Hawaii shows that those locations used to
be over the hot spot. Numbers indicate how long ago each area was located over the
hot spot (in millions of years).
Yellowstone Volcano progression is
evidence for hotspot under mantle.
 Plot the data for recent volcanic eruptions on the map
on the worksheet – Tectonic Plates Part 1.
Ring of Fire – lots of volcanoes at
plate boundaries
Tsunamis can follow earthquakes
and volcanos.
 Dec 26, 2004 Tsunami, triggered by earthquake off
Sumatra, killed 228,000 people
Tsunami strikes Northern Japan on
March 11th, 2011
 Tsunami followed an
Earthquake of magnitude 8.4
GEOLOGIC HAZARDS
Volcanoes
Earthquakes
 when molten rock, hot gas, or  shaking and release of energy
ash erupt through Earth’s
surface.
 Form at divergent plate
boundaries and subduction
zones, and over hot spots.
 Video – Ring of Fire IMAX
along tectonic plate
boundaries.
 Animation showing
cumulative earthquakes
 Video
http://www.pbs.org/wgbh/no
va/earth/earthquakedetection.html
Liquefaction of
recent sediments
causes buildings
of sink
Two adjoining plates
move laterally along
the fault line
Earth movements
Cause flooding in
Low-lying areas
Landslides may
occur on
hilly ground
Shock
waves
Epicenter
Focus
Earthquakes
Richter Scale