earthquakes!!!. earthquakes earthquake: sudden movement of rock sliding along a fault in the...
TRANSCRIPT
EARTHQUAKES!!!
EarthquakesEarthquakes
• Earthquake: Sudden movement of rock sliding along a fault in the earth’s crust
• Releases energy as this occurs.
• Energy release produces strong vibrations called seismic waves.
Energy ReleaseEnergy Release• Edges of the plates get stuck while
the rest of the plate keeps moving.—Energy stored up
• When the force of the moving blocks finally overcomes the friction of the jagged edges of the fault and it unsticks, all that stored up energy is released.
• The energy radiates outward from the fault in all directions in the form of seismic waves like ripples on a pond. –This is the earthquake
Earthquake WavesEarthquake Waves
• Focus- point of earthquake origin
• Epicenter- point on earth’s surface above the focus
• Primary Waves ( P-wave)– Travel through solids and
liquids– Travel FAST!
• Secondary Waves (S-waves)
– Only travel through solids– Travel SLOWER than P-waves
Longitudinal Waves (L-waves)-- Travel on earth’s surface
http://losangeles.cbslocal.com 3/17 la eq
http://earthguide.ucsd.edu/mystery_detectives/teach/epicenter/ia_graph_travel_time_animation.html
Mystery Earthquake animations: http://earthguide.ucsd.edu/mystery_detectives/teach/epicenter/show.html
TO know the TO know the EPICENTER:(where quake started)
• Seismic waves radiate out from the source in all directions.
• Siesmograph stations recieve p and s waves and use the difference in arrival time to determine the distance away.
• Different stations compare the information recorded at the same time.
Seismic Station picks up p and s waves and determines they came from
an earthquake 10 km away.
But 10 km from which direction?
A second seismic station records the same quake at 5 km away.This narrows down the epicenter to 2 spots.
To pinpoint the epicenter, 3 seismic stations must record
the quake. (triangulation)
VOLCANOESVOLCANOES
• A hole in Earth’s crust through which lava flows from underground.
Origin of MagmaOrigin of Magma
• Molten rises from the Earth’s asthenosphere (upper mantle) to the Earth’s surface through cracks creating a volcano.
Most volcanoes occur along plate Most volcanoes occur along plate boundariesboundaries
Hot SpotsHot Spots
• Volcanically active sites that arise in places where large quantities of magma move to the surface in large, column-like plumes– Can occur away from plate boundary
– When under a oceanic plate, volcanic island chains forms
• Mountains—folding and faulting; convergent continental boundaries
• Plateau– eroded mountain