EARTHQUAKES!!!

Earthquakes 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 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 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 3/17 la eq center/ia_graph_travel_time_animation.html Mystery Earthquake animations: center/show.html

TO know the EPICENTER:(where quake started) EPICENTER 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.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)(triangulation)

VOLCANOES A hole in Earth’s crust through which lava flows from underground.

Origin 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 boundaries Most volcanoes occur along plate boundaries

Hot 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