Earthquakes Science

PLATE TECTONICS

Continental drift: the theory proposed in 1915 by Alfred Wegner. The idea was that continents were joined into a “super continent” called Pangea.

Lithosphere: the rigid upperlayer of the Earth consisting of the crust and the upper mantle.

Asthenosphere: the semi- molten layer of the Earth which starts at 70-200 km depth and ends at 660 km.

Earth’s inner composition:crust: the uppermost 5-70 km of the Earth. These are two types of crust: continental and oceanic.

Mantle: the middle portion of the interior of the Earth, starting below the crust at 5- 70 kmbelow the Earth’s surface and continuing to a depth of 2900 km

Core: the inner most layer of the Earth, which starts at 2900 km depth. The core is composed mainly of iron and consists of a moltenouter core and a solid inner core.


Boundaries:
-divergent (spread apart)- sea floor spreading, ocean ridges, valleys and rifts, trenches
-convergent (come together)- mountains, volcanoes,-transform fault (where 2 plates slide horizontally pass one through another.)- earthquakes
EARTHQUAKES


Seismic waves: the vibrations of the ground produced during an earthquake.

P- waves: alsoreferred as primary waves, squeeze and push rocks in the direction along which the waves are traveling.

S- waves: also called secondary waves, they are slower than the p-waves, so they are thesecond set of waves to be felt. S-waves have a motion that causes rocks to move perpendicular to the direction of the waves.


Surface wave: the third and slowest type of waves, they travel only alongEarth’s surface. They cause the ground to move sideways and up and down like ocean waves.











Epicenter: the part of Earth’s surface directly above the focus of an earthquake.Focus: the point of failure where the waves originate.



Richter Scale: the amount of energy released and the amplitude of seismic waves are measured.

Mercalli Scale: seismic scale used for...