EARTHQUAKES & TSUNAMIS

by: Ronald Garcia


Earthquakes

external image kobe_earthquake.jpg
Princeton dictionary defines earthquakes as "shaking and vibration at the surface of the earth resulting from underground movement along a fault plane of from volcanic activity ".
Many earthquakes are formed because a series of foreshocks that lead to a large shock called an earthquake.
Aftershock: Following an earthquake aftershocks may hit within at least the following two days.
Intensity of these quakes may diminish as time passes. The reason why aftershocks occur is because after plates have collided for the initial shock, their sides still need to adjust to their new surfaces, and therefore they rub against each other and create a series of smaller sized shocks

P-Waves

Waves that act like soundwaves, they compress and expand. external image pwave.jpg

S-Waves

Shears the rock sideways at right angles to the direction of travel, therefore it cannot propagate in the liquid parts of the earth, such as oceans and lakes.
external image swave.jpg


Love-Wave

The ground moves from side to side in a horizontal plane.
external image lovewave.jpg

Rayleigh-Wave

Depending on where the wave is traveling Rayleigh waves will move both vertically and horizontally in a vertical plane towards that direction.
external image raywave.jpg

Earthquakes are the main cause of the following topic, tsunamis.


Tsunamis

According to the University of Washington a tsunami is "a wave train, or series of waves, generated in a body of water by an impulsive disturbance that vertically displaces the water column".
Many things can cause a tsunami to be created, some are Earthquakes, landslides, volcanic eruptions, explosions, and even the impact of cosmic bodies, such as meteorites, can generate tsunamis.
external image tsunami-formation.gif



Sources:
First Picture: http://heavenawaits.files.wordpress.com/2008/05/kobe_earthquake.jpg
P-wave Picture: http://allshookup.org/quakes/pwave.jpg
S-Wave Picture: http://allshookup.org/quakes/swave.jpg
Love-Wave Picture: http://allshookup.org/quakes/lovewave.jpg
Rayleigh-Waves Picture: http://allshookup.org/quakes/raywave.jpg
Tsunami Picture: http://static.howstuffworks.com/gif/tsunami-formation.gif
Information for Earthquakes: IRIS (Incorporated Research Institutions for Seismology)
Wave type Information: http://allshookup.org/quakes/wavetype.htm
Information for Tsunamis: University of Washington.