SEISMIC WAVE

 TSUNAMI or can be called Seismic Wave. Caused by Earthquake.



What is Seismic Waves?

Seismic Waves are waves of energy that travel through the earth, and are a result of an earthquake–sudden vibration or shocks that occur in the Earth’s surface due to the release of energy, and is caused by the movement of the Earth’s cracks–, explosion, or a volcano that imparts low-frequency acoustic energy. Some of seismic waves are tsunami–water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions landslides, glacier calving, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami. Tsunami waves do not resemble normal sea waves because their wave length is far longer. The height of the wave in Deep Ocean is only around 1 meter, thus, the wave is not felt by the ships which were in the middle of the sea. But, when it’s approaching the swallow water (beach), the velocity of the tsunami wave decreases to around 30 km/hour, but its height increased to tens of meters.

Seismic wave have two types of waves and they all move in different types. They are; body wave that travel through the earth’s inner layers. Surface waves move along the surface of the planet like ripples on water. Body waves have two types; Primary waves and Secondary Waves.

The first kind of body wave is the P wave or primary wave. This is the fastest kind of seismic wave. The P wave can move through solid rock and fluids, like water or the liquid layers of the earth. Sometimes animals can hear the P waves of an earthquake. Dogs commonly begin barking hysterically just before an earthquake hits. The second kind of body wave is S wave or secondary wave, which is the second wave felt in an earthquake. An S wave is slower than a P wave and can only move through solid rock, not through any liquid. S waves move rock particles up and down, or side-to-side perpendicular to the direction that the wave is traveling in.

Surface waves have two types.The first type is Rayleigh wave, Rayleigh waves rolls along the ground just like a wave rolls across a lake or an ocean. Because it rolls, it moves the ground up and down and side-to-side in the same direction that the wave is moving. Most of the shaking felt from an earthquake is due to the Rayleigh wave, which can be much larger than the other waves. The second type is Love wave; the fastest surface wave and moves the ground from side-to-side. Love waves produce entirely horizontal motion.

Causes of Seismic Wave (Tsunami, Earthquake)

The cause of Earthquake is that the surface of the Earth is in continuous slow motion. The plates cover the entire surface of the globe. Since they are all moving, they rub against each other in some, sink beneath each other in some places or spread apart from each other. At such places the motion isn't smooth–the plates are stuck together at the edges but the rest of each plate is continuing to move, so the rocks along the edges are distorted. As the motion continues, the strain builds up to the point where the rock can’t withstand any more bending. With a lurch, the rock breaks and the two sides move. An earthquake is the shaking that radiates out from the breaking rock.

The causes of Tsunami are earthquakes, less commonly submarine landslides, infrequently by submarine volcanic eruptions and very rarely by a large meteorite impact in the ocean. Submarine volcanic eruptions have the potential to produce truly awesome tsunami waves. About two-thirds of the earth is covered by the waters of the four oceans. The Pacific Ocean is the largest, covering more than one third of the total surface area of our planet. The Pacific Ocean is surrounded by a series of mountain chains, deep ocean trenches and island arcs, sometimes called a "ring of fire." The great size of the Pacific Ocean and the large earthquakes associated with the "ring of fire" combine to produce deadly tsunamis.

The continents and sea floor that cover the earth's surface are part of a world-wide system of plates that are in motion. These motions are very slow only an inch or two per year.

Earthquakes occur where the edges of plates run into one another. Such edges are called fault lines or faults. Sometimes the forces along faults can build-up over long periods of time so that when the rocks finally break an earthquake occurs followed by tsunami. As the water get closer to the swallow water, the bigger wave it become.