What are Focus Waves??

Question

I believe they have something to do with volcanoes/earthquakes/the earth's crust.

Can someone help me out?

Answer 1

Focus waves are P(Primary) and S (Secondary or Shear) waves that originate at the focus of an earthquake.  The focus is the point underground where the earthquake actual occurs.  The point on the ground directly above the focus is called the epicenter.

Also called compressional or longitudinal waves, P waves are the fastest seismic waves produced by an earthquake. They oscillate the ground back and forth along the direction of wave travel, in much the same way as sound waves, which are also compressional, move the air back and forth as the waves travel from the sound source to a sound receiver.

S waves oscillate the ground perpendicular to the direction of wave travel. They travel about 1.7 times slower than P waves. Because liquids will not sustain shear stresses, S waves will not travel through liquids like water, molten rock, or the Earth's outer core.

More info at:

http://everything2.com/e2node/body%2520w...

Answer 2

The other name for focus wave is body wave. There are mainly 4 types of waves generated from earthquakes.The focus is the point inside the earth where the earthquakes generated.

1.P wave is the primary wave. Generated from the point called focus. The speed of this wave is from 13 to 17 kilo meters per second. Moves the particles in its direction of propagation. you can assume that this is non destructive wave. 2.The secondary waves comes from the point of focus. The speed is nearly half of the primary wave. This moves the particles perpendicular to the direction of its propagation. Destructive. Do not pass through liquid. These waves are called body waves. generated from earthquakes. The3.rd L wave and 4th R waves are most dangerous waves coming from the surface of the earth. These waves are coming because of reflection and refraction. These are called surface waves. The speed is slower than other two waves. There are real confusion in my mind about the seismograph recorded about 2 years back in Singapore. There was a gap of about 3 minutes between p wave and maximum shaking recorded. Now only I was able to understand why the time gap was such a long even though the epicenter was only 500 k/m from Singapore. Because the primary wave reached through sea water where as other waves got reflected and refracted under the sea several times and arrived late. The earthquake alarm designed by me has helped me to issue the warning 2 hours before it struck our coast.

Answer 3

focus waves are when waves comes from the focus of volcanoes or earthquakes.