2. `
Seismic
Waves
These are the waves of
energy caused by the sudden
breaking of rock within the
earth or an explosion. They are
the energy that travels
through the earth and
recorded on seismographs.
3. `
Types Seismic
Waves
Body waves - arrive before the surface waves
emitted by an earthquake. These waves are of a
higher frequency than surface waves.
Surface waves(L-Waves) - are of a lower
frequency than body waves, and are easily
distinguished on a seismogram as a result. Though
they arrive after body waves, it is surface waves
that are almost entirely responsible for the damage
and destruction associated with earthquakes. This
damage and the strength of the surface waves are
reduced in deeper earthquakes.
5. `
Primary Waves
Primary wavesare “compression waves”.
They push and pull the rocks of the earth's surface. They can move
through solid rock and fluids like water or the liquid core layers of the earth And
first to 'arrive' at a seismic station.
6. `
Primary waves push and pull on the rocks through which
they are traveling. This creates a back and forth movement
on the Earth's surface. This is just like sound waves pushing
and pulling the air. Have you ever heard a big clap of thunder
and heard the windows rattle at the same time? The windows rattle because the
sound waves were pushing and pulling on the window glass much like P-waves
push and pull on rock.
Primary Waves
7. `
Secondary Waves
Secondary waves travel slower than primary waves. Also called “shear waves
"or “Transverse Waves”.
They create a side to side motion in the rocks through which they are
traveling.
8. `
Secondary Waves
Unlike the other earthquake waves, S-waves cannot
travel through water or the liquid rock of the Earth's
core layer. They can Travel through solid only-waves will rock buildings side-
to-side.
9. `
Remember...
Primary Waves
Secondary Waves
Also Called as Compression Waves.
They Push and Pull the rock in the earth’s surface
Also Called as Shear/Transverse Waves.
They Push and Pull the rock in the earth’s surface
11. `
Surface Waves(L-Waves)
Land waves move along the surface of the earth and cause it to move
up and down like something bobbing on the surface of the ocean.
12. `
Surface Waves(L-Waves)
Land waves only move along the surface of the earth.
Their speeds vary depending on the material, rock or soil,
forming the surface. These waves cause the surface to
move up and down. These are the waves that cause
The to buildings and other structures
during an earthquake.
13. `
Named after A.E.H. Love, a British mathematician
who worked out the mathematical model for this
kind of wave in 1911.
Love Waves
Love waves travel with a lower velocity than P or
S waves, but faster than Rayleigh waves. These
waves travels in lithosphere only.
14. `
These waves are a type of surface acoustic
wave that travel on solids
Rayleigh Waves
Named for John William Strutt, Lord
Rayleigh, who mathematically predicted
the existence of this kind of wave in 1885.
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.
16. `
Remember...
Love Waves
travels through lithosphere only. Has
Low Velocity but faster than Rayleigh
waves.
Rayleigh Waves
travel on solids and Rolls along the ground
17. `
Questions:
1. Other term for primary waves and secondary waves
2. Differentiate the P and s waves
3.Love waves are named after a mathematician. What is the name of the
mathematician ?
4.How about rayleigh waves. What is the name of the mathematician ?
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