This is about seismic waves and why they travel at the speeds they do when travelling through different compositions
2007-12-13 07:07:26 · 6 answers · asked by daz171084 1 in Science & Mathematics ➔ Earth Sciences & Geology
What is meant is that the core and mantle have different compressibility. If one of them was completely incompressible, seismic waves would travel at infinite speed in that material. But that is physically impossible.
2007-12-13 07:13:20 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The outer core of the earth is liquid so is compressible the inner core is solid so incompressible. The mantle is compressible in the part called the Aesthenosphere, Which means weak, because it is close to melting. In fact it melts at construction boundaries of the tectonic plates by decompression to form oceanic basalt.The aesthenosphere also allows the earth's tectonic plates to slide over it because of the weakness.
2007-12-14 02:32:12 · answer #2 · answered by JOHN M 2 · 0⤊ 0⤋
Outer core is made out of sand , minerals and rocks all are compressible. But the mantle is a liquid core and can not be compressed.Wave speed will vary when the density of the medium differs and there will be refraction also. That is the direction change.
2007-12-13 12:35:11 · answer #3 · answered by A.Ganapathy India 7 · 0⤊ 0⤋
Perhaps talking at cross purposes here. Longitudinal seismic waves of compression and rarefaction travel in solids liquids and gases depending on density (obv fastest in solids). Transverse seismic waves only travel in solids so cannot penetrate the liquid part of the mantle or outer core.
Their speed is inversely propnl to the density of the material so they would be slower.
There are also surface waves-transverse waves which vibrate in the plane of the earth's surface and waves which vibrate perpendicular to the plane like s-waves, but only in the 'skin' of the surface.(a bit like surface water waves)
2007-12-13 08:26:28 · answer #4 · answered by azteccameron1 4 · 0⤊ 0⤋
I think the outer part of earth is compressible because of that the pressure is low. Then an increase of pressure result in a decrease of volume. The outer masses are elastic.
In the inner parts there is a stable pressure that is very high, and the volumes are in a stable situation to that.
Ther is a strange situation near center of planets.
Gravitation is near zero, but liqid pressure is from masses above is big. Little variation in there i hope.
2007-12-13 08:55:42 · answer #5 · answered by anordtug 6 · 0⤊ 0⤋
Yeh.....what he said!
2007-12-13 07:20:45 · answer #6 · answered by Anonymous · 0⤊ 0⤋