Scientists observe where these waves reach the surface and how long it takes for them to get there.
Comparing these observations with controlled experiments on the behavior of waves passing through different materials, scientists can then construct good theories about what materials deep in the Earth the seismic waves passed through on their way to the surface.
(And a level 5.0 quake is 100 times stronger than a level 3.0).The number given to the strongest earthquake described by the Richter scale is 8.9 (An 8.9 quake is more than 79 million times stronger than a 1.0 quake!The solid, central part of the core has a liquid (molten) layer surrounding it.Outside the core, the largest mass of planet Earth is called the mantle and this is mostly solid rock.Some deductions are based on good empirical (based on observation or experiment) data obtained by analyzing the seismic waves that are produced when earthquakes happen.
Seismic waves that travel through the deep interior of the Earth can sometimes be detected by seismographs in different parts of the world.Scientists theorize (no-one really knows because no one was there!) that these gases were methane, ammonia, carbon dioxide and water (steam).) When Earth was first formed it was a solid ball of molten rock with no atmosphere.As Earth began to cool and the crust and mantle began to harden, material from the inner regions would sometimes erupt through the surface bringing hot gases.Each time a planetisimal (see the Introduction) hit the rotating chunk of material that was to become Earth it melted in to the existing mass.