Seismology and Earth's Interior

Understanding the Earth's interior is derived from seismic wave analysis, volcanic material studies, and theories of Earth's origin.
Primary waves (P-waves) reach the Earth's surface, while secondary waves (S-waves) do not penetrate liquids, indicating the presence of liquid layers.
Scientific instruments that record seismic waves provide insights into the density, pressure, and temperature of the Earth's interior.
Volcanic eruptions bring molten material from deep magma chambers to the surface, aiding in the understanding of Earth's composition.
Meteorite analysis supports theories that the Earth consists of materials found in meteorites, lending insight into its elemental makeup.
The Earth's internal heat is generated by radioactive elements, with thermal studies helping estimate internal temperatures.

The Earth comprises several concentric layers: the crust (lithosphere), hydrosphere (underwater parts), and atmosphere (gaseous blanket around Earth).
The lithosphere, the outermost crust, is the thinnest layer, enriched with silicates, feldspar, and mica.
Lithosphere divisions: SIAL (Silica and Aluminium) forms continents and is less dense, while SIMA (Silica and Magnesium) makes up the ocean floor.

The core, the densest region, is approximately 7000 km in diameter, formed mostly of iron (Fe) and nickel (Ni).
Temperature within the core ranges from 4400°C to 6000°C, contributing to Earth's magnetism, with the magnetic field oriented towards the poles.
The inner core remains solid due to extreme pressure, while S-waves do not travel through the outer core, indicating a molten state.

Located beneath the crust, the mantle averages 2900 km in thickness and comprises 84% of Earth's total volume.
Divided into the upper and lower mantle:
- The upper mantle (700 km deep) consists of cooler, solid rocks.
- The lower mantle, from 700 km to 2900 km, is hotter and denser.
At depths of 100-410 km, the mantle turns partially molten, forming the asthenosphere.
With increasing pressure, density rises, and temperatures vary from 1000°C to 3700°C.
The Gutenberg Discontinuity marks the boundary between the mantle and core, beginning at a depth of 2800 km, where seismic wave behavior changes significantly.