Earth Structure and Tectonic Plate Dynamics

Earth's Internal Structure

The planet is composed of several distinct layers:

• Core: Composed of iron and nickel. It features a solid inner part and a liquid outer layer with a density between 3 and 10 g/cm³. Internal temperatures reach approximately 6800K, decreasing toward the exterior.
• Mantle: A massive body of rigid rock subjected to extreme pressure, with temperatures ranging from 2000K to 3500K.
• Crust: Composed of solid rock. It is divided into continental plates (up to 100km deep) and oceanic plates (10km deep), which move relative to each other, permanently altering the distribution of continents.
• Asthenosphere: A highly deformable, plastic layer upon which the lithosphere floats.

Elemental Composition of Earth

The Earth is primarily composed of the following elements:

• Iron: 35%
• Oxygen: 28%
• Magnesium: 17%
• Silicon: 13%
• Nickel: 2.7%
• Sulfur: 2.7%
• Calcium: 0.6%
• Aluminum: 0.6%
• Other: 0.4%

Planetary Shape and Temperature

The Earth is flattened at the poles due to rotational forces. Recorded surface temperatures are as follows:

• Minimum: -86.6°C
• Average: 15°C
• Maximum: 58°C

Detailed Geological Layers

• Inner Core: Metals remain in a solid state due to extreme external pressure.
• Outer Core: Liquid state with a thickness of 2250km.
• Mantle: Composed of silicates, magnesium, iron, and sodium.
• Crust: Composed of silicates with a thickness of 40km; its density is three times that of water, representing 1% of the Earth's mass.

Tectonic Plates

Tectonic plates are the segments of the Earth's crust that are not fixed but move across the surface. These plates are driven by convection currents within the mantle.

Types of Tectonic Plates

• Oceanic Plates: Covered entirely by thin oceanic crust of basic composition. Notable examples include the Pacific, Nazca, Cocos, and Philippine plates.
• Continental Plates: Thick plates that contain continents, such as the South American plate and the Eurasian plate.