Structure of the Earth

The Structure of the Earth refers to the layered composition and physical characteristics of the planet Earth. Understanding the Earth's structure is crucial for various fields such as geology, seismology, and plate tectonics. The Earth can be divided into several distinct layers: the crust, the mantle, the outer core, and the inner core.

Crust

The Earth's crust is the outermost layer and is composed of solid rock. It is subdivided into two types: the continental crust, which forms the continents and has a granitic composition, and the oceanic crust, which forms the ocean floors and has a basaltic composition. The thickness of the crust varies from about 5 kilometers under the oceans to up to 70 kilometers under large mountain ranges.

Mantle

Beneath the crust lies the mantle, which extends to a depth of about 2,900 kilometers below the surface. The mantle is composed of silicate rocks that are richer in iron and magnesium than the crust. It is divided into the upper mantle and the lower mantle; the upper part includes the asthenosphere, a region of partially molten rock that allows for the movement of tectonic plates.

Core

The core of the Earth is divided into two parts: the outer core and the inner core. The outer core is a liquid layer about 2,200 kilometers thick, composed mainly of iron and nickel. This liquid layer is responsible for Earth's magnetic field through the process of dynamo action. The inner core is solid and extends to the center of the Earth, at about 6,371 kilometers from the surface. It is also composed primarily of iron and nickel and has a higher density than the outer core.

Geophysical Properties

The structure of the Earth is characterized by a gradual increase in density and temperature with depth. The temperature at the boundary between the crust and the mantle, known as the Mohorovičić discontinuity or "Moho," is around 200 to 400 degrees Celsius. Temperatures in the core can reach over 5,000 degrees Celsius, which is comparable to the surface temperature of the Sun.

Exploration and Study

The structure of the Earth is studied using various techniques, including seismic waves generated by earthquakes. Seismologists analyze the speed and path of these waves to infer the properties of materials they pass through, providing crucial information about the Earth's internal structure.

See Also

• Plate tectonics
• Earth's magnetic field
• Seismology