Earthstructure

Earthstructure is the study of the arrangement and properties of the Earth's interior and its surface expression, as used in geology and geophysics. It describes how the planet is organized physically and how that organization influences geophysical behavior.

Internally, Earth is described as crust, mantle, and core. The crust comprises continental crust, thicker and granitic, and oceanic crust, thinner and basaltic. Beneath it lies the mantle, extending to about 2,900 kilometers, divided into upper and lower mantle. The boundary between mantle and core is the Gutenberg discontinuity; between crust and mantle lies the Moho discontinuity. The core consists of a liquid outer core and a solid inner core, with the outer core about 2,200 to 2,300 kilometers thick.

Lithosphere includes the crust and rigid upper mantle and sits on the more ductile asthenosphere. Plate tectonics arise from their movement, creating mountains, earthquakes, volcanism, and shaping ocean basins and margins.

Composition varies by layer: crust is lighter and silica-rich; mantle is ultrabasic peridotite; outer core is iron-nickel liquid that generates the geomagnetic field; inner core is solid due to pressure.

Study methods include seismology, gravity, magnetometry, and electrical sounding. Seismic tomography and other imaging reveal density and phase changes with depth.

Understanding Earthstructure informs geologic history, resource distribution, natural hazards, and planetary dynamics.