izostatik

Izostatik, the Turkish term for isostasy, is the geological principle describing gravitational equilibrium between the Earth's lithosphere and the underlying mantle. The lithosphere behaves as a floating shell that adjusts its thickness and elevation so that its weight is balanced by buoyant forces in the mantle. This balance helps explain why continental crust sits higher than oceanic crust and how large ice sheets can depress the crust to form substantial roots.

Two classical models capture how isostatic balance can be achieved. The Airy model posits that topography is supported by variations in crustal thickness: thicker roots provide more buoyancy. The Pratt model assumes uniform crustal thickness but lateral density differences within the crust compensate the load. In practice, real lithosphere combines density contrasts and thickness changes, and modern theories include flexural isostasy, which accounts for lithospheric bending and dynamic mantle flow.

Isostasy is a dynamic process. When surface loads change, such as after deglaciation or erosion, the crust and mantle respond in a process called isostatic rebound or glacial isostatic adjustment, often detectable with GPS, gravity surveys, and seismic studies. Evidence includes postglacial rebound in formerly glaciated regions and regional gravity anomalies that track crustal structure.

Applications include interpreting long-wavelength topography, estimating crustal thickness, and understanding regional geodynamics. Isostasy remains a foundational concept in geology, geodesy, and geophysics, linking surface relief to deep Earth structure.