asthenosferic

Asthenosferic is an adjective used in geology to describe features, processes, or materials associated with the asthenosphere, the weak, ductile portion of the Earth’s upper mantle beneath the lithosphere. The asthenosphere lies beneath most of the planet’s surface, from roughly 100 kilometers depth to several hundred kilometers, with the base varying by region and tectonic setting.

Physically, the asthenosphere is hotter than the overlying lithosphere and composed of mantle rocks that deform by flow rather than brittle fracture. This ductile behavior is enhanced by partial melting and elevated temperatures, leading to slow, viscous flow that can accommodate the movement of tectonic plates. The region is commonly identified by a low seismic shear-wave velocity, high anelasticity, and a reduced rigidity compared with the overlying lithosphere.

Seismological studies reveal a low-velocity zone within the upper mantle that is interpreted as the asthenosphere. Its properties reflect higher temperatures, possible partial melt, and mineralogical changes that soften rocks. The existence and character of the asthenosphere help explain why the rigid lithospheric plates can move atop a weaker, more deformable layer.

Geodynamically, ashrenosferic conditions enable decoupling of the plates from the deeper mantle, facilitating plate tectonics and mantle convection. Variations in thickness, temperature, and composition across different tectonic settings influence local deformation, anisotropy, and heat transport, making the asthenosferic region a central factor in understanding Earth’s dynamic geology.