By weakening and fracturing rock, weathering processes release nutrients and improve subsurface permeability. It is helpful to limit the physical attributes of materials produced by weathering inside the crucial zone in order to better understand these processes.
The permeability, strength, and seismic anisotropy of foliated rocks can be measured geophysically, whereas the first two have effects on hydrology and geomorphology. Characterizing weathering-dependent changes in rock fabric with depth may have a variety of implications because each of these types of anisotropy is connected to rock fabric.
The key points are:
In the critical zone, seismic surveys of weathered material reveal seismic anisotropy magnitudes that can reach 36% and that change with depth.
The strike of foliation and fracture planes found in bedrock coincides with the fast direction of wave propagation in weathered materials.
As bedrock is exhumed toward the surface, in-situ weathering processes probably intensify the anisotropy already existing in the rock.
