ESS102H1 Study Guide - Midterm Guide: Pore Water Pressure, Plate Tectonics, Effective Stress
Document Summary
Stress on a surface is a vector (1st-order tensor), while state of stress at a point is a 2nd-order tensor, described by the equation: . Stresses in the lithosphere are almost everywhere compressional, even in rifts and other areas undergoing extension. Compressive stresses normally considered positive in geology, while tension is negative. In general, stress vectors act obliquely on planes and can be resolved into the normal and shear components. The stress ellipsoid and its orientation tell us everything about the state of stress at a given point in a rock, or in a rock volume in which stress is homogeneous. At the principal stress axes, the shear stress is zero because they are the poles to the principal planes of stress. Can define a stress tensor or stress matrix where the normal stresses 11, 22, and 33 occupy the diagonal and the off-diagonal terms represent the shear stresses.
