Which term is used to describe the influence of the Poisson effect on horizontal stress in crustal rocks?

Which term is used to describe the influence of the Poisson effect on horizontal stress in crustal rocks?

• A. Gravity
• B. Overburden
• C. Poisson's Ratio Effect
• D. Thermal Expansion

Answer: (C)

Poisson's ratio describes how a material deforms laterally when it is stressed in another direction. In crustal rocks, the vertical load from overlying rocks (the overburden) compresses the rock, and because rocks have a finite Poisson ratio, this vertical compression is accompanied by a horizontal change in dimensions. That coupling is what alters the horizontal stress state, so the influence of the Poisson effect on horizontal stress is described as the Poisson’s Ratio Effect. This concept helps explain why horizontal stresses are linked to vertical loading and how the rock’s elastic properties govern their interaction. Gravity and overburden refer to the vertical stresses from weight, not the lateral coupling, while thermal expansion involves temperature-driven changes, not the lateral-vertical stress relationship described by Poisson's ratio.

Poisson's ratio describes how a material deforms laterally when it is stressed in another direction. In crustal rocks, the vertical load from overlying rocks (the overburden) compresses the rock, and because rocks have a finite Poisson ratio, this vertical compression is accompanied by a horizontal change in dimensions. That coupling is what alters the horizontal stress state, so the influence of the Poisson effect on horizontal stress is described as the Poisson’s Ratio Effect. This concept helps explain why horizontal stresses are linked to vertical loading and how the rock’s elastic properties govern their interaction. Gravity and overburden refer to the vertical stresses from weight, not the lateral coupling, while thermal expansion involves temperature-driven changes, not the lateral-vertical stress relationship described by Poisson's ratio.