Which wave mode is typically more sensitive in detecting surface flaws?

Surface waves are typically the most sensitive to detecting surface flaws. This is because surface waves propagate along the interface of materials, meaning they are more affected by any discontinuities or flaws present close to the material's surface. While longitudinal and shear waves can also detect flaws, they penetrate the material more deeply and are not as sensitive to irregularities located right at the surface.

Shear waves, in particular, are effective in detecting internal defects and can sometimes provide insights into flaws located beneath the surface. However, their ability to detect surface defects is limited compared to surface waves, which are specifically designed to maximize sensitivity to such flaws.

In summary, the correct answer emphasizes the unique characteristics of surface waves that make them ideal for identifying surface defects, allowing inspectors to effectively assess and ensure the integrity of materials being tested.