The first two wave types, P and S , are called body waves because they travel or propagate through the body of Earth. The latter two are called surface waves they the travel along Earth's surface and their amplitude decreases with depth into Earth.
The causes are many and can have bacterial infection, seborrheic dermatitis of the face or even a scalp, rosacea, allergies, and in very rare cases, the lice. If the itchy eyelids is brought about by seborrheic dermatitis then you may develop dry, flakey patches of skin on the eyelid.
A swollen or puffy eyelid is common. Causes can range from fluid retention to a severe infection. In most cases, the swelling goes away within 24 hours. You can reduce the swelling with compresses, but how you treat a swollen eyelid also depends on the cause. Several reasons your eyelid may be swollen include: allergies; bug bite; fluid retention