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.
The swelling results from inflammation or a buildup of fluids in the tissues surrounding your eyes. The causes for this range from mild infections, and inflammation to more serious causes such as infections and malignancy. There also are some more specific causes for swollen eyelids. Eyelid cysts are one of them.