1 Inflammation of the gingiva, bone loss, and increased gingival recession may progress slower than with other forms of periodontitis.  Periodontitis Associated with Systemic Diseases - Systemic diseases, such as heart disease, diabetes, and certain forms of arthritis, may have a correlation with periodontitis.
Main Content. An earthquake is ground shaking caused by a sudden movement of rock in the earthâs crust. Such movements occur along faults, which are thin zones of crushed rock separating blocks of crust.
Quick Answer. Most earthquakes occur along the boundaries between the Earth's tectonic plates. The crust of the Earth is divided into plates. When a plate collides with or slides past another plate, this causes earthquakes. For example, as the Pacific plate moves past the North American plate, many earthquakes occur along the coast of California.