Gum disease generally develops because of improper brushing and flossing habits, although underlying medical conditions may have a correlation to greater incidence. The bacteria that are found in the mouth as a result of these poor habits begin to affect the surrounding bone and tissues below the gumline.
Most earthquakes occur at the boundaries where the plates meet. In fact, the locations of earthquakes and the kinds of ruptures they produce help scientists define the plate boundaries. There are three types of plate boundaries: spreading zones, transform faults, and subduction zones.
Tsunamis occur most frequently in the Pacific, particularly along the Pacific Ring of Fire . This zone is found at the northern edge of the Pacific Plate and refers to the geologically most active fields of the earth. Several times a year, strong earthquakes of at least 7 on the Richter scale result in tsunamis.Japan, for example, is hit by a tsunami at least once a year. From observations of scientists and historical sources, we know today that Tsunamis can occur in all larger seas of the world.everal times a year, strong earthquakes of at least 7 on the Richter scale result in tsunamis. Japan, for example, is hit by a tsunami at least once a year. From observations of scientists and historical sources, we know today that Tsunamis can occur in all larger seas of the world.