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.
Large shallow earthquakes also happen where two plates are pulling apart with the creation of new oceanic crust along mid-ocean ridges and on the transform faults that intersect them. Shallow intraplate earthquakes occur in the relatively stable interior of continents away from plate boundaries.
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.