Earthquake tremors and vibrations of the surface of the Earth caused by natural causes (mainly tectonic processes), or (sometimes) artificial processes (explosions, filling reservoirs, the collapse of the underground cavities of a mine). Small tremors may also be caused by the rise of lava during volcanic eruptions. Each year on the whole Earth is about a million earthquakes, but most of them are so insignificant that they go unnoticed. Really strong earthquakes can cause extensive damage to happen on the planet about once every two weeks. The majority of the bottom of the ocean, and therefore is not accompanied with catastrophic consequences (if the earthquake under the ocean without tsunami).
Each year on the whole Earth is about a million earthquakes, but most of them are so insignificant that they go unnoticed. Really strong earthquakes can cause extensive damage to happen on the planet about once every two weeks. The majority of the bottom of the ocean, and therefore is not accompanied with catastrophic consequences (if the earthquake under the ocean without tsunami).