Scientists think that the lithosphere broke into pieces, called tectonic plates, some 3.8 billion years ago. Most earthquakes are caused by the large-scale movement of these lithospheric plates and occur at boundaries between the plates.

Experts recognize seven to twelve major plates and a number of smaller ones. The plates take their names from continents (the North American Plate) from oceans (the Pacific Plate) and from geographic areas (the Caribbean Plate).

The plates are in very slow but constant motion so that, seen from above the Earth’s surface, it might look like a slow-moving spherical jigsaw puzzle. The plates move at a rate of 2-15 cm, or several inches, in a year.

Three Types of Plate Movements

The movement of the plates is generally one of three kinds: spreading, colliding or sliding.

  1. Spreading: when plates are spreading or separating from each other, we call the movement divergent.
  2. Colliding: when plates are colliding, or pushing each other, we call the movement convergent.
  3. Sliding: when plates are sliding past each other we call this movement lateral plate movement.

Earthquakes can accompany each of the three types of movement.

Source: ODPEM

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