Earthquakes commonly occur in the ocean and can range from small trembles to as high as 9.2 on the Richter scale. Strike-slip, dip-slip and subduction are the three types of earthquakes. Strike-slip eartquakes occur when the ocean floor moves back and forth. Dip-slip earthquakes happen when the ocean floor moves up and down. Subduction earthquakes form when plates of the earth's crust stack on top of one another. When earthquakes happen underwater, it can result in a tsunami wave.
Causes of Underwater Disturbance
On the ocean floor, the Earth's crust is a series of rock islands that are floating. These rock islands, or plates, are constantly shifting throughout time. These plates can eventually rub against, bump into or drift away from each other. This action can result in volcanic action, mountains forming or earthquakes occurring. An ocean floor earthquake happens when two plates push against each other and form a new underwater island. This formation of new land results from the ocean floor rising.
What Happens When New Islands Form
Subduction earth movements is the cause of new underwater islands and results in a displacement of ocean water. It happens when an ocean plate slides beneath a continental plate. This sliding action progresses to form wedges that are constructed from ocean sediments from the floor. These wedges happen above and beneath the edge of the continental plate. Due to high friction between the plates, they become stuck together. The overlying plate edge is dragged further underneath the mass and buckles. With great force, the overlying plate bounces back and a new island rises from the ocean floor.
The Beginning of Ocean Earthquakes
An ocean earthquake commonly occurs between 200 and 1,000 years. As the pressure of floating plates bouncing against a continental plate rises, the continental plate starts pushing back. This causes an ocean floor island to recede underwater until the pressure is too great. Finally, an earthquake occurs between the continental and island plates due to this pressure. The new island suddenly pops up from the ocean floor in a span of 15 to 30 minutes.
The Formation of an Imminent Tsunami
A tsunami is a large destructive sea wave produced by an earthquake or volcano that occurs on the ocean floor. The ocean floor must move vertically for a tsunami to occur. As the new island suddenly pops up, the force of this action creates a huge wave that travels great distances. Tsunami waves can be as high as 30 feet and can travel at speeds of up to 500 MPH. Tsunami waves can be as long as 120 miles.
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