Download The Shaking Ocean Floor

The Shaking Ocean Floor
The Shaking Ocean Floor
When you think of an earthquake, what comes to
mind? Most people think about earthquakes on
land. They think of the ones that cause buildings to
collapse and roads to split apart. Did you know
that some earthquakes happen on the floor of the
ocean? These earthquakes can produce a series of
waves called a tsunami. Big earthquakes make
larger waves. The waves are very long, and they
can travel very quickly.
So what exactly causes earthquakes on the ocean
floor? Earth’s crust is like a puzzle. It is made of
many pieces that are always moving. The pieces
are called plates.
The map shows Earth’s major plates.
When one of these plates moves suddenly, the movement causes an
earthquake, which we can feel as a shaking of the ground.
Most earthquakes, including ones on the ocean floor, happen at the
plate boundaries where different plates interact.
A lot of people think all tsunamis are really tall. But remember,
tsunamis are different sizes depending on the strength of the
earthquake that causes them. In a deep ocean, a tsunami may be
greater than 100 kilometers long, but less then 1 meter tall.
But when a tsunami is close to a shore, the wave slows down.
This causes the wave to grow. A tsunami may be as tall as 25 meters
when it reaches a shore.
When a tsunami hits land, it can destroy everything in its path.
In 2004, the deadliest tsunami ever recorded hit the shores in parts
of Asia. It was triggered by a major earthquake beneath the Indian
Ocean. Years later, the area is still recovering from the damage
caused by the tsunami.
Scientists have developed a warning system to help protect people
from larger, more dangerous tsunamis that come onto land.
The system consists of two parts. First, a series of sensors detect the
underwater earthquake. Then, a warning is sent out so people can
leave the area. A warning system, if working properly, can often
save many lives.
Discovery Education Science
© 2007 Discovery Communications, LLC