Geology Reference
In-Depth Information
heavily populated. The combination of these factors is what determines the damage and
death toll of an earthquake event.
The amount of damage resulting from an earthquake is related not only to its
strength and location but also to the type of structures it affects. In some regions,
such as the state of California, measures have been taken to construct buildings
that can withstand the occasional ground-shaking activity of earthquakes. As seen
in the 2010 earthquakes that affected Haiti and Pakistan, less modernized regions
may be devastated by an earthquake.
When earthquakes occur, they may initiate a phenomenon called
liquefaction.
Liquefac-
tion is when the shaking movement of the earthquake leads dry sediments (commonly
sand) to flow as if they are a liquid. The liquefaction of sediments by earthquakes can
result in all the damages associated with landslides.
Efforts to record and study earthquakes are designed to eventually predict them in
hopes of avoiding the destruction of property and loss of human life that often result
from earthquake activity.
Washing Away Coastal Towns: Tsunamis
Another hazard, a tsunami, is closely related to earthquakes and landslides. When either
of these two events occurs underwater, it creates a large wave that can travel hundreds
of miles an hour across the open ocean, washing ashore as a wall of water and rushing
miles inland. Sometimes incorrectly referred to as
tidal waves
(they have nothing to do
with the tides), these giant waves have been recorded in South America as a result of
earthquakes that occurred in Japan.
Similarly, offshore, undersea landslides can displace large amounts of water, sending the
water onshore with devastating outcomes. Coastal towns affected by landslide-gener-
ated tsunamis often have little to no warning.
Earthquakes do provide some warning that a tsunami may be on its way. If
you are near the coast and feel an earthquake, or if you see the water move far out
to sea, get to higher ground immediately. (The water often moves out, like a very
fast, low tide, before the large tsunami waves come ashore.)
