California is one of the most active earthquake areas in the world.
It is know for the constant activity that occurs along the coast. As seen
on this map, the west coast is the most active area in the United States.
It is also the most intense, as seen by the red color indicators on the
map. Now the Earth is made up of layers, both liquid and solid. The layer
of crust and upper mantle is called the lithosphere. Below this is
a partly fluid layer, the asthenosphere, on which the plates move. These
plates cover large areas, usually meeting at continental and ocean boundaries.
The boundaries where plates meet are usually huge fault zones. The plates
can move laterally past each other, diverging or converging, causing much
seismic activity. The city of San Francisco lies on one
of these faults, the San Andreas fault that runs north and south through
California. This fault is capable of generating massive earthquakes. An
earthquake is caused by the breaking and shifting of rock beneath the surface
along these faults. It can also be caused by underground volcanic forces.
In San Francisco, the shifting of rock produces seismic waves. These waves
move through the ground and cause the shaking and trembling on the surface.
This effect causes the damage of fallen building, bridges, freeway overpasses. It also causes broken gas and water mains which causes fires and prevent
water from aiding in the fight. This damage has caused many deaths and millions
of dollars in repairs.Through predictions and warning systems,
seismologists are able to predict earthquakes to some extent. By making
your home or office earthquake-proof, one increases safety even in a seismic
hotspot.
Below this is
a partly fluid layer, the asthenosphere, on which the plates move. These
plates cover large areas, usually meeting at continental and ocean boundaries.
The boundaries where plates meet are usually huge fault zones. The plates
can move laterally past each other, diverging or converging, causing much
seismic activity. 
The city of San Francisco lies on one
of these faults, the San Andreas fault that runs north and south through
California. This fault is capable of generating massive earthquakes. An
earthquake is caused by the breaking and shifting of rock beneath the surface
along these faults. It can also be caused by underground volcanic forces.
In San Francisco, the shifting of rock produces seismic waves. These waves
move through the ground and cause the shaking and trembling on the surface.
This effect causes the damage of fallen building, bridges, freeway overpasses.
It also causes broken gas and water mains which causes fires and prevent
water from aiding in the fight. This damage has caused many deaths and millions
of dollars in repairs.
Through predictions and warning systems,
seismologists are able to predict earthquakes to some extent. By making
your home or office earthquake-proof, one increases safety even in a seismic
hotspot.
