Ask A Scientist© Environmental Earth Science Archive

name         Dustin Wayne R.
status       student
age          14

Question -   How do you make a earthquake proof building?
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It is impossible to make a building one-hundred percent earthquake proof.  In
the very strongest earthquake, even the best engineered building will suffer
severe damage.  However, engineers do their best to make sure the building
will stand up long enough for the occupants to get out to safety.

 From a simplistic standpoint, an earthquake places a sideways load on a
building.  So, in addition to making a building (or bridge or any other
structure) capable of holding up forces from gravity caused by the weight of
the structure and its contents, an earthquake resistant structure can
withstand a considerable sideways force.  This is done by tying the walls,
floor, roof, and foundations into a rigid box.

The worst buildings, from an earthquake standpoint, are made of unreinforced
masonry such as brick or concrete block.  Generally, the walls are made of
bricks stacked on top of each other and held with mortar.  The roof is then
made of beams of wood or steel laid across the top of the wall.  The roof's
weight is carried straight down through the wall to the foundations.  When
this type of building gets a sideways jolt, the masonry walls tip over or
crumble and the roof falls in on the unfortunate occupants like a house of
cards.  Since this type of structure is prevalent in poorer countries, the
death toll from earthquakes can be many, many times higher than in places
with strict building codes, such as Japan and California.

As the buildings get bigger and taller, the challenge becomes more
difficult.  The harmonic characteristics of the building and ground have to
be considered.  For instance, even if the building is very, very strong, the
foundations can settle or fail and the building will sink or tip over.  A
classic example occurred during a 1964 earthquake in Niigata, Japan.  The
Kawagishi-cho apartment buildings toppled over like a series of dominos.
The buildings themselves were so super strong that they were still intact,
but their foundations failed.  Although 2000 homes were destroyed, only 28
people perished in that earthquake.  So, the building codes undoubted saved
many lives.  Go the following web site to see some pictures:

http://www.ce.washington.edu/~liquefaction/html/quakes/niigata/niigata.html

If you are interested in earthquake engineering, this site has a number of
links to other earthquake oriented sites, too.

Andy Johnson
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