look out earthquake what should you do
during a big tremor this is Dan he
recently arrived in this country to
start a job suddenly his office starts
to shake and the building sways
violently Dan's from a country that
doesn't have earthquakes and he panics
luckily his co-worker Rena is there to
show him what to do first
get under a desk for protection if
there's time open a door to secure an
exit in a high-rise building tremors
could continue for 10 minutes or more
although the shaking may make you feel
sick the building is unlikely to
collapse so stay calm dan is impressed
by how cool Rena is but he wonders why
high-rise buildings sway with such long
movements Leiner explains the shaking
movement due to an earthquake is called
seismic ground motion the number of
seconds for each back-and-forth movement
is its period depending on the length of
the period the movement is either short
or long period ground motion too thick
of the grounds sedimentary layers the
longer the period because cities are
usually built on planes composed of very
thick sedimentary layers they often
experience long period ground motion
each building has its own period which
depends on the type of construction and
height higher buildings have longer
periods and these are more likely to be
the same as the ground motion when a
building's period is the same as that of
the ground
this causes resonance which greatly
magnifies the shaking that's why even
though the ground outside is only moving
slightly a tall building might be
shaking violently
dan now understands what's happening the
only reason desks and lockers don't move
is that they are all securely fastened
down after the shaking stops dan asks
Rena to lunch not so fast says Rena
don't assume it's safe to go outside so
quickly if you're near the sea or a
river a tsunami might be coming and
after a major tremor aftershocks make it
dangerous to be near damaged structures
older buildings or cliffs that might
collapse Rena tells Dan he should train
to be ready for an earthquake in
earthquake prone countries communities
hold disaster drills and many facilities
provide earthquake simulations the
latest facilities can simulate
earthquakes in high-rise buildings and
many other scenarios to find out what's
available in your area just look online
thanks to Rena Dan is now ready for life
in an earthquake zone the next weekend
he takes his family to an earthquake
simulator now they'll know exactly what
to do in a big quake to stay safe during
a major earthquake the most important
thing is knowledge official online
disaster mitigation sites provide all
the information you need
remember don't rush stay calm and help
others
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