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CIVIL
DEFENCE -
EARTHQUAKES |
What is an Earthquake?
An earthquake is a sudden slipping or displacement
of part of the earths crust. When it happens, energy is released
and travels outwards in waves.
Can earthquakes be predicted?
World-wide attempts so far have produced limited success. China has been able to
predict one major earthquake and evacuate people in time. But China too has had
failures in successfully predicting an earthquake.
In New Zealand some progress has been achieved in recognising factors that may
precede an earthquake. However, the best answer for when the next major
earthquake will occur in New Zealand is "eventually".
How are earthquakes measured?
Earthquakes are measured by two scales. The first,
the Richter Scale, is one that measures energy at the epicentre. Each succeeding
unit on the Richter Scale is equivalent to 30 times the energy released by the
previous unit.
A shallow earthquake of magnitude 2 would hardly
cause any damage. An earthquake of magnitude 7 at the same depth is likely
to cause widespread damage. the Mercalli Scale is a 12
point scale of felt intensity or visual damage. This scale is more useful than
the Richter Scale in describing the impact of an earthquake.
Here are some examples of the scale:
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Mercalli I
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Not felt |
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Mercalli IV |
Felt indoors and may wake you up
at night |
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Mercalli Vl |
Felt by all some heavy
furniture may move |
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Mercalli Vlll
|
Some damage to weak buildings |
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Mercalli X |
Masonry destroyed landslides
will occur |
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Mercalli XII |
Total damage |
History of
earthquakes in New Zealand
Written records in New Zealand have existed for
major earthquakes since the 1843 earthquake near Wanganui. Prior to
that period, we must depend on oral history. One earthquake recorded
in oral history occurred in Wellington about 1460. That earthquake
helped to form the Miramar Peninsula. The earthquake was called "hao
whenua" the land swallower.
The largest earthquake on written record was the
1855 earthquake. It was centred on the Wairarapa fault line and
measured 8 on the Richter scale. That earthquake lifted land around
the Wellington coastline about 2 metres. Since that time there have
been many earthquakes which have caused major damage. Some examples
are shown in this pamphlet Murchison (1929), Napier (1931), Inangahua (1968)
and Bay of Plenty in 1987.
Some precautions you can take before
an earthquake occurs:
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DO Secure heavy furniture to the wall or floor.
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DO Place heavy items near the floor
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DO Put strong catches on cupboards to prevent
crockery falling out.
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DO Save water in containers. Store these
containers away from sunlight.
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DO Check that your chimney is secure. If
you are not sure, have a builder check and strengthen the chimney
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DO Secure your hot water cylinder. This
will help to lessen damage to the cylinder if your house moves during an
earthquake.
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DO
DEVELOP A FAMILY PLAN
Make sure everyone knows
how to survive an earthquake
where to get help if it is needed
how to make contact with other members of the family during a disaster.
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DO LEARN FIRST AID
Contact your local organisation of the Order of St John or the Red Cross
Society.
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DO Learn how to turn off
water, gas and electricity at the mains.
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DO Learn how to control
small fires small fires. Know how to escape from a fire.
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DO Check your survival kit
regularly. (See the pamphlet called "Your Disaster Survival Kit"
for further information.)
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DO Get to know your
neighbours. You all have skills and resources that will be vital in
a disaster.
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DO Know the location of
your nearest Civil Defence Centre.
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DO CHECK NOW that your
household insurance completely covers earthquake damage.
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DONT
Put chemical cleaner in the toilet cistern you
will poison a potential source of drinking water.
During an earthquake
STAY INSIDE
KEEP CALM give yourself time to think.
TAKE COVER
Get under a table. Hold onto it to prevent it moving away from you.
Crouch beside a solid structure. It may
well be a wall. Keep away from glass doors or windows.
Brace yourself in a doorway. Hold onto the door to prevent it
slamming into you.
Do not attempt to run outside you may be hit by falling masonry or glass.
If you are in a lift stop the lift at the nearest floor and get out.
DO NOT BECOME A CASUALTY. LOOK AFTER YOURSELF FIRST TAKE COVER AND BE A
SURVIVOR.
Outside in a High Rise area
Take cover in doorways.
Do not run into the street you may be struck by falling debris or power lines.
In
an open area:
Stay clear of high walls or power lines.
IF YOU ARE DRIVING slow down, pull over to the side of the road and stop the
car. Stay in the vehicle it will provide you with some cover.
After an earthquake
Check yourself and those around you for injuries .
Check your neighbours. Assist them if necessary. Make
sure that someone reports the damage in your area to the nearest Civil Defence
Centre.
Give first aid to those who need it. Make the injured comfortable
until help arrives.
Put out small fires. Evacuate the building if the fires cannot be
controlled.
TURN on your radio this will be your major source of information.
If your property is damaged take a note of damage to each item.
Keep all items until an insurance assessor has seen them.
DO NOT GO SIGHTSEEING.
Roads must be kept clear for emergency services.
If you are not directly affected by the earthquake.
DO NOT TRY TO GET INTO THE
AFFECTED AREA YOU WILL NOT BE
WELCOMED BY PEOPLE IN THE AREA
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