EARTHQUAKES
Earthquakes are deadly disasters that affect many lives. Find out about
why earthquakes occur, what they do, their impact on wildlife and
communities and the design principles of an earthquake-proof building.
Report by
Douglas Joshi
1. What is an Earthquake?
Earthquakes are common natural disasters that affect many lives and occasionally destroy entire
cities.
Earthquakes originate from the ever-moving tectonic plates that make up the crust of the earth.
They don’t move easily; they catch onto each other. When finally they move past, an immense
amount of energy is released and the ground above will shake accordingly. There are three major
types of tectonic movement, depending on the geometry of the plate collision. The first is when they
slip past each other horizontally and is called a “strike-slip.” The second is when one plate is moving
downwards and is called a “normal.” Thirdly, there is a movement which involves one plate pushing
upwards and is called a “thrust.” Most earthquakes occur in the Ring of Fire in the Pacific Basin (e.g.
Japan, New Zealand, California) followed by the Alpide Belt across the southern edge of Eurasia (e.g
Italy and Nepal).
2. Measuring Earthquakes.
During an earthquake, the ground above will shake depending on the energy of the plate collision.
This energy can be measured using a seismograph which measures the amplitude of the seismic
waves (related to the energy release of the earthquake) and is recorded on a scale known as the
Richter scale. The Richter scale is a base-10 logarithmic scale, which means that a magnitude 3
earthquake would have amplitude 10 times that of a magnitude 2 earthquake and a magnitude 7
earthquake would have amplitude 100,000 times that of a magnitude 2. A magnitude 2 earthquake
would not be felt by people, but only by a seismograph. One measuring from 2 to 2.9 would be felt
by a few people but no damage to buildings would occur. If it measured between 3 and 3.9 it would
be felt by most and might noticeably shake some objects. One measuring from 4 to 4.9 may cause
minor damage to buildings and some objects inside may fall to the floor. When we reach 5 to 5.9
level, it may damage houses that are not designed to survive an earthquake; everyone would feel it.
From here on, the earthquakes are considered dangerous. In a 6 to 6.9, many buildings will be
damaged and there will be widespread shaking. Between 7 and 7.9, we would expect widespread
damage in most areas. From 8 – 8.9 there would be damage in large areas. In a worst nightmare
scenario, a 9 to 9.9 earthquake would result in severe damage to most buildings. Luckily, a
magnitude 10 earthquake has never hit before, but if it did, the result would be catastrophic.
3. Impact on Communities and Wildlife.
An earthquake measuring over magnitude 5 on the Richter scale may cause injuries and deaths. It
can destroy homes and vital infrastructure e.g. water supplies, gas and electricity supplies, and
sewerage pipes. This may bring deadly diseases with people forced to drink contaminated water in
order to survive. Earthquakes can destroy entire settlements, and can ruin economies. Earthquakes
can also trigger landslides which may kill even more than the original earthquake. An earthquake
beneath the sea may trigger a deadly tsunami (giant wave) affecting wildlife and island and coastal
dwelling people. Earthquakes may also release poisonous material from broken gas means and
industrial works into the atmosphere, killing many.
Earthquakes don’t kill people. Buildings do.
This is the Alpide Belt. This is the
next most common place to have an
earthquake, after the Ring of Fire.
Here are some types of tectonic
plate movement.
Earthquakes don’t kill people. Buildings do.
This is the Richter scale. This is what
scientists use to measure the power
of an earthquake.
This is the Ring of Fire. This is where
most earthquakes occur.
This is a graphic representation of
the Richter scale.
Earthquakes don’t kill people. Buildings do.
4. Design Principles for an Earthquake-Proof House.
Houses situated in earthquakes zones such as the Ring or Fire or the Alpide plate should be suitably
earthquake-proofed to survive. For the foundation, there should be at least six pillars. Each one
should have a steel core for strength and a concrete casing. Between the pillars there would need to
be springs and / or some sort of shock absorbent gel. This would give the house the ability to move
with the seismic waves rather than cracking and crumbling. Instead of glass, the windows should be
made of a flexible lightweight plastic since glass breaks easily and is then extremely dangerous. The
walls might be made of light steel sheeting, and the roof of profiled steel. A tiled roof would be
heavy and the tiles may fall on people. Walls should also have padding (e.g. gel or rubber) to absorb
shockwaves and to reduce the risk of injuries, and the floors could be made of plywood with
(optional) light carpet. Underneath the plywood there would be timber beams to support the floor.
Furniture must be low, or built into the wall. Tall furniture, e.g. wardrobes or cabinets may fall down
and become a potential weapon! There should be as many exits from the house as possible, to
reduce the risk of the occupants becoming trapped.
References:
http://www.ehow.com/info_8094968_effects-earthquake-environment.html
http://popupbackpacker.com/wp-content/uploads/2013/03/Richter-Scale.jpg
https://upload.wikimedia.org/wikipedia/commons/0/0e/Fault_types.png
https://upload.wikimedia.org/wikipedia/commons/thumb/5/52/Pacific_Ring_of_Fire.svg/20
00px-Pacific_Ring_of_Fire.svg.png
https://upload.wikimedia.org/wikipedia/commons/e/e1/Alpiner_Gebirgsg%C3%BCrtel.png
http://www.reidsteel.com/information/earthquake_resistant_building.htm
http://science.howstuffworks.com/engineering/structural/earthquake-resistantbuildings.htm
https://www.tech21.com/en_us/impactopedia/how-are-buildings-made-earthquake-proof
https://www.e-education.psu.edu/earth520/files/earth520/RichterScale.gif
Earthquakes don’t kill people. Buildings do.