1 - Akademi Sains Malaysia

22
Disember
2010
Compiled by KHAIRUNNISA SULAIMAN
Can humans
start an earthquake
I N May 2008, one of the deadliest earthquakes in history
struck Sichuan Province in western China, registered 7.9 on
the Richter scale, leaving a 298 kilometer cracking in the
Earth's crust and almost 80,000 people dead.
In the aftermath of the disaster, attention quickly turned to
a nearby dam, just 5.5 kilometers from the epicenter of the
earthquake.
Many scientists believe the Zipingpu Dam reservoir may
have helped trigger the massive quake.
But aren't earthquakes natural disasters The vibrations of
the earth's surface we call earthquakes are typically natural
occurrences.
They're most often caused by the shifting of plates of rock
under the surface of the earth. These plates move along fault
lines, which are places where
the otherwise solid
rock of the Earth's
crust has cracked.
When the plates
slide against each
other or away
from each other,
the earth vibrates
violently.
Earthquakes
are also caused by
natural occurrences
like volcanic
eruptions.
Vibrations felt
at the surface of the Earth can also result from earth-shaking,
man-made events like underground bomb testing and mine
collapses and the filling and emptying of dam reservoirs.
It's easy to see how an underground explosion can shake the
earth. A dam A dam is just holding back water. How can that
cause an earthquake
Most of us accept that our actions can have great effects on
our natural environment. In the case of triggering earthquakes,
we're talking about man's actions reaching deep underground,
all the way down to the crust.
Can we ever replace plastic
OUR lives are molded,
packaged and sealed
in plastic dependency.
Look around you
at your computers,
phones, water bottles
and credit cards.
Plastic components
pepper everything from
our automobiles to our
surgical implants. Our
children play with plastic
toys while we rip the
cellophane wrappers
off our prepackaged
dinners.
The downsides to plastic are certainly
no secret. For starters, it's often a nonbiodegradable,
petroleum-derived product.
When we factor in toxins, wildlife endangerment
and difficult recycling, and
esfiaofmg
the plastic industry has
quite a public relations
problem on its hands.
As much as the
sight of plastic-littered
landscapes and debrisstrewn
highways depresses
us, plastic is still
a highly attractive material.
Plastic manufacturing
only takes up five
percent of the world's
oil supplies and, in doing
so, provides us with
an exhaustive supply of material.
So what's a plastic-addicted civilization
to do A return to reliance on aluminum
and glass may seem attractive, but these
materials aren't as cheap, versatile or durable
as plastic.
Plastics first hit the scene in the second
half of the 19th century and eventually
became a top manufacturing material.
What will the next great human manufacturing
material be Interestingly
enough, the answer is more plastic.
Combustible, nonpetroleum plastics
will likely become more and more common
as researchers continue to find ways
of creating polymers from such organic
sources as corn, orange peel, bamboo, papermaking
byproducts and hemp.
While bioplastics will eventually provide
a clean, recyclable, nontoxic alternative,
energy and environmental analyst
Christopher Flavin, author of "The Future
of Synthetic Materials" insists that
oil-based plastics aren't going anywhere
just yet. He predicts that the next 20 years
will see bioplastics absorb a mere five percent
of the global plastic market.