Newcastle Earthquake (Chapter 3.13 sample study)
The Newcastle earthquake of 1989 was the first Australian earthquake recorded to
claim lives, with a magnitude level of 5.6 it is classified as a moderate earthquake.
When: 10:29.00 am, 28th December 1989
Where: Newcastle, latitude: -32.946, longitude: 151.607
Event causation: The Earth’s outer layer is broken into many pieces called tectonic
plates. Earthquakes are caused when the tectonic plates rub, collide and slide on to each
other, breaking rocks and causing stresses deep within the earth.
There is much controversy about the causation of the Newcastle earthquake of 1989,
many claimed that the earthquake was a natural phenomenon although geoscientist,
Christian Klose of Columbia's Lamont-Doherty Earth Observatory, NY proposed that the
Earthquake was in fact man made. Christian’s theory states that a major fault beneath
Newcastle's coalfields had been reactivated after coal was removed and water was
pumped out to keep the mines dry and running. An estimated 500-mega tonnes of coal
and 2000-mega tonnes of water had been removed from under the earths crust,
changing the pressure and environment beneath the surface and causing the
reactivation of a major fault line. Many people still continue to argue the actual cause of
the event although no one knows.
This image explains how the pressure moving on the
fault plane forms earthquakes.
Immediate impact: The Newcastle
earthquake caused 13 deaths, hospitalised
over 160 people, demolished 300 buildings
and damaged over 50,000 (most of which
were homes). Over 300,000 people were
affected and 1000 were left homeless. As seen
in the image to the right, the earthquake was
felt kilometres away. This caused damage to
many things on the way, including natural
and manmade structures.
The above image is a map of NSW showing how intense the earthquake
was on the mercalli scale. Colour coded, you can see that Newcastle
reached a high of VII destructive and the earthquake could even be felt as
far away as Albury.
Cost to the community: The estimated damage bill was $4 billion, but for the
families of the people lost, no amount of money could replace their loved ones. The
buildings in Newcastle are now reinforced and fully supported.
QUESTIONS
1. How would you rate the Newcastle earthquake on the Modified
Mercalli scale? Give reasons for
your answer. I would rate the Newcastle
earthquake a VI because many houses were damaged and some older buildings
collapsed.
2. Why was there so much damage when the earthquake measured
only 5.6 on the Richter
scale? There was an underlying thin layer of silt and
sand covering a former course of the hunter river, which seemed to magnify the
shaking.
3. What were the main government responses to the Newcastle
earthquake? They now monitor seismic activity closely and all buildings are
now built to certain regulations