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According to a recent study by by Christian D. Klose of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York, the most damaging earthquake in Australia’s history was caused by humans. The magnitude-5.6 quake that struck Newcastle, in New South Wales, on December 28, 1989, killed 13 people, injured 160, and caused 3.5 billion U.S. dollars worth of damage.
According to researchers that quake was caused by the changes in the earth caused by 200 years of underground coal mining. This intensity of the quake wasn’t enormous, but considering that Australia isn’t actually a seismically active place, it came as a surprise.
Over Burdening the Earth

The extraction of many millions of tons of coal from the area caused stress underground and triggered the Newcastle quake.
There has also been a significant amount of water being extracted along with the coal and this water is pumped out to avoid the flooding of these mines. For every ton of coal that is extracted around 4.3 times more water is extracted.

Quakes Caused by Humans

Coal mining is not the only reason why the earthquaakes are triggered. They are also caused by the construction of reservoirs and the production of oil and natural gas as well. Three of the largest human-caused earthquakes of all time were a trio that occurred in Uzbekistan’s Gazli natural gas field between 1976 and 1984

Each of the three had a magnitude greater than 6.8, and the largest had a magnitude of 7.3. Human-triggered earthquakes are very dangerous, especially in places that are not prone to earth quakes. this is because people in such areas are not prepared for the worst.

The ancient birds had flight feathers on its legs as well that allowed them to use their hindlimbs as an extra pair of wings according to a recent finding.

These feathers on their hind legs can be explained because they substantiate a theory that birds first used to just glide from the trees before flying in a full fledged manner. This paper puts across stronger evidence that birds were into gliding like the flying squirrels.

Where is the Link?

The Archaeopteryx was a dinosaur that survived about 150 million years ago. This looked more like a cross between a bird and a dinosaur. It had feathers and a wishbone like birds but also had reptile features like a long bony tail, claws and even teeth.

The specimens of Archaeopteryx discovered showed some curious features like long feathers covering its hindlimbs. For a long time many scientists dismissed the feathers on its hind legs as unusual looking, contour feathers that did not play any important role in the flight of the bird.

Four Wings?

After this it was futhur investegated and they found that the feathers found on the hind limbs of the Archaeopteryx had similar features of the flight feathers in modern birds. they also had the curved shafts, and a self-stabilizing overlap pattern and vane asymmetry. It was also found that the hind limb feathers would have allowed Archaeopteryx to fly slower and to make sharper turns.

There is also much speculation that the hind limbs were also used to perform other roles in addition to flight. Like the modern day pigeons, kittiwakes and vultures, the hindlimb feathers might have acted as airbrakes, or even stabilizers.

Scientists still exactly don’t know when in this evolutionary change from a “four winged” design to a two-wing one happened. But many of them believe that hindlimb wings were sacrificed so that the bids could use them for other functions like running, swimming and even catching prey.