The state of Tasmania in Australia has some pretty fascinating geology.
This includes unusual minerals such as the specimen I am holding which used to be part
of Earth's upper mantle and oceanic crust far below sea level but were uplifted onto
continental crust via what is known as an ophiolite.
With this being said, the state also has a unique geologic feature which few are aware
of, an impact crater so young that the depression in the ground it formed is still quite visible.
Although it has been infilled by more than 200 meters thick of sediment from a lake which
once existed here, what you are looking at is Darwin Crater, which once had a 230 meter
deep hole in the ground that was also 1200 meters or 3937 feet wide.
Despite its rather ancient appearance, the catastrophic formation of Darwin Crater only
dates to 816,000 years ago.
In the asteroid belt, a small asteroid had long ago formed during the early Solar System
4.55 billion years ago as grains of dust and small rock particles pulled together to form
a larger mass.
This asteroid did not change shape for the following 4 billion years, but this was about
to change.
By 816,000 years ago, the now 85 meter or 279 foot wide asteroid was orbiting the sun
at a distance of 257 million miles.
As this asteroid was moving, a chance close encounter was about to occur with a larger
object, which for the sake of this video we will assume was the 584 mile or 939 kilometer
wide dwarf planet known as Ceres.
The gravitational pull from this massive object on the small asteroid got stronger and stronger,
causing the small asteroid to curve around the dwarf planet, before being slingshot off
into the inner solar system.
Now on an eventual collision course with earth, the 1.1 million metric ton mass of rock accelerated
towards the orbital path of Earth.
Several months later, this chondrite asteroid entered the upper atmosphere of Earth, traveling
at a speed of 17 kilometers per second or 38,000 miles per hour.
Due to the friction generated, over the next few seconds it began to burn up, turning into
a bright fireball which traveled from east to west across the sky.
At an elevation of 50 kilometers, it began to break up into several smaller pieces.
Many of these smaller pieces in the next 4.15 seconds would explode in midair, creating
powerful shockwaves which would later knock over some trees on the ground.
A hundredth of a second later, the main fragment impacted the surface in an explosion equivalent
to the detonation of 4 million tons of TNT.
As a bright light was generated, a 3500 mile per hour wind raced outwards from the impact
site, which at a distance of 1500 meters away obliterated everything, with a force of 560
psi.
This blast wave would quickly dissipate but would be lethal to all organisms in a 7 kilometer
radius, as a 487 mile per hour wind destroyed everything in its path and even triggered
minor landslides.
Although humans would not inhabit Tasmania for another 780,000 years following the impact,
the following information is presented to display what effects the impact would have
had if all of today's structures existed at the time of the impact.
Expanding outwards to a distance of 15 kilometers, all trees were blown over facing outwards
from the impact site, and many structures would have collapsed to the side.
At 20 kilometers away, 30% of trees would fall as a 91.6 mile per hour shockwave hit.
Tree damage would occur to a distance of 30 kilometers, while all glass windows would
shatter to a distance of 35 kilometers.
In fact, at distances up to 250 kilometers away, if today's structures had existed at
the time, windows would shatter in select but not all buildings across almost the entirety
of Tasmania.
The magnitude 5.0 earthquake generated would be felt up to a distance of 300 kilometers
from the impact site.
As the blast wave traveled across the planet, it was audible to a distance of 6000 kilometers
allowing the sound of the impact to be heard as far away as on the island of Mindanao in
the Philippines, the Indonesian islands of Sulawesi and Java, and sections of Malaysia.
Due to the new crater representing a low point which dropped below the level of the region's
water table, it quickly filled with water to form a lake.
This lake would subsequently be filled in by 200 meters thick of sediment, causing the
lake to eventually disappear.
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