[thedoc (OP)]

I was wondering what the short and long term difference would be if a significant (i.e. dinosaur killing) meteor/asteroid were to impact Earth in either:
1- land mass
2- deep ocean
3- polar ice cap

It would seem that each would have different materials ejected, displaced. Would one of them be "better" than the others?
Asked by Mike, USA

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[thedoc (OP)]

We put this to Heather Jackson, National Museum of Wales

[img float=right]http://www.thenakedscientists.com/forum/copies/RTEmagicC_951_Gaspra_01.jpg.jpg[/img]If you imagine the size of this potential asteroid it’s perhaps ten kilometres across, similar to the one which fell in Mexico 65 million years ago. Wherever it hits it’s going to be incredibly destructive. The most devastating impact is likely to be in the ocean because it potentially could cause tsunamis and the least destructive would be if it were to hit a poorly populated area, perhaps like Antarctica. The size of this object is something the size of Cardiff travelling at 25 times the speed of sound the compressed column of air travelling in front of it would heat the ground to almost as hot as  the surface of the sun. The blast wave would kill anything within about 250km instantly. The real killer would be the atmospheric effects that would be caused by the vaporisation of rock, particularly if that rock contained large amounts of sulphur because that could lead to severe acid rain. Predictions as to the size of the waves produced if it fell in the ocean vary but it’s clear that a large impact would drown coastal areas, which is where most of our population live. The pacific coast of Asia is a particularly deadly place for an asteroid to strike because of the population density there and the potential for tsunamis. Overall the worst effect would be caused by a meteorite falling into an ocean; perhaps not particularly deep, about 2km deep, causing a tsunami and then vaporising sea bed sediments which contain a lot of carbon dioxide and a lot of sulphur which would cause climate change for years to come.

[Madidus_Scientia]

Even the ocean would not provide any significant shielding of an asteroid that big, and the tidal waves would reach just about everywhere. I'd say none of the above

[Ethos]

I'll take a stab at the answer and say Antarctica, smack dab in the middle of it!

[turnipsock]

wouldn't the Sahara be the best place, loads of sand to absorb the impact and not many people will die?

[Madidus_Scientia]

The sand on the surface will be insignificant, the asteroid will penetrate so deeply that the debri thrown into the air will block out the sun

My secret underwater city that is nuclear and geothermally powered and self-sustaining would be pretty safe though I reckon

[techmatt]

I think that none of them would be good. However, I think the ocean would be the best place. Sure the tidal [tsunami] wave would destroy most of the cost areas and that much water in the atmosphere would probably be bad as well. Might get some rain in the deserts. I do believe the this would cause the least amount of damage from all the rest.

With the speeds in question the water would not offer much in the way of padding for the impact. It would still offer more padding then solid bedrock.

[chris]

I think a significant strike is bad news wherever it occurs...the problem is the ejected material. Hitting any surface will fragment the impactor as well as eject material from the impacted site. Hitting the sea is bad news, I believe, because the water thrown up into the atmosphere creates a huge greenhouse effect, cooking the Earth into submission.

Chris

[Raghavendra]

3. polar ice cap...
     It's the safest place, where asteriod can it... And we can't say that there is safest place on earth, we should also estimate there size.... If the size is bigger then cosmic collison takes place....

[Yomi]

Deep ocean i think

 but The Martian underground was safe place for early life

[Raghavendra]

Size should be smaller so that the waves that travels when asteriod fall on earth... if it's bigger in size... whole city can be destroyed

[Madidus_Scientia]

3. polar ice cap...
     It's the safest place, where asteriod can it... And we can't say that there is safest place on earth, we should also estimate there size.... If the size is bigger then cosmic collison takes place....

why?

[Yomi]

size matter but what really matters is the momentum its mass and the position of the fall and the amount of the impact to the ground didn't you see the examples of dinos who were completely vanished

[Raghavendra]

because there waves travel 360 degree when it hits the ground, Now consider when an asteriod hits ice caps like "antartica" the energy or waves of the asteriod is impossible to travel...

    Asteriod should fall on Ice beds.... not on the layer of ice....

[Chemistry4me]

because there waves travel 360 degree when it hits the ground,

What!?

[Yomi]

because there waves travel 360 degree when it hits the ground,

What!?

what

3. polar ice cap...
     It's the safest place, where asteriod can it... And we can't say that there is safest place on earth, we should also estimate there size.... If the size is bigger then cosmic collison takes place....

why?

because there waves travel 360 degree when it hits the ground,

How is this happening 360 degrees LOL >>>>>.....

[Raghavendra]

 Ya...  360 degree, the vibration causes distruction

[Madidus_Scientia]

Raghavendra I know english isn't your first language but most things you say make little to no sense

[Raghavendra]

OK

[thedoc (OP)]

Did we mention your answer on air?  Listen to the answer to this question on our podcast to find out...

[Sam Hill]

Don't worry the quantum formation of your brain means you will survive until you reach the maximum statistical probility of surival available in the current universe. This means whatever you do you will never be in situation where this arrises. But you have died numerous times already ,so don't worry about it, your used to it. And at the momment that age is about 130.

[Keebler Elf]

Personally, I believe that t North Africa also known as the Sahara Desert would be the ideal place for an asteroid of this hypothetical magnitude to hit earth. Antarctica would be a very bad idea. This is because if an impact were to take place there, trillions of metric tons of ice would be instantly vaporized, in turn causing the formation of storms of epic proportions, all the while the rest of melted ice would create tsunamis of their own. This is due to the amount of water that would be released by Antarctica’s melted ice sheets into the oceans (About 2.0% of Earth’s water is frozen down there or 70% of all the fresh water on Earth). The ideal place would have to be a low populated area that is dry.
On a further note…
 And since no one has mentioned it as of yet. I was thinking that mountains might be a good place for an asteroid to hit not only because they are lowly populated but also because of their high elevation (Let’s just say, in the middle of the Himalayas). This could perhaps allow debris to be thrown far enough pass our atmosphere where it would not be pulled back in by Earth's gravity (Less distance for the debris to reach space). This would cause less heat by the debris re-entry into Earth’s upper atmosphere.  All this debris would be the equivalent of billions of small asteroids hitting the Earth all at the same time inevitably causing Earth’s overall atmospheric temperature to increase, creating an “oven effect”. Though if blasted far enough and with the help of higher elevation this would cause less of an “oven effect” while also causing less future acid rain AND since this is a hypothetical perhaps some of the debris blasted up by the asteroid  that went far and fast enough created a small ring that orbits Earth.  (Like a smaller version of Saturn’s rings) At least it would give the Moon some company…  

[Keebler Elf]

Sorry, I did not mean to double post just then! I started registering in the middle of writing the above response...

Probably not the best circmstance to introduce myself but what the heck...  []

Well, hey everyone I look forward to meeting with you all! Just call me Keebs...

[litespeed]

There is no safe place for the asteroid. It would suffer roughly the same demise where ever the impact.

[Charlotte]

It's ridiculous to speculate. (1) We don't know where it will hit (2) That large, it will destroy everything while blocking the sun with debris.

[Menno]

No matter where it hits it is bad for everyone but if it hit where are the best places to live? I'm up in the rocky mountains good or bad?

[Tyro Abecedarian]

Antarctica has a lot of nasty issues as well, the vapourisation of billions of tonnes of ice, the fracturing of the rest of the ice would lead to a potentially large scale shedding of the glaciers. The steam and water clouds released from that alone would create a barrier to the sunlight for years, potentially leading to a mini ice age. however, should the impact be just right, it could trigger a volcanic event opening a chain of Volcanoes radiating from Mt. Erebus. The resulting super volcano would likely melt the remaining ice sheets and either way, a very sudden and lethal global flood. Add to that the usual fallout from large scale vulcanism. earthquakes, potentially unzipping the pacific ring of fire if the tectonic forces combine. Toxic gasses, a climate that would block the sun and...well, let's just say it would be a pretty bad day for us all. I dare say even the cockroaches wouldn't be doing exceptionally well