Impact Earth

ec1968

Jedi
http://www.purdue.edu/impactearth

New modelling site for determining the damage that various sized objects might do on impacting the earth.

Reported on the BBC News site thus:

Want to know what would happen if a 10km-wide asteroid came out of the sky and slammed down on your city?

Scientists at Purdue University and Imperial College London have updated their popular impact effects calculator first produced in 2004.

Users dial in details about the hypothetical impactor, like its diameter and density.

The web program then estimates the scale of the ensuing disaster, such as the size of the crater left behind.

It will also tell you how far away you need to be to avoid being buried by all the material thrown out by the blast, or set on fire.

The original calculator was a "big hit" when it was released, not just within the research community but with a curious public, also. Devised by Purdue's Professor Jay Melosh and colleagues, it is underpinned by scientifically accurate equations.

Many government organisations and scientific institutions regularly link to the calculator as an education tool.

The updated program, known as Impact: Earth! incorporates some additional impact effects, such as the tsunami wave height from an ocean collision. But the key difference those familiar with the old tool will notice is the much more visual and user-friendly interface.

"We've had to update things as knowledge has improved," said Imperial's Dr Gareth Collins.

"One of the major new additions is the estimates for tsunami wave height at a given distance away from an ocean impact. This had been a popular request, but we didn't put it in the original calculator because there simply wasn't consensus back then on what the hazard was. There's since been some good research and we now have a better understanding of the issue," he told BBC News.


The famous Barringer (Meteor) Crater in Arizona was dug out by a 40m-wide impactor
On average, an object about the size of car will enter the Earth's atmosphere once a year, producing a spectacular fireball in the sky.

About every 2,000 years or so, an object the size of a football field will impact the Earth, causing significant local damage.

And then, every few million years, a rock turns up that has a girth measured in kilometres. An impact from one of these can produce global effects.

"The site is intended for a broad global audience because an impact is an inevitable aspect of life on this planet and literally everyone on Earth should be interested," said Dr Melosh.

"There have been big impacts in the past, and we expect big impacts in the future. This site gives the lowdown on what happens when such an impact occurs."

Purdue servers host the new calculator; Imperial will continue to host the old web program. This is being retained for those internet users who do not have fast connections.

The Imperial site is also trialling a tool that will enable users to map the impact effects on to the virtual globe software Google Earth.

"When we first launched the calculator, we hoped it would be a useful tool for scientists working in the field and for those people who were simply keen to find out more when a new crater was discovered and they wanted to understand the consequences if that event had happened yesterday," recalled Dr Collins.

"So we thought there would be some curiosity, but we were simply blown away by the interest."
 
I just typed this data in :

Diameter: 10 000 km
Density: 8000 kg/m^3 for iron
Angle: 90 degrees
Velocity: 72 km/s
Target: Sedimentary Rock
Your Distance: 20000 km

Result:

Global Damages: The Earth is not strongly disturbed by the impact and loses negligible mass.
Depending on the direction and location the collision, the impact may make a significant change in the tilt of Earth's axis.
Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 4626.767 hours.The impact shifts the Earth's orbit noticeably.


:huh:

I'm not a scientist but even I know that this can't be right.

maybe the software is not disigned for an asteroid of this sice ?
 
Well everyone is always complaining how there are not enough hours in the day, it makes sense that having 4000+ extra hours every day would just make people happy, hence not a strong disturbance! I know I'd be able to catch up on all the reading for sure then. :P
 
Pashalis said:
I just typed this data in :

Diameter: 10 000 km
Density: 8000 kg/m^3 for iron
Angle: 90 degrees
Velocity: 72 km/s
Target: Sedimentary Rock
Your Distance: 20000 km

Result:

Global Damages: The Earth is not strongly disturbed by the impact and loses negligible mass.
Depending on the direction and location the collision, the impact may make a significant change in the tilt of Earth's axis.
Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 4626.767 hours.The impact shifts the Earth's orbit noticeably.


:huh:

I'm not a scientist but even I know that this can't be right.

maybe the software is not disigned for an asteroid of this sice ?

Perhaps the first line has to do with your distance from the impact - you put in 20,000 km - so perhaps the earth where you are isn't strongly disturbed? Not sure...
 
I tried it and placed myself only 5km from the impact and the message is the same. I think it means the planet. But my results were different given the same input variables, I wonder if they changed the calculation code?

Diameter: 10,000 km
Density: 8000 kg/m^3
Angle: 90 degrees
Velocity: 72km/s
Your distance: 5km

The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundredths of a degree).
Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 31.254 seconds.
The impact shifts the Earth's orbit noticeably.

I bolded the differences I got when compared to Pashalis's results. Weird. I re-ran it with a distance of 20,000km but still got my result.

It would be neat if we could tweak the parameters without retyping all of them to see how various variables change the outcome, like putting yourself closer or farther from the impact, etc.
 
Interesting. Maybe what we would mean by 'strongly disturbed by the impact' and what they mean are a lot different?
 
anart said:
Interesting. Maybe what we would mean by 'strongly disturbed by the impact' and what they mean are a lot different?
Right, like causing the length of a day to change by 31 seconds may very well be enough to trigger a global ice age or other cataclysm. But perhaps in their sense disturbance is more like how much a planet moves or something? But even that point is moot because it seems like that wording never changes. I sent a 50,000km in diameter piece of iron (the Earth itself is only 12,000km diameter!) at the planet at 45 degrees going 72km/s and it still didn't strongly disturb things, but we did gain 578,000+ extra hours in the day! I'd imagine the planet would be nothing but a pile of space dust after that one, there would be no "days" anymore.

Either their calculations are wrong, or most likely they're just limited. At some point fundamentally different changes happen than a linear or even exponential increase in numbers as the result of changing the variables. At some point the impact crater isn't just very big, because the planet blows up, etc. The model can't account for changes outside of what's "allowed" by the model, and definitely isn't aware of quantum shifts as a result of too much energy being added to a system, causing a fundamentally different reaction than simply a greater amount of the same stuff as before. That's why the global warming models are so hopelessly flawed - they just aren't aware of all the variables and how reality truly reacts to changing variables, nor are they even aware of the real cause-effect relationships between the variables involved, like whether cO2 causes warming or the other way around, etc.

Look at the link on their page for famous impacts. All those variables seem the same because it's just guesstimates cuz they don't really know, unless there's a cosmic factory pumping out standard-issue meteors somewhere.
 
The Earth is not strongly disturbed by the impact and loses negligible mass.

That seems odd. I would have thought the Earth would have gained mass with a 10,000 Km diamerter asteroid! Or skittled the Earth into the next solar system.

As a comparison, the Earth is 12,000 Km diameter, and the moon is only 3,476 Km diameter.
 
Pashalis said:
Global Damages: The Earth is not strongly disturbed by the impact and loses negligible mass.
Depending on the direction and location the collision, the impact may make a significant change in the tilt of Earth's axis.
Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 4626.767 hours.The impact shifts the Earth's orbit noticeably.

A change in the length of the day by 4626 hours is definitely more than "not strongly disturbed".

It's only the surface of the Earth that has to be affected for all hell to break loose. Not only that, but science these days isn't necessarily reliable when it comes to predicting what will happen if the axis tilts even a small amount.

Methinks this calculator is designed to put people's minds at ease!
 
What I didn't say in my original post was that I found the results of the test runs I made to be far from what I would have expected. I wanted to see other folks reactions first. I was a scientist once (degree in Physics from Queen's University in Belfast, and a Masters in Electron Micrscopy) but its that long ago I've forgotten most of it and I switched to biology not soon afterwards. But still, I feel that some of these modelling results are quite a bit off beam.

Another device to make us think that things aren't all that bad, perhaps?

Regards

Eúnan
 
It's not all soothing though - if you ask for impact results from a 20 km diameter ice comet that hits the ocean at 3000 m depth (average ocean depth) at a distance of 1500 km from your location you get :

"The impact-generated tsunami wave arrives approximately 2.43 hours after impact. Tsunami wave amplitude is between: 186 meters ( = 609 feet) and 371 meters ( = 1220 feet)."

Thermal radiation:
"Time for maximum radiation: 7.2 seconds after impact
Visible fireball radius: 148 km ( = 91.8 miles )
The fireball appears 22.4 times larger than the sun
Thermal Exposure: 3.09 x 10^8 Joules/m^2
Duration of Irradiation: 1.17 hours
Radiant flux (relative to the sun): 73.5


Effects of Thermal Radiation:
Clothing ignites.
Much of the body suffers third degree burns.
Newspaper ignites.
Plywood flames.
Deciduous trees ignite.
Grass ignites."

Seismic effects :
"The major seismic shaking will arrive approximately 5 minutes after impact.
Richter Scale Magnitude: 10.5 (This is greater than any earthquake in recorded history)
Mercalli Scale Intensity at a distance of 1500 km:
Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.
Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop."

Air blast :
"The air blast will arrive approximately 1.26 hours after impact.
Peak Overpressure: 295000 Pa = 2.95 bars = 41.9 psi
Max wind velocity: 370 m/s = 828 mph
Sound Intensity: 109 dB (May cause ear pain)

Damage Description:
Multistory wall-bearing buildings will collapse.
Wood frame buildings will almost completely collapse.
Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse.
Highway truss bridges will collapse.
Glass windows will shatter.
Up to 90 percent of trees blown down; remainder stripped of branches and leaves."
 
Pashalis said:
I just typed this data in :

Diameter: 10 000 km
Density: 8000 kg/m^3 for iron
Angle: 90 degrees
Velocity: 72 km/s
Target: Sedimentary Rock
Your Distance: 20000 km

Result:

Global Damages: The Earth is not strongly disturbed by the impact and loses negligible mass.
Depending on the direction and location the collision, the impact may make a significant change in the tilt of Earth's axis.
Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 4626.767 hours.The impact shifts the Earth's orbit noticeably.


:huh:

I'm not a scientist but even I know that this can't be right.

maybe the software is not designed for an asteroid of this sice ?

I think the calculations have since been adjusted. I came across this site today and using the same parameters as above get this result:


Global Damages: The Earth is completely disrupted by the impact and its debris forms a new asteroid belt orbiting the sun between Venus and Mars.
100 percent of the Earth is melted

The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundredths of a degree).
Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 31.3 seconds.
The impact shifts the Earth's orbit noticeably.

Perhaps an improvement in the maths & physics calculations, but I still think a 31 second change in the length of day is probably irrelevant when you're calling your new home an asteroid belt ;)
 
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