300 decibels or so, according to this: http://makeitlouder.com/Decibel%20Level%20Chart.txt
But, as der Trihs says, loudness stops having much meaning at that scale.
How about if it hit the Arctic Ocean? Most of the tsunami should be in unpopulated areas, except for the north of Britain and Scandanavia.
If it hit in the Arctic, wouldn’t what’s left of the polar ice cap absorb much of the energy?
If it does, that makes the effects worse. The more energy that gets absorbed, the less gets radiated/blown back into space where it’ll do no harm.
I don’t have a cite but I have heard that when this was calculated, even a “small” asteroid (less than one kilometer) would cause a wave of 1 000 meters high - not only hundreds of meters, but a thousand! - which means that not only the coastal areas themselves (meaning millions of people) but everything not on the mountains would be swept away. The Appalachians, for example, wouldn’t be high enough, only the Rockies.
Not that fleeing there would help much: the gale-force winds caused by the massive air turbulence (from the heat wave) would knock everything and everybody down (this goes for land impact, oot, presumably), and the atmosphere would need more than a couple of hours to calm down again.
So if you want to consider how to best survive, we need lots of time beforehand, to build concrete shelters in the mountains, and stockpile food, and build water tanks with algae powered by geothermal heat, so people will have protein to eat while the nuclear winter from the debris in the atmosphere lasts. And you need a lot of time to orderly evacuate people, because otherwise a handful of rich who can afford the above preparations will prepare themselves, the military brass will hide in the Colorado NORAD mountain, and the rest will be screwed.
Actually, I wonder if psychologists and sociologists are considering the question of how to deal with near-doom scenario. I hope that some astronomers and some NASA people are working on how to detect asteroids early and how to head them off (with 20 years of warning time, a course change of a couple of degrees is enough to miss Earth, something that our engines today should be able to achieve. While it’s not as cool as Bruce Willis blwoing things up, it would work).
Because if there’s too short a time left - say a couple of weeks or months - panic would ensue and civilsation break down. Even the rich couldn’t get their bunkers built and stockpile enough food if money isn’t worth anything because of the collapse of everything.
But would one or two years be better? Would people - giving past behaviour of goernments - believe that the governments have a plan for everybody, or that a lot of people won’t have room, but will be lied to keep calm? Because if they start suspecting they are being lied to - regardless of whether or not they really are - then there will be rioting. The poor countries, whose governments can’t afford to build enough shelters and stockpile food for even a small part of their population, might start wars with the neighbours to get their stuff.
What if it’s 10 or 20 years - enough time to build bunkers for every person in the world, even in the poor countries? Would the rich countries step in? (Not likely seeing how today they leave the poor countries hanging in the wind). Maybe they will do it to prevent wars and mass refugees.
Will people get used to the doom scenario and it will become old hat? Humans can’t live in a state of constant fear, the nerves and body can’t handle that. You get used to it or go bonkers.
Would people react the way they react to climate change now - that’s a long time off, why should we act now, that’s a lot of money to be spent, let other politicans worry about that?
A lot of SF stories about a planet with an impending catastrophe have a lottery when there’s not enough time to build space ships for everybody, but I have a hard time believing that people would submit quietly and that no manipulation would occur.
Of course, in no way am I advocating that tired old clichee where the top guys know about a catastrophe (or aliens on Earth, or sth. similar shocking) and decide to keep the information away from the normal people because they would panic and couldn’t handle it. That’s elitism and disdain of the worst sort, and profoundly undemocratic, shedding a bad light on the attitudes of the script writers / Hollywood execs who continue using this trope no matter how absurd, insulting and harmful (e.g. on Lost) it is.
Question: I think in the Apollo 13 movie or a similar one, they said that there’s a narrow angle the shuttle/ space ship has to hit in order to enter the atmosphere; if the angle is outside, the shuttle will be bounced off the atmosphere like from trampoline instead.
Now, an asteroid will have more mass and come hurtling with more kinetic energy than the shuttle itself, but still: could we put a structure into orbit as last-minute measure that could deflect the asteroid?
What if we just change a few degrees, and instead of falling straight down, the asteroid enters orbit - would a dozen rounds through the atmosphere burn off enough mass to make it less dangerous?
Are you sure? If the vaporised water/land is going to cause global cooling, then it seems like the (ant)arctic is the best place for it to land.
There are very few people there, so the immediate consequences would be lower. There’s a lot of ice there, which has to go through two phase changes to get to vapor, so there would be (relatively) less stuff in the atmosphere, since more of the energy would be absorbed in the transition from ice to water, and there aren’t (that I know of) major pole-to-pole wind currents, meaning that what did get thrown into the air would stay localized longer, and might not affect the global climate as much.
That’s just for a safe return. If they had entered at too shallow an angle, they’d have skipped off like a stone off the surface of a pond, but if they entered too steeply, they’d have entered the atmosphere without bouncing, but then have splatted on the landing. Here, it’s precisely the splat that we’re worried about.
The whole point is that we don’t want that energy entering the atmosphere. Whether the energy comes in suddenly in a fraction-of-a-second impact or over a span of hours in the upper atmosphere makes very little difference. Which is largely irrelevant: An atmospheric-assisted capture like that would be a fair bit harder than just generating a complete miss in the first place.
I vote that we shoot members of Aerosmith at any asteroids predicted to approach dangerously close to Earth.