Bus-sized asteroid strikes earth -- effects?

If an asteroid was roughly the size of a bus at the time it impacted the earth’s surface, what would be the effect? Let’s say it struck a good-sized city. What would that be like?

Asteroid impact effects calculator https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/

Make a big noise, blow out a bunch of windows.

May have a couple chunks hit at terminal velocity, not a good day for anyone unlucky enough to be under one.

Be talked about on the news for a few days, maybe a week or so.

If I’ve put the numbers in correctly, a bus-sized rock wouldn’t do much. Nearby windows would break and it would be about as loud as heavy traffic, but no widespread damage would occur (except for things actually hit by fragments (the asteroid would fragment in the atmosphere)).

Or: What @k9bfriender said…

Well, I meant that the asteroid was actually bus-size at the time that it struck the earth.

So, after it has burned up in the atmosphere and that is all that is left?

It would be difficult to have something that left a chunk that size, and not break into a bunch more pieces.

But, it still wouldn’t be traveling much over terminal velocity, which for a bus sized hunk of rock would be pretty good speed. Punching in some basic numbers gets me somewhere between 250-750 MPH.

So, not a good day for that city block, probably. Very little effect more than a couple hundred feet away outside of a pretty loud noise and broken windows.

Interesting! Thanks.

A pretty decent sized badaboom.

Somebody is gonna be late for school.

I’m going to disagree and say that something big enough to remain in one bus-sized chunk when it hits the ground (but would have started as the size of multiple buses, and probably iron) is still going to be carrying much of its orbital velocity. In which case, the impact would be significant.

Even small stony meteorites can hit with cosmic velocity if the conditions are right. Concider Carancas in 2007. The original meteoroid was maybe kitchen table sized when it entered the atmosphere. I don’t know how big it was when it hit the ground, but less than a pound of material was ever found after extensive searching. Almost certainly it was smaller than a breadbox. It hit the ground going around 10,000 to 15,000 miles an hour and made a crater more than 40 feet across.

Sikhote-Alin was far below bus-sized when it stopped ablating and it shattered into shrapnel that slowed to terminal velocity in the atmosphere, but it still made more than 100 craters, the largest one more than 100 feet across.

So bus-sized when reaching the ground, I’m going to guess a speed measured in thousands of miles per hour and a crater diameter of a couple of thousand feet. Kill radius from overpressure and shrapnel? Another guess but I wouldn’t want to be within a couple of miles at least.

I suppose it helps if the object is solid and dense, maybe a highly homogeneous lump of iron. Coming in at a steep angle so it does not cross a lot of atmosphere.

Meteor Crater in Arizona is attributed to an iron impactor 30 to 50 meters in diameter, which by square/cube law would make for considerably more mass than something bus-sized (most standard buses are roughly 13 meters long). Estimated by that writer as equivalent to a 20-40 MT nuke. Considering that we have seen in practice what even 0.2 MT can do, yeah, you don’t want to be anywhere near there when something that size hits at still-astronomical speed, either.

The largest fragment of the Campo del Cielo impact field, the Gencedo meteorite, I would say is about 1/10 - 1/20 of a “bus size”. The biggest crater from that impact field is 115x91 m. I don’t know if that largest fragment found made the largest crater, but several other craters there are > 50m across. And those meteorites impacted in thick loess, not hard ground, which is not generally where most cities are built.

Suffice to say, I think it will be a bad day for more than a few city blocks. Square-cube law being what it is, as mentioned, is gonna mean a bad day for pretty much the whole city, I think.

Making a rough estimate, I’d say that if every known meteorite on Earth couldn’t fit inside the volume of one bus/shipping container, then they could definitely fit in two.

What would happen if it hit the middle of the ocean? Or, close to shore? Or the middle of a Great Lake? Would it create damaging waves? Maybe if it were close enough to shore to hit bottom with plenty of energy it would cause problems?

An ocean impact could be a lot more devastating than a land impact. Envision if you will that bus-sized chunk of iron landing in the North Sea. In addition, I think all that vaporized sea water and sea floor getting pitched into the atmosphere would do a number on climate change.

Nah. Way too small to much notice in a large body of water.

The Chelyabinsk meteor that exploded over Russia in 2013 was about the size of a bus (20 m or 66 feet). It made a loud bang, blew out a bunch of windows and scared the crap out of a lot of Russians.

I guess it would need to be a bit bigger to still be bus-sized when it struck the Earth, but I imagine if it did, it would be like a small atom bomb.

Due to its high velocity and shallow angle of atmospheric entry, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.5 mi; 97,000 ft)

One would think had it entered the atmosphere at a much more direct angle …

It still would have blown up in the air, but probably closer to the ground. The thing is, most asteroids are loose conglomerations of rock with all kinds of internal voids and fractures. That comes from the fact that they’ve been playing a mean game of bumpercars out there for billions of years. So it makes them rather fragile and the stresses of entering the atmosphere are enough to cause them to self-desctruct. There are some made of nickel-iron and those are less fragile. But only a small fraction of rocks are nickel-iron.