5 ms·

So, unless I missed it in there, how big of a crater is this gonna make?

by abacadaba 5y ago

T-A 5y ago
https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/ https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/
- dredmorbius 5y ago
  It'd be a pretty exciting day for anyone within 100km or so of the impact site. https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=100&diam=490&pdens=1190&pdens_select=0&vel=17&theta=45&tdens=1000&tdens_select=1500 https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?d... For a water impact, probably a high surf day for an even larger region.
dredmorbius 5y ago
Based on the calculator below, a final crater diameter of 7.39 km ( = 4.59 miles ), and final crater depth of 540 meters ( = 1770 feet ). I've run estimates of effects for selected distances from 1km to 1,000 km from impact. You'd probaby want to be at least 50 km minimum from ground zero. Strutural damage would be severe, though humans could survive There'd be substantial blast effects to 200 km, as well as ejecta. Nearer than 50 km, thermal and blast effects, as well as ejecta, would all likely be lethal. https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=200&diam=490&pdens=1190&pdens_select=0&vel=17&theta=45&tdens=1000&tdens_select=1500 https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?d...
- noahjk 5y ago
  Since you seem like you've the answer for this : what would it look like if it hit the ocean (both off a coast, in shallow water before a drop-off, and maybe way out in the middle of nowhere)? What if it hit Antarctica or somewhere on the north pole? Could it severely impact our ice reserves?
  - dredmorbius 5y ago
    I'm mostly just parroting what the impact calculator says. There's no estimation of tsunami impacts, though I'm pretty sure that if the asteroid did strike open water, there would be a large tsunami within at least some tens of kilometers. Note that for massive seismic tsunamis you're looking at vertical continental plate displacements of multiple meters across tens, hundreds, or thousands of kilometers, representing vastly greater energies than this impactor. An asteroid is a point displacement that would dissipate rapidly (square of distance, so that doubling distance reduces intensity by a factor of four), and comparatively small energies. The 2014 Indian Ocean earthquake and tsunami is estimated at about 26 MT equivalent, ten times greater than Bennu. It invovled a linear disruption along ~1,600 km (1,000 mi) of tectonic plate, of "several meters". Think of the difference between throwing a stone into water (meteor) and moving a board back and forth (tectonic plate). https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_a... You're looking at a similar situation for an ice impact. The latent heat of fusion of water is high, and the latent heat of vaporisation even higher. Paradoxically, the localised heating converting ice to steam at the impact point reduces the total melting effect. If the impact were at a critical point that would dislodge an attached ice shelf, there might be a widespread effect, but that's equivalent to placing explosives at a critical weak point of a structure. The direct heating received is equivalent to that recieved by sunlight falling over a period of 8 hours on a 370,000 km^2 area. That's somewhat less than the size of California. The total area of Antarctica is closer to 14 million km^2. It's a lot of energy, yes, but on the grand scheme of global warming, a small drop in the bucket. The energy is enough to melt 31.7 million tonnes (31.7 km^3) of ice, or to vapourise 4.7 millon tonnes (4.7 km^3) of water. (Note that you'd have to first melt and raise the temperature of that water.) A crater 1km deep and 31.7 km in area would have a radius of about 2.25 km. So yes, you'd punch a good-sized hole in the ice, but the net impact is small relative to Antarctica. Put another way, a large electrical generating plant (2 GW output) releases as much energy as the Hiroshima bomb did (15 kilotons TNT) ... in 9 hours. Both quantities and rates matter, as well as delivery mechanism. Providing 18 GWh to a city as electrical potential over the course of a workday is essential to its operation. Unleashing it as thermal pulse, blast, and radioactive effects in a few milliseconds is highly disruptive. Similarly, the Chelyabinsk meteor in 2013 was the equivalent of a rougly five hundred kT nuclear blast. That energy was released at a distance (roughly 20 miles / 32 km altitude), over time (several seconds), and in a form (mostly supersonic shockwave) that produced widespread damage on the ground (mostly broken windows and glass, some collapsed walls in weaker structures), but was not directly or indirectly lethal. https://en.wikipedia.org/wiki/Chelyabinsk_meteor https://en.wikipedia.org/wiki/Chelyabinsk_meteor

So, unless I missed it in there, how big of a crater is this gonna make?

T-A 5y ago

https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/ https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/

dredmorbius 5y ago
It'd be a pretty exciting day for anyone within 100km or so of the impact site. https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=100&diam=490&pdens=1190&pdens_select=0&vel=17&theta=45&tdens=1000&tdens_select=1500 https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?d... For a water impact, probably a high surf day for an even larger region.

dredmorbius 5y ago

Based on the calculator below, a final crater diameter of 7.39 km ( = 4.59 miles ), and final crater depth of 540 meters ( = 1770 feet ). I've run estimates of effects for selected distances from 1km to 1,000 km from impact. You'd probaby want to be at least 50 km minimum from ground zero. Strutural damage would be severe, though humans could survive There'd be substantial blast effects to 200 km, as well as ejecta. Nearer than 50 km, thermal and blast effects, as well as ejecta, would all likely be lethal. https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?dist=200&diam=490&pdens=1190&pdens_select=0&vel=17&theta=45&tdens=1000&tdens_select=1500 https://impact.ese.ic.ac.uk/ImpactEarth/cgi-bin/crater.cgi?d...

noahjk 5y ago
Since you seem like you've the answer for this : what would it look like if it hit the ocean (both off a coast, in shallow water before a drop-off, and maybe way out in the middle of nowhere)? What if it hit Antarctica or somewhere on the north pole? Could it severely impact our ice reserves?
- dredmorbius 5y ago
  I'm mostly just parroting what the impact calculator says. There's no estimation of tsunami impacts, though I'm pretty sure that if the asteroid did strike open water, there would be a large tsunami within at least some tens of kilometers. Note that for massive seismic tsunamis you're looking at vertical continental plate displacements of multiple meters across tens, hundreds, or thousands of kilometers, representing vastly greater energies than this impactor. An asteroid is a point displacement that would dissipate rapidly (square of distance, so that doubling distance reduces intensity by a factor of four), and comparatively small energies. The 2014 Indian Ocean earthquake and tsunami is estimated at about 26 MT equivalent, ten times greater than Bennu. It invovled a linear disruption along ~1,600 km (1,000 mi) of tectonic plate, of "several meters". Think of the difference between throwing a stone into water (meteor) and moving a board back and forth (tectonic plate). https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_a... You're looking at a similar situation for an ice impact. The latent heat of fusion of water is high, and the latent heat of vaporisation even higher. Paradoxically, the localised heating converting ice to steam at the impact point reduces the total melting effect. If the impact were at a critical point that would dislodge an attached ice shelf, there might be a widespread effect, but that's equivalent to placing explosives at a critical weak point of a structure. The direct heating received is equivalent to that recieved by sunlight falling over a period of 8 hours on a 370,000 km^2 area. That's somewhat less than the size of California. The total area of Antarctica is closer to 14 million km^2. It's a lot of energy, yes, but on the grand scheme of global warming, a small drop in the bucket. The energy is enough to melt 31.7 million tonnes (31.7 km^3) of ice, or to vapourise 4.7 millon tonnes (4.7 km^3) of water. (Note that you'd have to first melt and raise the temperature of that water.) A crater 1km deep and 31.7 km in area would have a radius of about 2.25 km. So yes, you'd punch a good-sized hole in the ice, but the net impact is small relative to Antarctica. Put another way, a large electrical generating plant (2 GW output) releases as much energy as the Hiroshima bomb did (15 kilotons TNT) ... in 9 hours. Both quantities and rates matter, as well as delivery mechanism. Providing 18 GWh to a city as electrical potential over the course of a workday is essential to its operation. Unleashing it as thermal pulse, blast, and radioactive effects in a few milliseconds is highly disruptive. Similarly, the Chelyabinsk meteor in 2013 was the equivalent of a rougly five hundred kT nuclear blast. That energy was released at a distance (roughly 20 miles / 32 km altitude), over time (several seconds), and in a form (mostly supersonic shockwave) that produced widespread damage on the ground (mostly broken windows and glass, some collapsed walls in weaker structures), but was not directly or indirectly lethal. https://en.wikipedia.org/wiki/Chelyabinsk_meteor https://en.wikipedia.org/wiki/Chelyabinsk_meteor