Killing Earth with a cosmic flashlight

[AmoebaMan]

I'll start by saying that there are a number of other sub forums that this would be applicable to, but this seems the most appropriate.

I'm a engineer by trade, but I've been doing some creative writing lately, and for an idea I'm working on I'd like to hit my hypothetical Earth with a gamma ray burst. For those of you who don't know, a GRB is a cosmic phenomenon where something big happens (like two neutron stars colliding) and a large--and incredibly powerful--collimated beam of high-intensity radiation is shot forth across the universe. In the event that it somehow manages to strike Earth head on (odds probably similar to scoring a bullseye with a dart on a target across the Atlantic), science predicts lots of nasty things to happen.

For the sake of the narrative, I'd like to ignore those odds, and talk about what kind of consequences could be reasonably expected, both immediately and in the near and distant future, if Earth were to get nailed by one of these suckers. I want to make sure that I've got the facts as correct as possible. The desired end-state is basically the worldwide destruction of civilization, but not the extinction of humanity. I want to knock mankind down, but not out.

I've done some research on my own, and this is what I've come up with:

• All orbital installations on the day side of the blast would be wiped out, notably including GPS and satellite telecommunications.
• Fatal irradiation of all organisms on the day side of the blast, except those deep under ground or water, or in shielded bunkers.
• Massive depletion of the ozone layer on the day side of the blast, which would gradually even out over time and leave the entire Earth much more vulnerable to solar radiation.
• Copious generation of atmospheric nitrogen dioxide, which would lead to heavy photochemical smog (and subsequent global cooling) and acidification of rainfall.
• Unsure: gamma-rays from a GRB would presumably interact with molecules in the atmosphere similarly to gamma-rays produced by high-altitude nuclear explosions (which cause EMPs)--this might cause a powerful electromagnetic disturbance that could destroy all significant electronics on the day side of the burst (in case anybody survived to try to use them).
• Really unsure: I did this research a while ago, and it seems at the time I was under the impression that vivid aurorae would be involved on the day side of the burst. I've subsequently been unable to find justification for that belief. Can somebody set me straight?

What I'm also interested in (aside from what I'm wrong about and what else I've missed) is how one would go about surviving the aftermath. Is it believable that something like this could happen with enough potency to annihilate half of the world and civilization, but still leave the other half habitable enough. Like I said, I'm trying to destroy civilization, not drive humanity to extinction.

Thoughts? How can I improve the realism of this scenario? Or am I crazy for even trying? I'm willing to bend the rules a little, but I'd like to do so as little as possible.

 

[jedishrfu]

Perhaps you could have it hit in the Pacific Ocean or have it be very focused for a limited time zapping only select lands or water. The intensity might cause landslides that lead to tsunamis or that lead to other recurrent disasters.

The book Earth Abides starts off with the premise that everyone except a select few die from some pandemic. The cities are emptied, things fall into disarray, electrical grid fails, water system stops flowing various plagues of bugs, then rats then... Occur as the predators are removed from the scene...

http://en.m.wikipedia.org/wiki/Earth_Abides

 

[AmoebaMan]

Petitioning mods to move this back to some sort of real scientific forum. I'm not looking for sci-fi discussion, I want real scientific answers about a real scientific phenomenon. Editing the OP now to remove any hint of fiction.

EDIT: Never mind, I guess I can't edit the OP...

 

[Czcibor]

Fatal irradiation of all organisms on the day side of the blast, except those deep under ground or water, or in shielded bunkers.

Miners can also survive. Or kids kept in sanatorium underground.

I wonder however about one more thing - what with waste heat. I mean:

Air halving thickness:
150 m
http://en.wikipedia.org/wiki/Radiation_protection#Shielding

"If the entire mass of the atmosphere had a uniform density from sea level, it would terminate abruptly at an altitude of 8.50 km"
http://en.wikipedia.org/wiki/Atmosphere_of_Earth#Pressure_and_thickness

8500 [m] /150 [m] =56.(6)

Only 1 / 2 ^56.67 of this radiation would reach Earth surface.

The rest... heat?

 

[vemvare]

Is that really the half-value thickness of air to gamma rays of those frequencies?