[D20 Modern] Campaign Trigger Event Idea

[Buddha the DM]

What kind of impact, from an exterrestrial source, do people think it would take to completely destroy every within 20 miles of Ground Zero? Any and all ideas will be entertained.

Just for a point of reference this event will take place in San Francisco, California. Ground Zero is Alcatraz Island.

 

[ragboy]

What kind of impact, from an exterrestrial source, do people think it would take to completely destroy every within 20 miles of Ground Zero? Any and all ideas will be entertained.

Just for a point of reference this event will take place in San Francisco, California. Ground Zero is Alcatraz Island.

Here's what I found on a quick search:

The 1908 Tunguska Event in Siberia occurred when an asteroid or comet estimated at 200 feet wide and weighing about 100,000 tons exploded five miles above the Earth, releasing approximately 20-40 megatons of energy and leaving tiny grains of cosmic matter embedded in the trees knocked down by the blast. An area the size of Rhode Island was devastated in the explosion, killing wildlife within 20 miles of the impact, and creating fires that burned for weeks. Falls in the class of the Tunguska and Barringer variety occur over land only about once every millennium.

From here: http://www.hq.nasa.gov/office/pao/History/impact.html

 

[Buddha the DM]

Thanks for the information and the site link, but I am already aware of the Tunguska Event in Siberia. I was hoping to use something other than a comet or asteroid as the impact medium. Any ideas on that?

 

[wedgeski]

Thanks for the information and the site link, but I am already aware of the Tunguska Event in Siberia. I was hoping to use something other than a comet or asteroid as the impact medium. Any ideas on that?

You want it from an extraterrestrial source and not to be a comet or asteroid? Hmm. How about a downed spacecraft or space station? A load of space debris that gets magically attracted to your impact point? (Hey, cool super-villain weapon.)

I also quite enjoyed (as in: laughed at) that bit in The Core when the killer x-rays from space pierced the atmosphere over San Francisco and melted the Golden Gate, but that doesn't really qualify as an 'impact'.

Hope that stimulates!

 

[Retro-Rocket]

How about someone summoning Azathoth!

 

[DMScott]

What kind of impact, from an exterrestrial source, do people think it would take to completely destroy every within 20 miles of Ground Zero? Any and all ideas will be entertained.

It kinda depends on how completely you want everything destroyed, and what sort of destruction you want outside that radius. An impact that would basically vaporise everything within 20 miles is going to have much wider secondary effects than one that "only" destroys all the structures, leaving rubble and ruins.

Assuming the Tunguska-type devastation is what you're looking at but you don't want an asteroid or comet, then what you need is something with similar characteristics - either an explosive of 20 megatons or more, or another 100 kton object from space. Nothing humans have put into orbit is anywhere close to big enough - the International Space Station is currently 187 tons, only a little over 1% of what you need, and is planned to be about 420 tons at completion - so objects from space are going to have to be either natural or from a completely unknown source to qualify.

If you want to stay relatively realistic but not use an asteroid or comet, an airburst nuclear explosion is probably your best bet.

 

[Peterson]

Well, if you're looking for something more deliberate than a random astroid, you could always use an exterrestrial weapon of some sort. If you want to keep some mystery to that fact that it was a deliberate "attack", I suggest using what WEG's D6 Star Wars system called Mass Drive Cannons (which basically hurled large asteroids at very high speeds - which could devastate a planet without planetary shields; planets like Earth).

However, if you don't want a weapon, I second the idea of having an extremely large spacecraft crash. Maybe a spacecraft from Earth's future?

Peterson

 

[Buddha the DM]

Nice ideas all.

 

[Chaldfont]

I'm no astrophysicist, but couldn't an object of lower mass but with higher kinetic energy achieve the same thing? Say a spacecraft moving at near relativistic speeds? It might slow down somewhat in the atmosphere but still have enough energy to do some serious damage and spread fallout far from the impact point.

Something moving that fast on a collision course with earth (either accidentally or purposefully) might be hard to detect in time to warn anyone, let alone evacuate such a densely populated area.

If the spacecraft had super-high technology protection, some or all of it might even survive the impact. A fun session would be to play the team sent in to investigate.

Oh wait, did I just rip off the first Robotech book? I think I did.

 

[Chaldfont]

Ooooh, I just had an idea: A teeny-tiny chunk of antimatter protected by a magnetic field until reaching the target.

One millionth of a gram of positrons contain as much energy as 37.8 kilograms (83 pounds) of TNT, according to Edwards' March speech. A simple calculation, then, shows that about 50-millionths of a gram could generate a blast equal to the explosion (roughly 4,000 pounds of TNT, according to the FBI) at the Alfred P. Murrah Federal Building in Oklahoma City in 1995.

see: http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2004/10/04/MNGM393GPK1.DTL