February 2015 Challenge : Troubles at Rochefort

[Francissimo]

Hello cartographers, i've already worked once on a post apocalyptic map and it was a lot of fun so i'll try to do something this month.
My workflow so far:
1 download openstreet map data in QGIS for the city of Rochefort and start to play with them in photoshop and illustrator to add some effects and textures.
2 use raster analysis on the aerial view of rochefort to gain data about land use (concrete, crops..) and texture them in photoshop, also use the brush to add some vegetation
### Latest WIP ###
rochef-01-01.jpg

[Ilanthar]

Nice map already. I would just underline more the coastal line.

[Francissimo]

Thanks for the feedback Ilanthar, i'll try to work coastlines with waves if i have the time , lot of work this month so i only have a short time for the contest.
Second step of the map, a meteor hit the city, oh damn
### Latest WIP ###
rochef-01-03.jpg

[ChickPea]

Haha, I love this! That's one big crater.

[Chick]

Nice idea, but check out what a fresh meteor crater actually looks like, there needs to be a central peak

[jshoer]

Not necessarily - it depends how big the meteor is. The smallest make "simple craters" which are flat-bottomed bowls, as Francissimo drew. Medium-sized impacts make craters with central peaks, which get classified as "complex craters." The biggest impactors make complex craters with concentric ring systems.

Assuming those are buildings fit for humans or human-sized creatures, a simple bowl crater looks about right to me. Compare to the real Meteor Crater in Arizona, for instance, which conveniently has nearby buildings for scale.

Nice work on that crater, Francissimo - but I would make sure all those buildings look like they got flattened. A blast like that isn't going to leave much standing in the vicinity!

[Chick]

You're right, up to about 2-3 mi diameter on Earth, you may not get a central peak formed.

[Larb]

This crater talk is pretty enlightening. Do any of you have links to all the different types of crater? My main world has a gulf of mexico type of impact site in the ocean so I am curious.

Also that impact crater - would the immediate presence of the ocean possibly cause it to fill up with water? What sort of depth crater would it be and would there be any seepage of sea water into it?

It's looking really nice, by the way.

[jshoer]

This link looks like it hits the points in some of the research papers I have lying around from planetary science courses... Make sure to click around.

As far as I'm aware, the impact itself is almost an instantaneous process. I know one way geologists model impact cratering is as if a bomb blew up at some shallow depth under the ground - it blows everything out and away. So, in the initial heating and blast, a lot of the nearby water would be vaporized. The crater would develop its outer ridge as the ejecta starts to fall back toward the ground. But the ejecta does fall on top of existing topography, so if the crater hit a slope next to the ocean, maybe the shoreward rim would be shallow enough that the sea would fill the crater in. Regardless of the immediate result, the crater rim is going to be subject to erosion just like anything else, and the ocean could certainly get in there at some later time.

The Moon has a lot of cool complex crater structures with terraced rings. Try doing a Google image search for "complex crater" or "terraced crater!"

[waldronate]

Ejecta is a key word and one that's pretty much missing from this map. The type of crater shown here is much more reminiscent of an underground nuclear explosion that almost breaches the surface ( https://www.google.com/maps/@37.1757.../data=!3m1!1e3 ).