Making craters with shells

[Shadowwave]

I am making a mini movie and i would like to know how i could make it so that when a bomb shell hits the beach it creates a crater under it in the sand. Im not sure how i could do it, but here is an example of what kind of shell i would like:

http://www.nintendospin.com/images/1207/ss01.jpg

If anyone also had any tutorials on how to make nicer effects like explosions that would be cool too!

Thanks!

[DjVoyager]

You will need to use Dynamics, using particles and softbodies. Now it's one of those things where you have to see the reaction of your animating objects at the time of collision to know what values would work best.
I highly recommend getting the Soft and Rigid Bodies kit that shows a snow ball falling from a top of a roof on to the soft snow.
http://www.digitaltutors.com/store/product.php?productid=62&cat=42&page=1

Check out the first part of the tutorial;
http://www.digitaltutors.com/digital_tutors/display_video_store.php?vid=534
Hope that helps.