In the film Broken Arrow, a nuclear weapon is set off underground in an abandoned mine.
Here is the scene:
I'm interested in two points in this clip:
First at 0:33, you can see the ground sink as it falls into the mine shaft. (I'm not worried about the explosion - that looks like a typical petrol & explosives set up. It's the ground falling in that interests me.)
Then at 0:55, you can see the ground rippling and moving as it comes up behind and under the Jeep.
The first one looks quite realistic - as if they really did set off explosives underground.
The second also looks realistic, but could be a miniature or CGI.
Is there any information on how those effects were achieved? Did they actually set off a big underground explosion, or was it miniatures and standard small blasts?