First of all, we had to stitch the plates together with Photomerge to have a bigger image that will allow a vertical camera movement.
Once we had the image we had to remove the people to have a clean plate to start to work with for the meteor strike concept.
To start with the meteor strike concept I did a sketch showing the areas that will be affected and a rough concept just as a suggestion of composition and level of destruction.
I spent lots of hours searching for reference photos of disasters, craters, collapsed buildings, etc. that matched the result I was expecting.
I started erasing the building that I wanted to completely destroy and I marked the perspective of the building behind to reconstruct its hidden parts with the previously erased building that have a similar structure and color.
Then, I created a layer mixing together some of the research photographsto simulate the inside of the remaining building with the interior floors visible. After that I painted a mask that allowed me to show the areas that gave me the best result.
I used a bunch of photographs to do the crater and the collapsed zones.
For the partially destroyed buildings I chose carefully the images to match it suitably with the original plate according to the light, color, perspective and size, with special attention to the edges for areas that were too soft or too hard when combining images.
Once I placed the images to create the last crater I took the image of debris that you see below and I cleaned it of people, roads and red vehicles, having as a result a full image of debris. I modified the perspective to match it with the ground, I masked it to show only the areas I were interested in, and I applied some adjustment layers modifying specific parts of the image using a mask for each.
I worked with my debris ground as a Smart Object, allowing me to go back in the changes I did to the perspective and to the blur, applying the last only in the parts of the image I needed using the filter mask.
The last thing I did before starting with the final details and light/color general adjustments, was to recover some elements under the debris, like trees, stairs, phone cabins, etc. and applying them a saturation and color correction.
Finally, I spent the last hours correcting the direction of the lights and shadows, adjusting the black levels, adding some textures to the walls and roofs and giving a general texture and color to the image.