If you examine this photo, you will see the blue tarp covering the crater.
https://www.fbi.gov/history/famous-cases/oklahoma-city-bombing
You are correct, thanks for pointing that out. I did more digging and found that the explosion left an 8’ crater. Nothing to the extent of the NK type but car bombs do leave a big dent. Most of the craters I have seen have been from projectiles or mines but IED’s that are not buried tend to not dig in.