If it was an underground explosion, would its shape like this? And nobody tells anything about rocks and particles around.
I think, it was a meteorite. The soil is soft as syz reminded. A few meters beneath comes the water. It looks like a very old river(s) bed from the sattelites which collapses everywhere. The very big rocks cannot come there with ordinary rivers but by strong flood events in non-documented times. So, the earth surface is only a soft coverage of a mixture of mud and big rocks.
So the thing must be burried in the mud below. As it is in the mud in the soil, the heat must have been absorbed faster than expected -at least it does not reach at the surface anymore.
Or, truely, it looks like a work of a construction machine too. But I don't think there is a machine of that size there.
Also, the said size has been expanded upto 5 x 30 meters. It looks even larger. Or the cameramen should use normal lenses without any extras on these events. They don't inform about the soil structure, either.