I expect 500 kt would have been more than sufficient to wipe out Chelyabinsk, if the explosion had not occurred so high up (altitude estimated at 16 to 19 miles). I wonder what the SIOP had allocated to it, back in the day.
Before the shock wave arrived, the Russians had time to observe the flash, which lasted some seconds, building to a peak, and go outside with their cameras and pan back and forth at the sky, chattering excitedly. Then crack! Windows shattered, doors blown in, car alarms set off, dogs barking. Some 1100 people sought medical attention.
Actually, reports said the problem is that people ran to their windows to see what had happened. Then 3 minutes later about 4,000 buildings had their windows blown in. Three minutes at 5 seconds per mile = 36 miles away.
I have read elsewhere that people in London were able to read their newspapers at night from the light of Tungusku. I also read that a boloid strike in the Amazon, I think in the 1930s, flattened an area about 50 miles in diameter.