St. Petersburg Event instead of Tunguska Event

30 June 1908: The asteroid fragment that OTL exploded above Siberia in the Tunguska Event instead, due to its travelling slightly faster than OTL, explodes directly above St. Petersburg with a force equivalent to 15 Megatons of TNT, completely destroying the city, wrecking the Russian Baltic Fleet, instantly killing the Tsar and his entire family, and decapitating the Russian government and military command structure.

What happens next?
 
If it was travelling faster it would'nt have hit the Earth in the first place, you can have an even similar to Tunguska at different times, but you can't have the Tunguska asteroid hit anywhere else on Earth except where it did.
 
If it was travelling faster it would'nt have hit the Earth in the first place, you can have an even similar to Tunguska at different times, but you can't have the Tunguska asteroid hit anywhere else on Earth except where it did.

An earlier thread about a "Sarajevo Event" said that it could be made to hit at about the same latitude, but a different longitude, by making it go VERY VERY SLIGHTLY faster or slower.

Hence my thoughts on a "St. Petersburg Event".
 
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