OOC. Its Tunguska, its around 10 or 20 megatons. Enough to vape a city,
nowhere near whats needed to "destroy American heartland". I really want people to start having a clue about what they talk about when it comes to big and small asteroids or SF space ship firepower.
Its just like when some newspaper or "science" show goes telling something is
ten thousand times the firepower of Hiroshima bomb. They present it as world ending threat.

10,000 Little Boys. Or around 150 megatons and some 3 times stronger than largest nuke ever tested, and I think I would have noticed if world has been destroyed.
Same with meteors. To current data, things that result in kiloton level blast are smallest that will produce any actuall result, and even then blast is almost always high in atmosphere with little effect on the ground. Tunguska object was likely 10 to couple dozen meters in diameter and produced blast in 10-15 megaton range. (Though around 20km high in the air). Dino killer was couple kilometers in diameter and AFAIK produced a blast in range of 50 teratons. 50 thousand gigatons or 50 million megatons. Now thats big and dangerouns.