Final answer:
Asteroid impacts similar in size to the Tunguska airburst are rare, occurring once every few hundred to one thousand years. While the chance of such an asteroid destroying an urban area is statistically low, the potential for massive devastation exists if one were to impact a populated area.
Step-by-step explanation:
The event you are referring to is called the Tunguska event, an explosion that occurred in 1908 over Siberia and is estimated to be the result of an asteroid about 40 meters in diameter. This asteroid disintegrated in the atmosphere with the force of approximately a 5-megaton nuclear explosion. The frequency of such events impacting an urban area is difficult to predict exactly, as it relies on numerous variables, but it is statistically rare.
The Tunguska-sized impacts occur roughly once every few hundred to one thousand years. If the Tunguska projectile had exploded over a densely populated urban area like New York City instead of a remote area in Siberia, it could have resulted in one of the deadliest events in human history. Earth resides in a cosmic shooting gallery, and while major events are infrequent, they are not impossible. Monitoring and planetary defense are key in protecting our planet from such events.