I'm creating a world where one of its main characteristics is that it's being plagued by very frequent meteor impacts. These meteors, however, apart from the momentary terror and local catastrophe they cause, also usually carry a unique and incredibly valuable ore. The properties of this ore makes it so valuable that whole economies may be affected by a sudden influx.
Also, groups of people commonly referred to as Meteor Hunters (similarly to Tornado Hunters) devote their lives to predict (using astronomy) where the next meteor will fall, because if they manage to claim its ore they may become rich enough to feed their great-great-grandchildren. Others consider meteors a divine sign, etc.
You get the point, meteors are frequent and apart from their literal impact they also cause a social, religious, and financial impact.
Some important definitions before I ask my question:
- Ecosystem: The map my world takes place in with all its fauna and flora. The size of the map is approximately the size of North America (24.71 million km²).
- Irreversible Effect: An irreversible effect permanently changes the complexion of the ecosystem (e.g., the permanent rise of temperature, ecosystem collapse, etc.)
- Meteor Size: Assume that the largest possible meteor can have the size of the Chelyabinsk meteor. Larger meteors don't exist (or, simply, will never fall on my planet).
How many meteors can my ecosystem sustain without them causing an irreversible effect? Considering that the Chelyabinsk meteor did not threaten the ecosystem in any way (apart from local damages and injuries), is it safe to assume that my map can have frequent impacts of the same size (e.g., 1-3 per year) and dozens of smaller size ones without worrying about the ecosystem collapsing? Or is there some kind of an indirect effect that I'm not taking account of?