Irruption (noun)

1. A sudden, forceful entry or invasion.
2. A sudden, intense increase in the population of a species.

Origin:

From latin irruptio, from irrumpere 'to break in'.

Examples:

1. The irruption of the protesters into the city caused widespread chaos.
2. The irruption of a new bird species into the area caused concern for the native birds.
3. The irruption of technology in the workplace has changed the way people work.
4. The irruption of refugees into the country put a strain on the resources.
5. The irruption of magma from the volcano caused the lava flow.