The term Mass Extinction (or Extinction Event) refers to a relatively short period in the history of Earth when many species went extinct. These are of astrophysical interest in investigating possible astrophysical causes such as Impacts or solar events. Also, when apparently caused by geological events, this can throw light into study of other bodies (Solar System planets and Moons and Extra-Solar Planets) and potentially Astrobiology.
There are twenty some very clear events, e.g., the one associated with the disappearance of dinosaurs, and in a few cases an Asteroid impact is suspected.
Details of how impacts caused extinction are a subject of study. In addition to the impact location itself, major Tsunami are possible, forest/vegetation fires possibly at great distances, and changes to the Atmosphere possibly lasting years.