The Chicxulub impact event was an extraordinarily energetic event in Earth history. It is also coincident with one of the largest mass extinction events in Earth's history, which occurred 65 million years ago. Are these two events connected? That is,  could an impact event have caused the deaths of so many plants and animals, and, if so, how?

    At the moment, we do not know the complete answer to this question. To cause extinctions, an impact event must induce long-term changes in the physical or biological environment over such a large area than an organism could not escape by migrating or adapting.  We know that some of the environmental changes produced by the impact affected only particular regions of the world, while other changes were global. Which of these changes or combinations of changes caused the extinction of specific species is still unclear and that question is the focus of many current studies.  Nonetheless, we can describe some of the environmental effects that occurred, even if we do not know how they affected specific organisms.

    In the vicinity of the impact, the blast and heat destroyed life.  Forests were flattened to a distance of 500 to 1000 km. Because part of the crater was in a shallow sea, giant tsunamis radiated across the Gulf of Mexico.  Geologic evidence of these waves crashing onto the coastline exist in Mexico and the United States.  If the impact had occurred in a deep ocean basin, these waves might have been 4 to 5 km high and affected coastlines as far away as 10,000 km.  Because the Chicxulub impact occurred in relatively shallow water, approximately 100 m deep, the waves were probably not nearly as large.
 

    One estimate suggests waves that hit the Texas coast were "only" 50 to 100 m high.  Additional waves developed when millions of tons of ejected debris came crashing back down into the Gulf of Mexico and Caribbean seas.  The powerful earthquakes that jolted the region immediately after the impact caused landslides along the coastline, generating more tsunamis.