Rare events so catastrophic that they leave evidence in the geologic record and threaten life on Earth. Included are impacts by asteroids and comets, eruptions from giant resurgent volcanic calderas, large to mega-earthquakes and associated tsunami, and dramatic reduction of atmospheric oxygen by release of reservoirs of methane hydrate.
Rare events so catastrophic that they leave evidence in the geologic record and threaten life on Earth. Included are impacts by asteroids and comets, eruptions from giant resurgent volcanic calderas, large to mega-earthquakes and associated tsunami, and dramatic reduction of atmospheric oxygen by release of reservoirs of methane hydrate.
