Iceland, the Siberian Traps, Deccan Traps, and the Ontong Java Plateau, are extensive regions of basalts on a continental scale resulting from flood basalt eruptions. When created, these regions often occupy several thousand square kilometres and have volumes on the order of millions of cubic kilometers. In most cases, the lavas are normally laid down over several million years. They release large amounts of gases. The Réunion hotspot produced the Deccan Traps about 66 million years ago, coincident with the Cretaceous–Paleogene extinction event. The scientific consensus is that a meteor impact was the cause of the extinction event, but the volcanic activity may have caused environmental stresses on extant species up to the Cretaceous–Paleogene boundary. Additionally, the largest flood basalt event (the Siberian Traps) occurred around 250 million years ago and was coincident with the largest mass extinction in history, the Permian–Triassic extinction event, although it is unknown whether it was solely responsible for the extinction event. Such outpourings are not explosive, though lava fountains may occur. Many volcanologists consider Iceland to be a large igneous province that is currently being formed. The last major outpouring occurred in 1783–84 from the Laki fissure, which is approximately long. An estimated of basaltic lava was poured out during the eruption (VEI 4). The Ontong Java Plateau has an area of about , and the province was at least 50% larger before the Manihiki and Hikurangi Plateaus broke away. Massive explosive eruptions Volcanic eruptions are classified using the Volcanic explosivity index, or VEI. It is a logarithmic scale, which means that an increase of one in VEI number is equivalent to a tenfold increase in volume of erupted material. VEI 7 or VEI 8 eruptions are so powerful that they often form circular calderas rather than cones because the downward withdrawal of magma causes the overlying rock mass to collapse into the empty magma chamber beneath it. Known super eruptions Based on incomplete statistics, at least 60 VEI 8 eruptions have been identified. Below is a list of well-known super-eruptions. Media portrayal Nova featured an episode "Mystery of the Megavolcano" in September 2006 examining such eruptions in the last 100,000 years. Supervolcano is the title of a British-Canadian television disaster film, first released in 2005. It tells a fictional story of a supereruption at Yellowstone. Gallery See also Notes References Further reading External links Overview and Transcript of the original BBC program Yellowstone