CompuServe Thread

Scott: I am not an authority on Vocanos, and I eagerly await someone who is coming up with answers to some of your interesting questions. But I can interject some irrelevent factoids and questions anyway <g>… >> 1) What is the larges volcano in the last 10,000 years or so-where,when and how does it compare to Tambora 1815?>> Wasn't Tambora a calvera? If so, isn't it different than a regular volcano? << 2) What is the largest volcano known for all time and how does it compare in order of magnitude to Tambora 1815?>> I don't know, but in recent years, i.e., the last several million, one good candidate must be the eruption that created the Tulu Bor tuff in East Africa. Covered the entire red sea and much of east africa with a very thick layer of ash. Nobody has figgured out where the volcano was! Cheers, GTL Greg Laden Dept. of Anthropology Harvard University Cambridge MA 02138

Scott, Volcanology was an interest of mine a few years ago, but unfortunately, right now I don't have any good references on it. I do know that one of the largest eruptions of recent geologic times was the series of blasts that destroyed Mount Mazama in Oregon. It's estimated that the Mazama eruption produced 50-70 cubic kilometers of ejecta. How much did the 1815 Tamboro eruption produce? There was another titanic eruption, largely of light ash, several million years ago, again in the Cascades. We know about that one mainly because of a unique fossil find in Idaho or Montana, a large number of mammals that were apparently killed by volcanic ash when they were gathered around a water hole. There was a big article about that in National Geographic sometime in the early 80s, maybe 1981 or '82. Other biggies: Krakatoa produced a lot of noise, but I don't know how much ejecta. There was a volcanic island in the eastern Mediterranean (Thera, now called Santorin) that exploded about 1500 BC with such force that it atomized the island, almost destroyed Minoan Crete, wrought havoc all over the Med., Asia Minor, and northern Africa, and quite possibly was the inspiration for the legend of Atlantis. All that's left of Thera today is a caldera with an area of about eighty square kilometers. Jon W.

Hi, Scott– Welcome to the forum/section! The October 1993 Scientific American had an article on large igneous provinces, results of episodes where awesome amounts of basalt erupted over a relatively short time, such as the Deccan traps of India (that eruption is a candidate for the dinosaur-killer, last I heard). There is no mention of individual volcanoes, but it seems there must have been volcanoes in those place/times that would have made anything we know of look quite wimpy. –Doug

Hi Scott, I'm not a volcanologist either and some of this info goes beyond your 10,000-year area of interest but here goes: Mt St Helens, 1-2 cubic km Katmai, Alaska 1912, 7 cu km Krakatoa, 18 cu km Mazama, 75 cu km Tamboro, 150 cu km Yellowstone National Park : Mesa Falls Tuff (1.2 million yrs) 280 cu km; Lava Creek tuff (600,000 yrs) 1000 cu km; Huckleberry Ridge Tuff (2.2 million yrs) 2500 cu km. Info is from the Indiana University Geology Field Camp guidebook, citing Smith & Braile (1982)– Crustal structure and evolution of an explosive silicic volcanic system at Yellowstons, 1982 Wyoming Geological Association Guidebook. Hope this is useful. Cheers, Dick Gibson