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There is ample evidence of a global firestorm at the time of the Chicxulub impact. Iridium-bearing clay in the boundary layer between the Cretaceous Period (a time when dinosaurs roamed) and Tertiary Period (the subsequent geologic time frame when dinosaurs seem to have disappeared) contains soot.
The quantity and composition of the soot corresponds to the burning of at least 50 percent of the world's forests. Although Hurdle's idea that methane fires were responsible for this firestorm is plausible, there is another simpler explanation.
The Chicxulub impact would have launched millions of tons of rock into ballistic space flight. Over the following hour this debris would have re-entered the Earth's atmosphere at high speed, causing millions of brilliant "shooting stars." The radiant heat from these meteors alone would have been sufficient to ignite the trees around the world.
This idea is supported by the discovery of charcoal in tsunami deposits near the impact site. The best explanation may be that the trees were ignited by radiant heat, then swamped soon after by the waves.
The shock wave from the impact would indeed have triggered massive earthquakes in the region and indirectly triggered other earthquakes around the globe. A tsunami would have formed from the impact, which occurred in a shallow sea. The giant waves would also have been generated by the earthquakes and undersea landslides triggered by the shock wave.
"Megawaves emanating from an impact site would circuit the earth at high speeds and cause worldwide disruption in the entire ocean in a single day," Hurdle and his colleagues wrote.
So dinosaurs, if they were not consumed in a firestorm, would have had to live through a torturous sequence of events -- from the barbecue to the freezer, to a dip in acid and then a hothouse baking.
How an Asteroid Impact Causes Extinction
The debate continues on whether the Chicxulub impact caused the mass extinction at the end of the Cretaceous Period or whether it was one of a sequence of disasters. The Deccan Traps of India are the remnants of a massive upwelling of molten rock from deep within the Earth 65 million years ago. The toxic fumes and dust from the eruption have been put forward as a possible alternative cause of climate change that led to the extinction of the dinosaurs.
A possible link between impacts and volcanism became evident in 1974 when the Mariner 10 spacecraft flew past the innermost planet Mercury. The planet was found to be covered with impact craters like the moon. One giant impact crater on Mercury was particularly interesting. Directly opposite the impact point, on the other side of the planet (called the "antipodal point") was a region of highly disrupted terrain with no evidence of an impact. The shock waves from the impact on one side of Mercury had traveled around the surface and met simultaneously at the antipodal point to create the chaotic features. Similar features have since been detected on several moons of the giant planets.
Astronomer Duncan Steel has suggested that the same occurred with the Chicxulub impact and that the shock waves caused the Deccan Traps. Taking into account millions of years of continental drift, this region would have been at the antipodal point to Mexico at the time of the impact. Although the eruption may have contributed to the suffering, it now seems more likely that the Deccan Traps were just a consequence of the catastrophic initial event, the Chicxulub impact.
There is substantial evidence to show that within the time of the supervolcano Toba's eruption in the Indonesian Pacific, the world's population of homo sapiens decreased from over one hundred thousand to less than two thousand, basically because global temperatures dropped five degrees for many years. This was within the current interglacial and at its start.
The Mount Toba eruption is dated to approximately 71,000 years ago. Volcanic ash from Mount Toba can be traced north-west across India, where a widespread terrestrial marker bed exists of primary and reworked airfall ash, in beds that are commonly 1 to 3, and occasionally 6 meters [18 feet] thick.
Tambora, the largest known historic eruption, displaced 20 cubic kilometres of ash. Mount Toba produced 800 cubic kilometres.* It was therefore forty times larger than the largest eruption of the last two centuries and apparently the second largest known explosive eruption over the last 450 million years.
*Mount St Helens produced a tiny 0.2 cubic kilometres.
Volcanic Winter, and Differentiation of Modern Humans
Mount Toba's eruption is marked by a 6 year period during which the largest amount of volcanic sulphur was deposited in the past 110,000 years. This dramatic event was followed by 1000 years of the lowest ice core oxygen isotope ratios of the last glacial period. In other words, for 1000 years immediately following the eruption, the earth witnessed temperatures colder than during the Last Glacial Maximum at 18-21,000 years ago.
For the volcanic aerosols to be effectively distributed around the earth, the plume from the volcanic eruptions must reach the stratosphere, a height greater than 17 kilometres. Mount Toba's plume probably reached twice this height. Most solar energy falls at low latitudes between the Tropics of Cancer and Capricorn, so eruptions that happen near the Equator cause much more substantial cooling due to the reflection of solar energy. Toba lies 2 degrees north of the Equator, on the Island Sumatra.
The reduction in atmospheric visibility due to volcanic ash and dust particles is relatively short-lived, about three to six months. Longer-term global climatic cooling is caused by the highly reflective sulphuric acid haze, which stays suspended in the upper atmosphere for several years.
Ice core evidence implicates Mount Toba as the cause of coldest millennium of the late Pleistocene. It shows that this eruption injected more sulphur that remained in the atmosphere fo a longer time [six years] than any other volcanic eruption in the last 110,000 years. This may have caused nearly complete deforestation of southeast Asia, and at the same time to have lowered sea surface temperatures by 3 to 3.5 degrees centigrade for several years.
If Tambora caused the " The year without a summer" in 1816, Mount Toba could have been responsible for six years of relentless volcanic winter, thus causing a massive deforestation, a disastrous famine for all living creatures, and a near extinction of Humankind.
The Yellowstone Plateau volcanic field developed through three volcanic cycles spanning two million years that included some of the world's largest known eruptions. Eruption of the >2450 cu km Huckleberry Ridge Tuff about 2 million years ago created the more than 75-km-long Island Park caldera. The second cycle concluded with the eruption of the Mesa Falls Tuff around 1.3 million years ago, forming the 16-km-wide Henrys Fork caldera at the western end of the first caldera. Activity subsequently shifted to the present Yellowstone Plateau and culminated 640,000 years ago with the eruption of the >1000 cu km Lava Creek Tuff and the formation of the present 45 x 85 km caldera. Resurgent doming subsequently occurred at both the NE and SW sides of the caldera and voluminous (1000 cu km) intracaldera rhyolitic lava flows were erupted between 150,000 and 70,000 years ago.
Volcanic activity began in the area about 3.6 million years ago when trachybasalt and trachyandesite lava flows covered an area of about 1,500 square miles (4,000 square km). A short time later, geologically speaking, rhyodacite was erupted as flows and domes. Geologists interpreted these more silica-rich compositions as the first eruptive products of a growing magma chamber.
The Long Valley caldera was produced by a catastrophic eruption about 730,000 years ago. The roof above the magma chamber collapsed, forcing 150 cubic miles (600 cubic km) of rhyolitic magma to the surface in the form of Plinian ash columns and associated air falls and ash flows. The volume of ash is comparable to similar caldera-forming eruptions at Yellowstone and far exceeds the volume of ash erupted from stratovolcanoes. For example, the large eruption of Tambora in 1815 produced 10 cubic miles (40 cubic km) of ash.
The cataclysmic eruption of Mount Mazama 7,700 years ago started from a single vent on the northeast side of the volcano as a towering column of pumice and ash that reached some 30 miles (50 km) high. Winds carried the ash across much of the Pacific Northwest and parts of southern Canada.
The 181AD Taupo eruption
This eruption took place from a vent or vents near the Horomatangi Reefs, now submerged on the eastern side of Lake Taupo. The eruption lasted between several days and several weeks and produced a sequence of pumice deposits that blanketed the landscape east of Taupo. In total about 100km3 was erupted.
At the climax of this eruption, about 30km3 of pumice, ash and rock fragments was erupted in only a few minutes and travelled horizontally as a liquid flow, moving at speeds estimated at between 600-900kmh. It crossed every obstacle in its path except the top of Mt Ruapehu.
it produced an eruption column 50km high -- twice as high as the 1980 Mt St Helens eruption column.
it was the most violent eruption in the world in the past 5000 years.
Taupo volcano represents a major scientific challenge in that its activity is so variable. In the last 50,000 years, it has had eruptions that vary in volume from 0.05km3 (slightly larger than a typical Ruapehu eruption) to over 800km3.
After a long period of inactivity (about 200 years), Krakatoa became active again in early 1883. The first indication that something was happening on Krakatoa was when a large earthquake struck the area. Seismic activity became stronger until May 20,1883, when the volcano abruptly came to life. The initial explosive eruptions of Krakatoa could be heard 160 km away. Steam and ash could be seen rising 11km above the summit of the volcano. By August 11, 1883. three vents were actively erupting. Eleven other vents were ejecting smaller quantities of steam, ash and dust.
Around 1 pm on the 26th of August 1883, the explosions became more frequent occurring on the average every 10 minutes. Sailors on a ship, 120 km away from the island reported a black cloud of smoke rising above the volcano. At the time the rim of Krakatoa's crater was approximately 1,000 meters in diameter and had and average depth of 50 meters. The volcano' s central vent was blocked by a plug of solid lava and underneath it pressure was rapidly building up.
The Great Eruption
The renewed activity in May 1883 culminated in four gigantic explosions on August 26 and 27 of the same year. On the afternoon of August 26, 1883, (27 August local date) at 17: 07 Greenwich time (GMT), the first of these four violent explosions begun. A black cloud of ash was initially observed. It rose 17 miles (27 kilometers) above Krakatoa. In the morning of the next day, on August 27, 1883, at 05:30, 06:44 and 10:02 GMT, three more violent eruptions occurred. It was the paroxysmal eruption which occurred at 10:02 which blew away the northern two-thirds of the island. This was the most severe violent volcanic explosion on Earth in modern times. The explosion was followed by the collapse of the unsupported volcanic chambers of Krakatoa forming the huge underwater caldera. It was this explosion and collapse of Krakatoa that generated catastrophic tsunami waves as high as 37 meters. (120 ft.) that caused havoc and destruction in the Sunda Strait.
The 1883 eruption of Krakatoa has been assigned a Volcanic Explosivity Index or VEI of 6 which rates as "colossal". To be assigned a VEI rating of 6, a volcanic eruption must have a plume height over 25 km and a displacement volume ranging between 10 and 100 km3 (cubic kilometers). Eruptions of this size occur only once every few hundred years on earth.
The total energy released by the four main events of the 1883 eruption was equivalent to 200 megatons of TNT. Most of this energy was released by the third paroxysmal explosion which has been estimated to be equivalent to an explosion of 150 megatons of TNT. To understand the magnitude of the Krakatoa explosion, it will suffice to say that the Hiroshima atomic bomb was only about 20 kilotons).
This frightening display of volcanic power would culminate in a series of at least four stupendous eruptions that began at 5:30 a.m., climaxing in a colossal blast that literally blew Krakatau apart. The noise was heard over 4600 km away, throughout the Indian Ocean, from Rodriguez Island and Sri Lanka in the west, to Australia in the east.
One compeling feature of the Krakatau eruption is that the pyroclastic flows appear to have travelled an incredible 40 km across the Sunda Straits, where they remained hot enough to cause the burn-related fatalities on Sumatra. These same flows, however, were also recorded by several ships located at greater distances. On August 27, the Louden (see above) was located ~65 km north-northeast of Krakatau when it was struck by severe winds and tephra, and the W.H. Besse was located at ~80 km east-northeast of Krakatau when it was hit by hurricane-force winds, heavy tephra, and the strong smell of sulfur. At these greater distances, the pyroclastic flows were at lower temperatures so that the ships and crew survived.
Originally posted by Tusayen
Personally I votes for super Volcanoes LOL you get to at least enjoy a spectacle before the world collapses