one of the most dangerous hot spot below plate rises

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Unformatted text preview: ge amounts of pyroclastic debris and gases are released through ring fractures surrounding the summit. - one of the most dangerous - hot spot below plate, rises up through continental - stiff The crater produced by such collapse is called a caldera. - contain lots of gases - volcano colapses 18 6 Types of Volcanoes: Calderas - when volcano erupts then caves in The largest volcano to have affected humans was Toba, which erupted last in approximately 73,500 B.C.E. - 74 000 BC - almost killed off man kind Only remaining evidence of Toba is an enormous caldera100 km in ______ diameter. Based on current estimates, a huge volume of volcanic ash, equivalent to 2,800 km2 of solid rock was injected up to 30 km into the atmosphere. 19 Types of Volcanoes: Calderas, cont’d - fine grains went into atmosphere (blocks out solar radiation) Computer models of atmosphere response to the Toba eruption suggest that the ash and aerosols were of sufficient volume to drive tropical freezing temperatures to the ______ point for days to weeks and to produce abnormally cool temperatures for as long as a decade. - temps may have been so extreme, may have been freezing point - at this time, pop wasn't high (mostly in Africa) - ppl living day to day (hunting&gathering) aka food dies off Such temperatures would have been detrimental to any humans, and it has been speculated that humans may have come dangerously close to _________ ! extinction - barely made it out alive 20 - sheild: mafic, high temp, little gas, gentle eruption (rock type: Basalt/ • have solid, have gasses (trying to escape) dark, aphanitic) - composite: magma is intermediet to felsic (higher silica), stiffer, lava Volcano Types = shorter, more viscus, gasses = pulverize it, explosive at times , mafic • starts to cool, plugs up, pressure builds (debre, lava, debre, lava) - dome: stiff magma, forms plug, highly viscus, gass builds up that it explodes • codera 7 Volcanic Hazards: Types Primary Volcanic Hazards: • Lava flows • Pyroclastic activity (flows, ash falls) • Lateral blasts • Release of gases Secondary Volcanic Hazards • De...
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