Geology Chapter 2.13 (printed) 0.0 / 5 ? GeologyIgneous rocksA2/A-levelOCR Created by: abbbywCreated on: 05-12-17 19:36 Volcanic Explosivity Index (VEI) a measure of the explosiveness of volcanic eruption, allows comparison, from 0-8 of increasing explosivity 1 of 6 Hawiian eruptions large amounts of very fluid basaltic magma from which gases escape, few pyroclasts 2 of 6 Strombolian eruptions more explosive with less fluid basalt and andesite lava, regular explosions of gas + pyroclastic material 3 of 6 Vulcanian eruptions violent with viscous andesitic lava and large quantities of pyroclastic material from large explosions 4 of 6 Plinian eruptions extremely explosive with viscous gas-filled andesitic and ryholitic lava and tremendous volumes of pyroclastic material blasted out 5 of 6 Isopachyte a line jointing points of equal thickness of a deposit (ash). The maps may be called isopach maps 6 of 6
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