The process of converting the lava flow into volcanic ash.

本文从9个方面形象的分析了熔岩流到火山灰的特点。“在岩浆成分中，有三个因素影响火山的形成，即水、二氧化碳和石英。水和二氧化碳的比例越高，岩石的熔融温度越低。火成岩浆的二氧化硅含量的比值越高，岩浆的粘度越高；反之亦然。”

1. The higher the ratio of silica content in the igneous magmas is, the higher the viscosity of the magmas is; vice versa.

2. Among the magma components, there are three factors that impact the formation of volcano, which are water, carbon dioxide and silica. The higher the proportion of water and CO2 is, the lower the temperature of melting of the rocks is. The more the silica is, the faster the magmas flows.

3. a) Volcanic landslides; pyroclastic flows; lateral blasts; ash; gases; phreatic and hydrothermal explosions.
b) Volcanic landslides; pyroclastic flows; lateral blasts; lava dome; lava flows; lahars; floods; ash; gases, phreatic and hydrothermal explosion.
c) Pyroclastic flows; lateral blasts; ash.
d) Volcanic landslides; pyroclastic flows; lahars; floods; ash; gases.

4. The lava flows may impose a great hazard to the properties, but not much for people. Lava flows mostly move at a speed slower than human could walk. The very high temperature of the lava would burn the property; if not, when the lava’s temperature comes down, it would solidify around the property.

5. In the Old Faithful area, there are mostly plateau rhyolite. Rhyolite has a very high proportion of silica, which may make the melting temperature of the rocks much lower than other kinds of rocks. Besides, the hot water existing in this area would reduce the melting temperature even more. There is a high possibility of phreatic and hydrothermal explosions in this area and so does the small-scale lava flows. 

6. At the Mammoth area, there is a mixture of Lava Creek Tuff and Pre Caldera rocks. The most common rocks here are the dacite and rhyolite. There are many fumaroles in this area. The volcanic gas discharge is very prevailing here, causing mazuku. 

7. Judging from the maps, the area of Huckleberry Ridge ash Bed is larger. Though the Huckleberry Ridge ash bed is smaller in the north and southeast part, the area on the Pacific Ocean is much larger.

8. Different. In the map of Lava Creek B ash bed, the ash bed expands more in south-north direction; and the ash bed is more round in shape. There is an eminent extension at the southeast area, which demonstrates that the wind had blew more in the southeast direction. And in the map of Huckleberry Ridge ash bed, the shape of the ash bed is oval, and the eminent extension is at the west area, which demonstrates that the wind had blew in east direction.

9. A) The pressures in the volcano when the eruption happened were different. The intensity and direction of winds during and after the erupting times were different, which would influence the area and the shape of the ash bed. The precipitation after the volcanic eruption would impact the ash bed as well.
B) Because the principles of volcano forming are the same in applying in analysis of all volcanoes, such as the composition of the rocks at that area, geologic conditions and climate. The conditions may vary, but the way these conditions impact the volcanic eruption is unvaried. 

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