September 23

September 23 - September 23 Products of volcanic...

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September 23 Products of volcanic activities: Lava flows: Basaltic lava flows- due to its low silica content and high temperatures, its quite fluid (viscosity- but stickier than maple syrup) temperate- 1100-1200 Celsius outrun lava flows? usually yes - flows slowly because it's sticky and viscous. not a problem generally for a person to run away from. couple of exceptions: in africa, in the republic of congo, volcano there that is right next to a city. it erupts basaltic lava. it turns out that the compoistion of the lava has a lot of sodium and potassium, which reduces the viscosity of the lava. so the alva flows quickly and very hard to outrun. this is a big hazard for the area and the residence of the city (goma) time it takes for lava to go from volcano to the town s short. pahoyhoy lava- smooth, ropy patterns, as it flows it's deforming. aa lava- very blocky on the surface and comparatively cool, if you cut into the lava and looked at a cross section, the outer surfaces have the blocky texture, below the surface the lava is fairly passive and much hotter. -- aa. . got the name is so hot. .. can't really walk on it. sometimes when lava flwos erupt, they can have some gas. baslatic lava can contains lots of gas fire fountains- large fountains of lava small explosive eruptions form fire fountains as partially liquid drops fall back to the ground, they may coalesce to form a lava flow (produced from this vent right here) - most basaltic eruptions don't form fire fountains. odoneo langae- unusual volcano magma- both normal silica magma and carbonotype (calcium carbonyte) magma - has a very low viscosity. - lava's black. looks like mud. instead of erupting at 1100 or 1200 c, it cmoes out at 500 or 600 c (melts at this temp) black lava becomes white, and at then looks red. plug basalts- type of super volcano eruptions consists of massive out pourrings, huge volumes of basaltic lava that have been erupted at various point of earths history and cover a very large region of the planet. flood basalt- columbian river flood river. cascade volcanic arch- formed by present day
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This note was uploaded on 09/24/2010 for the course ARTS NDIS235 taught by Professor Schwarts during the Fall '09 term at McGill.

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September 23 - September 23 Products of volcanic...

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