< p >在流变学方面,有一个关键区别水和岩浆:水是牛顿流体,熔岩不是。在早期火山学,一直试图模型熔岩牛顿流体(< a href = " https://doi.org/10.1086/624778 " rel = " nofollow noreferrer " >尼科尔斯,1939 < / >)。这种方法在某些情况下可能是一个好的近似(液体熔岩,像pāhoehoe流),但不适合更多的粘性熔岩('ā和块流,看到< a href = " https://doi.org/10.1007/s00445 - 016 - 1075 - 7”rel = " nofollow noreferrer " >哈里斯et al。(2017) < / >回顾这些类别)。< / p > < p > < a href = " https://doi.org/10.1111/j.1365 - 246 x.1974.tb05460.x”rel = " nofollow noreferrer " >休姆(1974)< / >是第一个模型熔岩< a href = " https://en.wikipedia.org/wiki/Bingham_plastic " rel = " nofollow noreferrer " >宾汉塑性< / >。在宾厄姆流变学,剪切速率仍然尺度线性剪切应力(如在牛顿流变学),但是你需要达到最少的压力(“收益率stress")在流程开始之前。这流变学解释了一些关键差异流动形态而言,如上所述,休姆:< / p > < blockquote > < p >如果熔岩理想牛顿液体会流下坡和将继续流即使发泄的供应已经停止,直到面对经济萧条。此外横向流蔓延直到受地形限制或者直到表面张力阻止传播的时间是极薄。观测表明,岩浆并不会这样做。通常它就停在斜坡的供应新鲜的熔岩停止和许多流方面虽然无侧限高陡地形特征。很明显,有一些过程限制了熔岩的流动,让它停在斜坡上,防止横向扩散。< / p > < /引用> < p >近年来,进展模型熔岩多相流体:熔岩的确是一个悬挂的泡沫和/或在硅酸盐熔体晶体,这些粒子在熔岩流变学中发挥作用。 Finally, there is the case of silica-rich flows (dacite and rhyolite flows), which have very high viscosities ($10^8-10^{12}$ Pa s, compared to $10^3-10^6$ Pa s for basalts). These flows are so viscous that they advance very slowly (typically 1-100 meters per day). Hence their flow dynamics are very different from that of water. Unless you consider solid water: there are some similarities between these lava flows and the flow of glaciers, like the presence of ogives for instance (Thorarinsson, 1953).
References
Nichols (1939) Viscosity of Lava
Thorarinsson (1953) Ogives in Lava Streams
Hulme (1974) The Interpretation of Lava Flow Morphology
Harris et al. (2017) Pāhoehoe, ‘a‘ā, and block lava: an illustrated history of the nomenclature