This discussion concerns the flowage of the 1991 lava lobes at Unzen that were suggested by Goto et al. (2020) to be moving rigidly. Pictorial evidence of flowage of the 1991 lava lobe of Unzen, such as morphological change of the lava lobe, protrusion of the front of lava lobe, crease structure, and wrinkle surface of lava blocks, are presented. Differences in the interpretation of flow mechanisms may reflect slight difference in temperature and glass composition of the lavas. Temperatures used by Goto et al. (2020) were 780–880 °C, whereas those estimated by Venezky and Rutherford (1999) were 900 ± 30 °C. The groundmass glass compositions of 1991 blocks of Unzen dacite used by Goto et al. (2020) are 1–2 wt% higher in SiO₂ than those of Nakada and Motomura (1999) and ours, suggesting that the samples used by Goto et al. (2020) represent the cooler rigid parts of the lava lobes. The lava viscosity is delicately influenced by cooling, dewatering, and crystallization during eruption. The direct application of experimental results to understanding the rheological behavior of natural lavas needs much more careful consideration.

该讨论涉及 Goto 等人建议的 1991 年云仙熔岩裂片的流动。(2020) 刚性移动。展示了1991年云仙熔岩叶流动的图像证据，如熔岩叶的形态变化、熔岩叶前部的突出、褶皱结构和熔岩块的皱纹表面。流动机制解释的差异可能反映了熔岩温度和玻璃成分的细微差异。Goto 等人使用的温度。(2020) 为 780–880 °C，而 Venezky 和 ​​Rutherford (1999) 估计的温度为 900 ± 30 °C。Goto 等人使用的 1991 块云仙英安岩的地块玻璃成分。(2020) 在 SiO _{2 中}高出 1–2 wt%比 Nakada 和 Motomura（1999）和我们的，表明 Goto 等人使用的样本。(2020) 代表熔岩叶中较冷的刚性部分。熔岩粘度受到喷发期间冷却、脱水和结晶的微妙影响。将实验结果直接应用于理解天然熔岩的流变行为需要更加仔细的考虑。