Bubble-quantitative volcanology

气泡定量火山学

基本信息

批准号：
10440127
负责人：
TORAMARU Atsushi
金额：
$ 6.98万
依托单位：
kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The aim of this project has been to establish the methodology for the quantification of volcanic eruptions from the vesicular texture of pumices or scoriae. This aim has not bee achieved yet but we have get several important facts that will be valuable to the further development of this project as follows. (1) Attempt to estimate the strain rate in the conduit using tabular vesicles : In the case study of pumice flow deposit in Toya volcano, we found that the relationship between aspect ratio and size of vesicles plays an important role to estimate the strain rate in the volcanic conduit. (2) The textural analysis of scoria from the B crater Plinian eruption of 1986 Izu-oshima volcano : In this research, we found that the vesicularity and the number density of groundmass microlites negatively correlate and that in the early and final stages of the eruption the microlite-poor type (A type) is dominated whereas in the middle stage the microlite-rich type is dominated. If the elevation of the effective liquidus due to the degassing controls the microlite crystallization, this fact suggests that the magma ascent rate in conduit changes from a slow, through fast and to slow rates again during the eruption. (3) The experiment of bread baking using yeast fermentation : From the comparison of experimental results between the fermentation under free expansion and that in glass tubes, the 1 dimensional expansion enhances the bubble coalescence and elongation. This result has been taken into account in the first study concerning Toya volcano. These three studies confirm the underlying idea of this project that the vesicular texture can provide the important information for the quantification of volcanic eruption.

该项目的目的是建立从泡泡糖或斯科里亚的水泡质地定量火山喷发的方法。这个目标尚未实现，但是我们有几个重要事实，对于该项目的进一步发展，如下所示。（1）尝试使用表格囊泡估算导管中的应变速率：在Toya火山中浮石流量沉积的案例研究中，我们发现纵横比与囊泡大小之间的关系对于估计火山导管中的应变速率起着重要作用。（2）1986年Izu-oshima火山的B火山口plinian爆发的Scoria质地分析：在这项研究中，我们发现，囊泡性和地下摩斯微矿的数量密度是负相关的，并且在喷发的早期和最终阶段，在喷发的早期和最终阶段，类型（一个类型）占主导地位，当时是统一的。如果由于脱气而导致的有效液体的升高控制微橙石的结晶，则此事实表明导管中的岩浆上升速率从缓慢，快速到速度在喷发过程中再次降低速率。（3）使用酵母发酵的面包烘烤实验：根据自由膨胀下的发酵和玻璃管中的发酵结果的比较，1尺寸膨胀增强了气泡的结合和伸长率。该结果已在有关Toya火山的第一项研究中考虑到了。这三项研究证实了该项目的基本思想，即囊泡质地可以为量化火山喷发提供重要信息。