Determination of streaming potential coefficients in various physical and chemical conditions to quantitatively estimate interstitial fluid's flow from tempral and spatial self-potential variations on Miyakejima island

我们确定zeta电位在各种物理和化学条件下的室内实验，定量评估间隙液的流动从时间和空间的自电位变化与宫岛2000年峰会喷发。第一年，我们设计并准备了必要的仪器，并在三宅岛和小津岛收集了岩石样品。由于我们发现小津岛的地形效应约为10 mV/m（海拔每变化1 m，地形效应降低10 mV），是三宅岛（1 mV/m）的10倍，因此测量和比较两岛岩石样品的zeta电位成为本研究的另一个目标。三宅岛（Mikyakejima）和小津岛（Kozushima）分别由玄武岩和流纹岩组成，主要结果如下：（1）用HCl-KCl-KOH组成的间隙流体测定了三宅岛岩石zeta电位的p依赖性。pH 3-10范围内的Zeta电位值为-10至-20 mV，其绝对值比Ishido & Mizutani（1981）的结果小10倍，该结果被视为代表性Zeta电位值。在较高的pH条件下，zeta电位的绝对值变大，变得与他们的结果相似。（2）在pH>3的范围内，两岛岩石的Zeta电位对pH的依赖性基本相同。在较低的pH范围内，三宅岛岩的Zeta电位绝对值变小，在pH 2左右变为零，在进一步的酸性条件下变为正值，而小津岛岩的Zeta电位绝对值变化不明显，仍为负值。（3）对于较细的岩石样品，得到的Zeta电位绝对值较大。

We determined zeta-potential in various physical and chemical conditions by room experiment to quantitatively evaluate interstitial fluid's flow from temporal and spatial self-potential variations in association with Miyakejima 2000 summit eruption. In the first year, we designed and prepared necessary apparatus and collected rock samples on Miyakejima and Kozushima islands. Since we found that the topographic effect on Kozushima island is about 10mV/m (10mV decrease pre 1m altitude change), which is 10 times larger than that on Miyakejima island (1mV/m), measurement and comparison of zeta-potentials for the rock samples in both islands become another target of this study. Mikyakejima and Kozushima islands are composed of basalts and rhyolites, respectively.Main results are as follows:(1)p dependence of zeta-potential for Miyakejima rocks was determined by using interstitial fluids of HCl-KCl-KOH composition. Zeta-potential values in pH 3-10 range from -10 to -20 mV, whose absolute value is 10 times smaller than Ishido & Mizutani (1981)'s results, which were regarded as representative zeta-potential values. In the higher pH conditions, zeta-potential absolute value gets larger and becomes similar to their results.(2)For both islands' rocks, pH dependence of zeta-potential in pH>3 range is almost the same. In the smaller pH range, zeta-potential absolute value of Miyakejima rocks is getting smaler, becomes zero at about pH 2 and changed to be positive in further acid condition, whereas that of Kozushima rocks shows no such significant variation and remains negative.(3)For results with the finer rock samples, the larger zeta-potential absolute value is obtained.