Understanding the physical processes of frictional slip of subduction zone earthquakes from the characteristics of fault rocks.

从断层岩特征认识俯冲带地震摩擦滑移物理过程

• 批准号: 12440132
• 负责人: OTSUKI Kenshiro
• 金额: $ 9.79万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12440132/
• 关键词: 1999 Chu-Chu earthquake; Shelungpu fault; pseudotachylyte; elastohydrodynamic lubrication; comminution; fractal; fluidization; normal interface vibration; 海溝型地震; 集集地震; Chelungpu断層; 摩擦すべり実験; 海溝付加帯; 1999 Chu-Chu earthquake; Shelungpu fault; pseudotachylyte; elastohydrodynamic lubrication; comminution; fractal; fluidization; normal interface vibration; 海溝型地震; 集集地震; Chelungpu断層; 摩擦すべり実験; 海溝付加帯

Followings were known from the analysis of the core samples from the southern and northern boreholes penetrating the Shelungpu fault, the seismic fault of the 1999 Chi-Chi earthquake in Taiwan.1. At the depth of 176m of the southern borehole, we found the crushed pseudotachylyte layer about 2m thick. Recycled pseudotachylyte grains are common, indicating that seismic slips have repeated in this shear zone. Very small part of grains of crushed pseudotachylyte record high temperature (up to 1730℃) signatures, but major part of grains shows the texture of very low degree of melting.2. At the depth of 223-227m and 283-320m of the northern borehole, we found the several shear zones of the Shelungpu fault. The fault core of these shear zones is composed of soft clay layer of 1-3cm thickness, and it is commonly associated with a layer of about 1m thick fault breccia with mosaic texture. Clay veins from the fault core frequently intrude the fault breccia. This clay injection structure suggests … More the generation of instantaneous and abnormally high pore pressure.3. The southern and northern parts of the Shelungpu fault behaved very differently during the 1999 Chu-Chu earthquake; moderate slip associating the radiation of high frequency wave, while very large and smooth slip lacking the radiation of high frequency wave. These contrasting slip behaviors appear to be consistent with the fault rocks. Namely, the highly viscous melt of very low degree of melting in the south would have restrained the seismic slip, while the slip would have been promoted by the elastohydrodynamic lubrication (Brodsky and Kanamori, 2001) of fault clay layer.We studied the comminution and fluidization of fault gouges through analyzing fault gouges.1. Comminution starts at the fractal dimension 2.5 of grain size frequency, and the fractal dimension increases as further comminution. Fractal granular materials can be packed most densely when the fractal dimension is 2.5. Therefore, comminution itself is a slip-weakening mechanism.2. We developed a new method how to distinguish the gouges whether they have experienced fluidization or not.3. Normal interface vibration by Brune et al. (1993) is a most plausible cause of fluidization, and we presented two field evidences that support this mechanism.4. The knowledge of powder science teaches us that fault plane becomes nearly frictionless when gouge is fluidized. Less

从穿透Shelungpu断层的南部和北孔的核心样品的分析中得知了以下内容，这是1999年台湾Chi-Chi地震的地震断层。在南部钻孔的176m深度，我们发现碎的假鸟叶层厚约为2m。再生假甘油晶晶粒很常见，表明在该剪切区域重复地震滑动。碎型假谷藻的谷物中很小的一部分记录高温（长达1730年），但谷物的主要部分显示出非常低的熔化程度的质地。2。在北钻孔的223-227m和283-320m的深度，我们发现了Shelungpu断层的几个剪切区。这些剪切带的断层芯由1-3厘米厚的软粘土层组成，通常与大约1m厚的断层角砾岩和带有镶嵌的质地相关。断层核心的粘土静脉经常侵入断层角砾岩。这种粘土注入结构表明……更多的瞬时和绝对高孔隙压力的产生3。在1999年的Chu-chu地震期间，Shelungpu断层的南部和北部的行为差异很大。中等滑动与高频波的辐射相关，而非常大而平滑的滑动缺乏高频波的辐射。这些对比的滑动行为似乎与断层岩石一致。就是说，南部的高度粘性融化将限制地震滑动，而这种滑移将由粘土层的弹性水力动力学润滑（Brodsky和Kanamori，2001）促进。当分形尺寸为2.5时，粉碎尺寸的分形尺寸为2.5的2.5尺寸可以挤压。因此，粉碎本身就是一种湿滑的机制。2。我们开发了一种新方法，如何区分凿子是否经历了流动性。3。 Brune等人的正常界面振动。 （1993）是流化的最合理的原因，我们提供了两个支持该机制的领域证据。4。粉末科学的知识告诉我们，当凿子流化时，断层平面几乎无摩擦。较少的