Dynamic Nankai Trough (Japan) & Middle America Trench (Costa Rica) Sediment Triaxial Experiments

对日本和哥斯达黎加近海地震多发俯冲带的沉积动力学和构造演化进行了大量工作。这项工作表明，超孔隙压力是密切相关的脱水和流体流动过程中的增生和下冲断层沉积物。然而，迄今为止，对瞬时孔隙压力变化和矿物学控制对沉积物破坏的影响的研究仅限于静态变形。因此，不能考虑诸如循环荷载或地震震动等动态效应。另一方面，越来越多的证据表明，特别是循环加载，否则稳定的系统可能会触发（液压）故障。在这个低成本的建议，我们建议进行实验室测试，使用最先进的实验室技术，以模拟地震震颤的原始全轮（WR）样本恢复在OOP腿170和190。实验策略是双重的：（i）我们提交了一个等分试样的每个样品类似的围压和循环载荷，以研究孔隙压力的演变和故障的差异，（ii）然后，我们采取地震记录，从最近的地震在每个地区，并提交了其他等分试样的相同样品，这些应力下的预固结应力（即推断在原位条件）。这不仅可以让我们了解机械响应，还可以对灾难性故障进行一些风险评估。这项研究是使用一个定制的，一个的一类动态（高达50赫兹），计算机控制的三轴剪切仪最近开发的海洋岩土工程实验室在RCOM不莱梅。

A large body of work has been carried out on the sedimentary dynamics and tectonic evolution of the earthquake-prone subduction zones off Japan and Costa Rica. This work suggests that excess pore pressures are closely linked to dehydration and fluid flow processes in the accreted and underthrust sediments. However, the study of the effects of transient pore pressure changes and mineralogical controls on sediment failure have so far been restricted to static deformation. As a consequence, dynamic effects such as cyclic loading or earthquake shaking could not be considered. On the other hand, increasing evidence suggests that especially cyclic loading of otherwise stable systems may trigger (hydraulic) failure. In this low-cost proposal, we propose to carry out laboratory tests using a1state-of-the-art laboratory technology to simulate earthquake tremor on pristine whole round (WR) samples recovered during OOP legs 170 and 190. The experimental strategy is two-fold: (i) We submit an aliquot of each sample similar confining stresses and cyclic loads to study differences in pore pressure evolution and failure, (ii) We then take seismic records from recent earthquakes in each area and submit the other aliquot of the same sample to these stresses under their pre-consolidation stresses (i.e. inferred in situ conditions). This will not only allow us to learn about the mechanical response, but some risk assessment concerning catastrophic failure. The study is carried out using a custom-built, one-of-a-kind dynamic (up to 50 Hz), computer-controlled triaxial shear apparatus recently developed at the Marine Geotechnics laboratory at RCOM Bremen.