Frictional properties of megathrust gouges

To better understand and more reliably model subduction zone seismogenesis, we determined the frictional properties of previously obtained natural megathrust fault gouges from exhumed subduction zone sediments exposed on Shikoku Island, Japan. These gouges correspond to peak paleo-temperatures of 105°C to 470°C, representing different stages in the diagenetic and metamorphic evolution of the subducted sediments and covering the aseismic zones as well as the seismogenic zone. We determined the frictional characteristics of these materials at the sample-specific, approximate peak in-situ PT conditions, i.e. the PT conditions corresponding to the maximum burial depth of these samples, applying pore fluid overpressure ratios of 0.65 or 0.90. The experiments were performed using the ring shear machine at Utrecht University.

为更深入解析俯冲带地震成因并构建更可靠的俯冲带地震成因模型，我们针对日本四国岛出露的抬升型俯冲带沉积物中采集的天然巨型逆冲断层泥，开展了摩擦特性测试。这些断层泥的古温度峰值介于105℃至470℃之间，对应俯冲沉积物成岩与变质演化的不同阶段，覆盖了无震带与发震带区间。我们针对每个样品的近似原位峰值温压（Pressure-Temperature）条件——即匹配各样品最大埋藏深度的温压条件——对该类物质的摩擦特性进行了表征，测试过程中采用的孔隙流体超压比为0.65或0.90。本实验于乌得勒支大学使用环剪试验机完成。