Collaborative Research: Catching the quake: Investigating samples from the JFAST expedition for evidence of the 2011 Tohoku Earthquake

这一建议试图通过确定断裂开始前和滑动过程中断层的摩擦强度来了解东北地震期间浅层滑动是如何发生的。利用IODP EXP 341期间从断层上收集的样本，皮？S将进行：1)有机热成熟度测量，以确定破裂面并量化同震滑动引起的摩擦温度异常；2)微观结构观察，以识别和表征承载地震的断层，包括识别摩擦减弱的结构；3)摩擦测量，以约束断层的稳态摩擦应力。这些结果对于理解浅俯冲区海啸的成因至关重要，并将为海啸预测和减灾提供关键信息。重要的是，只有对故障物理性质的直接观察和测量才能确定这些参数。东北地震令人惊讶，此前的研究表明，该地区不太可能发生这样的地震，特别是在？弱？地区发生大范围滑动的地区。浅层吸积棱柱沉积。了解这次地震需要了解断裂带岩石的摩擦特性。有三种可能的情况：第一，断层在快速滑动过程中可能经历了戏剧性的摩擦减弱，导致了极低的同震应力。或者，地震前的应力很低，断层上的变化很小，断层上的变化很小，滑动是由断层更深的部分传递的应力驱动的。最后，滑动可能已经通过断层的速度增强区传播，而断层平均几乎没有减弱。更广泛的影响：关于如何在浅层沉积物中托管一次重大(和意外的)海啸地震的信息。更好地了解引发海啸的地震具有重大的社会意义。

This proposal seeks to understand how shallow slip occurred during the Tohoku earthquake by determining the frictional strength of the fault before the rupture initiated and during slip. Using samples collected from the fault during IODP exp 341 (JFast), the PI?s will undertake:1) Organic thermal maturity measurements to identify the rupture plane and quantify the frictional temperature anomaly induced by coseismic slip.2) Microstructure observations to identify and characterize the fault that hosted the earthquake, including the identification of textures that indicate frictional weakening.3) Friction measurements to constrain the steady-state frictional stress of the faults.These results are crucial for understanding tsunami genesis in shallow subduction zones and will provide critical information for tsunami prediction and hazard mitigation. Importantly, only direct observation and measurement of the fault physical properties can determine these parameters. The Tohoku quake was a surprise, previous work had indicated that such a quake was unlikely in region, especially one in which large amounts of slip occurred in ?weak? shallow accretionary prism sediment. Understanding this quake requires understanding frictional characteristics of rocks in fault zone. There are three plausible scenarios:First, the fault could have undergone dramatic frictional weakening during rapid slip resulting in very low stress coseismically. Alternatively, stress prior to the earthquake was low and changes on the fault were small coseismically, with slip driven by stress transferred from the deeper part of the fault Finally, slip could have propagated through a velocity-strengthening region of the fault with little fault weakening on average.Broader impacts: Information relating to how a major (and unexpected) tsunami-generating quake was hosted in shallow sediments. A better understanding of tsunamigenic earthquakes has great societal importance.