Global Seismic Imaging of the Oceanic Plates

地球的外层由坚硬的构造板块组成，就像一个破裂的蛋壳。这些板块在行星表面下方较弱、较热的一层上滑动。从刚性板块到下面的地幔的过渡是板块构造和我们在地球上存在的基础。然而，板块的定义，即它们的厚度、定义机制以及与下面的层的耦合程度还不是很清楚，我将利用全球地震成像来了解地球海洋板块的厚度和定义机制。海洋板块覆盖了地球表面的70%，但由于地处偏远，在4公里深的海洋底部部署地震仪的难度和成本较高，很少有人以高分辨率绘制地图。我已经开发了一种新的方法，在站点覆盖稀少的位置绘制板块图，就像在海洋下面一样。我使用的是SS波，这是一种在地球表面反弹了一次的S波。SS波特征的细微变化提供了关于弹跳点区域构造板块底部深度和特征的信息。我将使用一个新编制的全球数据库(1990-2011)，其大小接近4TB，约为我以前调查中数据的四倍。其重要意义在于，我将对所有大洋盆地拥有近乎完美的分辨率，使全球能够进行比较，并对构造板块有一个统一的看法。板块的定义对影响人类生存的许多过程都有影响。它从根本上控制着板块的运动方式。这包括地震、火山和海啸的产生。因此，更好地了解将有助于更好地评估和减轻自然灾害。此外，板块厚度和强度直接影响构造板块的隆升和下沉。这些力量影响着造山和海平面上升，因此是理解气候变化的重要因素。这项研究的结果将改变教科书，并澄清基本问题。我将更好地理解构造板块的定义，包括它的形成和演化。了解海洋板块对任何构造环境都是至关重要的，因为它们可能在大陆的形成中扮演着重要的角色。总体而言，这项工作将加深我们对板块构造的理解。

The outer layer of the earth is composed of rigid tectonic plates, like a cracked eggshell. These plates slide around the surface of the planet over a weaker, hotter layer below. The transition from rigid plate to the mantle below is fundamental to plate tectonics and our existence on the planet. However, the definition of the plate, i.e., their thickness, defining mechanism, and degree of coupling to the layer below are not well-known.I will use global seismic imaging to understand the thickness and defining mechanism of the Earth's oceanic plates. The ocean plates cover 70% of Earth's surface, yet are rarely mapped at high resolution given the remoteness, and the difficulty and cost of deploying seismometers to the bottom of a 4 km deep ocean. I have developed a new methodology to map the plates in locations where station coverage is sparse, as it is beneath the oceans. I use the SS waveform, which is an S wave that has bounced once at Earth's surface. Subtle variations in the character of the SS wave give information on the depth and character of the base of the tectonic plate in the region of the bouncepoint.I will use a newly compiled global database (1990 - 2011) which is nearly 4TB in size, and represents about four-times the data in my previous investigations. The significance is that I will be have nearly perfect resolution across all ocean basins, enabling global comparisons and a unified view of the tectonic plate.The definition of the plate has implications for many processes that impact human existence. It has a fundamental control on how plates move. This includes the generation of earthquakes, volcanoes, and tsunamis. Therefore a better understanding will lead to better hazard assessment and mitigation of natural disasters. In addition, plate thickness and strength directly affects uplift and subsidence of the tectonic plate. These forces impact mountain building and sea level rise, and are therefore important factors in understanding climate change. The results from this study will change text books, and clarify fundamental questions. I will develop a better understanding of the definition of a tectonic plate, including its formation and evolution. Understanding the ocean plates is fundamental to any tectonic setting in that they likely play a large role in the formation of the continents. Overall, this work will deepen our understanding of plate tectonics.