Comprehensive high-precision relocation of global seismicity

区域和全球地震网络每年探测和记录数十万次地震。地震台网运营商定期分析他们的地震图，以估计各种参数，包括每个新地震的时间，位置和震级，增加了快速增长的数字地震数据档案。地震位置目录是地震学和一般地球科学的基本数据来源。然而，这些地点的空间分辨率非常低，这限制了它们解决有关地球结构和组成的基本问题的潜力。的内部，地震的性质，以及它们对我们的社会和建筑环境造成的地震危害。该项目的主要目标是利用地震档案数量和质量不断增加以及可负担得起的计算能力，采用高阶地震定位方法，大幅提高全球数百万次地震的定位精度。该项目将侧重于利用丰富的高精度数据，以比较的方式更好地了解控制全世界俯冲带的孕震结构和过程。该项目的成果有望在地球科学领域得到广泛应用，并在自然灾害和《全面禁止核试验条约》（CTBT）的地震核查领域产生社会影响。过去几十年来，全球地震档案的巨大增长，计算成本的持续下降，地震重定位方法的进步为大大提高标准全球地震目录的空间分辨率提供了独特的机会。这些目录中的震源位置，通常是根据全球地震台站观测到的相位到达时间一次估计一个事件，其准确性非常低，这阻碍了广泛研究领域的研究，不仅在地震学中，而且在一般的地球科学中。这个持续的项目建立在以前的工作，开发高效率的波形互相关和双差（DD）算法重新定位超过300万地震在国际地震中心（ISC）和NEIC的联合公报？地震数据报告，跨越1964-2012年。这些工具通过利用新的程序来科普这种大规模工作的计算负荷，从而提高了地震位置的精度。基于互相关的相位延迟时间是在数十亿对波形上测量的，高效的双差算法结合报告的相位到达时间来反演这些数据。使用这种方法的初步结果已经揭示了地震活动在时间和空间上的特征，并提供了新的数据，有助于以前所未有的分辨率深入了解地震孕育过程。 该项目将重点关注俯冲带Wadati-Benioff区地震活动的精细结构和狭窄双地震带的性质，并分析与最近大俯冲地震相关的重新定位的地震活动，以更好地了解其结构和运动学行为。全球DD目录可能会在地球科学中找到许多应用，并可能有助于提高我们对控制地震的物理过程的理解，以及我们对地球结构和组成的成像能力。的内部，我们的能力，以估计大地震造成的危害。

Hundreds of thousands of earthquakes are detected and recorded each year by regional and global seismic networks. Seismic network operators routinely analyze their seismograms to estimate various parameters, including time, location, and magnitude of each new earthquake, adding to a rapidly growing archive of digital seismic data. Catalogs of earthquake locations are a fundamental source of data in seismology, and in the Earth sciences in general. Yet these individual locations have had notoriously low spatial resolution, which limits their potential to address fundamental questions concerning the structure and composition of the Earth?s interior, the nature of earthquakes, and the seismic hazards they impose on our society and the built environment. The main goal of this project is to significantly improve the location precision of millions of earthquakes on a global scale by applying higher-order earthquake location methods that take advantage of the increasing quantity and quality of seismic archives and the availability of affordable computing power. This project will focus on using the wealth of high-precision data to better understand, in a comparative way, the seismogenic structure and processes that control subduction zones worldwide. Results from this project are expected to find many applications in the Earth Sciences, and to have social impact in the areas of natural hazards and seismic verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT).The tremendous growth in global seismic archives over the last several decades, the continuous fall in computing costs, and advances in earthquake relocation methods provide a unique opportunity to substantially improve the spatial resolution of standard global earthquake catalogs. The locations of hypocenters in these catalogs, typically estimated one event at a time from phase arrival times observed at global seismic stations, have notoriously low accuracy that hamper studies in a wide range of research areas, not only in Seismology, but in the Geosciences in general. This continuing project builds on previous work that developed high-efficiency waveform cross-correlation and double-difference (DD) algorithms to relocate more than 3 million earthquakes listed in the combined bulletins of the International Seismological Centre (ISC) and NEIC?s Earthquake Data Report, spanning the years 1964-2012. These tools increase the precision of the earthquake locations by harnessing new procedures that can cope with the computational load of this massive-scale undertaking. Cross-correlation based phase delay times are measured on billions of pairs of waveforms, and efficient teleseismic double-difference algorithms invert these data in combination with reported phase arrival times. Initial results using this approach already reveal characteristic seismicity patterns in time and space, and provide new data that help gain insight into seismogenic processes at unprecedented resolution. This project will focus on the fine-scale structure of Wadati-Benioff zone seismicity at subduction zones and the nature of narrow double-seismic zones, and analyze the relocated seismicity associated with recent great subduction earthquakes to better understand their structural and kinematic behavior. A global DD catalog will likely find many applications in the Earth Sciences, and may help improve our understanding of the physical processes controlling earthquakes, our ability to image the structure and composition of the Earth?s interior, and our capability to estimate the hazards imposed by large earthquakes.