Comprehensive high-precision relocation of global seismicity

区域和全球地震网络每年检测和记录数十万次地震。网络运营商定期分析地震图以估计各种参数，包括每次新地震的时间、位置和震级。 这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内部结构和组成、地震性质以及地震对我们社会和建筑环境造成的危害等基本问题的潜力。该项目的主要目标是通过应用高阶地震定位方法，利用不断增加的地震档案数量和质量以及可承受的计算能力，显着提高全球范围内数百万次地震的定位精度。该项目将侧重于利用大量新数据，以比较的方式更好地了解控制全球俯冲带的发震结构和过程。该项目的成果预计将在地球科学中得到广泛应用，并在自然灾害和《全面禁止核试验条约》的地震验证领域产生社会影响。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以​​及地震重定位方法的进步，为大幅提高标准全球地震目录的空间分辨率提供了独特的机会。该项目将利用高效的远震波形互相关和双差（DD）算法，对1964年至2011年国际地震中心和NEIC地震数据报告联合公报中列出的超过300万次地震进行全面重新定位。这些目录中震源的位置通常根据全球地震台观测到的相位到达时间一次估计一个事件，其精度众所周知，这阻碍了广泛研究领域的研究，不仅在地震学领域，而且在整个地球科学领域。该项目旨在通过使用新程序同时重新定位震源来显着提高目录的空间分辨率，这些新程序可以通过利用计算机集群来应对这一大规模任务的计算负载。将在数十亿对波形上测量基于互相关的相位延迟时间，并将采用高效的远震双差算法结合报告的连接震源矢量的相位到达时间来反演这些数据。新的全球DD目录有可能揭示时间和空间上的特征性地震活动模式，并以前所未有的分辨率提供对地震发生过程的新见解。 该项目将重点关注瓦达蒂-贝尼奥夫带地震活动的精细尺度结构和狭窄双地震带的性质，并分析与近期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，提高我们对地球内部结构和组成进行成像的能力，以及我们估计大地震造成的危害的能力。

Hundreds of thousands of earthquakes are detected and recorded each year by regional and global seismic networks. Network operators routinely analyze their seismograms to estimate various parameters, including time, location, and magnitude of each new earthquake. This adds 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 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 new 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 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. This project will use high-efficiency teleseismic waveform cross-correlation and double-difference (DD) algorithms to comprehensively relocate the more than 3 million earthquakes listed in the combined bulletins of the International Seismological Centre and NEIC?s Earthquake Data Report, spanning the years 1964-2011. 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 project aims at significantly increasing spatial resolution of the catalogs by relocating the hypocenters simultaneously by using new procedures that can cope with the computational load of this massive-scale undertaking through harnessing computer clusters. Cross-correlation based phase delay times will be measured on billions of pairs of waveforms, and efficient teleseismic double-difference algorithms will be employed to invert these data in combination with reported phase arrival times for the vector connecting their hypocenters. The new global DD catalog has the potential to reveal characteristic seismicity patterns in time and space, and to provide new insights into seismogenic processes at unprecedented resolution. This project will focus on the fine-scale structure of Wadati-Benioff zone seismicity 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 in improving 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.