Broadband Seismological Investigations of Earth Structure and Earthquake Sources

在这项为期四年的更新提案中，PI利用宽带数字地震数据巩固了他的研究工作，以解决有关地震破裂过程和深部地球结构的基本问题。主要的重点是对地震波记录进行定量分析，以确定大地震是如何破裂的，破裂产生的地面震动是如何受到断层作用的影响，海底断层作用是如何产生海啸的，以及一次地震的应力变化如何影响其他地震。这一努力直接关系到全球减轻地震和海啸损害以及发展对自然地震和海啸事件的复原力。该项目的更广泛影响包括研究生培训、公众宣传和促进世界各地俯冲带沿线的地震危险评估。拟议的研究将建立在以下领域取得的重大进展的基础上：(1)宽带地震体和表面波、海啸观测和利用其对震源过程的互补敏感性的高速率大地测量数据的联合建模和反演将持续进行，并应用于最近发生在墨西哥和Komandorsky群岛的大地震；(2)开发新的地震学程序，用于评估俯冲带板块边界地震的上倾破裂程度，利用水的多重激励的三维数值模拟来约束近沟破裂；(3)综合不同类型断层的大地震地震参数将在已完成的大型逆冲事件基础上进行扩展，包括进一步探索辐射能量增强因子（REEF），这是一种新的大地震相对地震能量释放指标，其特征是破裂复杂性的差异；(4)利用下地幔相相平衡的约束条件，通过分离源、接收和深部对波形的贡献，对深地震的多尺度地震图阵列进行叠加和建模，以增强最底地幔端部区域的P和S速度结构图像。这项全面的研究工作将涉及PI和两名研究生，他们将从事震源和结构研究问题，并与其他机构的同事继续合作。我们期望在描述与地震过程和地球内部动力结构相关的重要动力过程方面取得持续进展，这是该项目的主要智力价值。更广泛的影响将是对研究生的培训，对发展中国家地震/海啸灾害评估的贡献，提高公众对地震过程和地球动力学的认识，研究生与面向stem的本科新生的互动，以及对地球物理大挑战问题的多学科研究的贡献。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this four-year renewal proposal the PI consolidates his research efforts using broadband digital seismic data to address fundamental questions about earthquake rupture processes and deep earth structure. The primary focus is on quantitative analysis of seismic wave recordings to determine how large earthquakes rupture, how ground shaking from the ruptures is affected by the faulting process, how tsunami are generated by submarine faulting, and how stress changes from one earthquake affect other earthquakes. This effort is directly relevant to the global mitigation of earthquake and tsunami damage and development of resilience to natural earthquake and tsunami events. Broader impacts of this project include training of graduate students, public outreach and contributing to seismic hazard assessment along subduction zones around the world.The proposed research will build upon the significant progress made under the expiring four-year grant in the following areas: (1) joint modeling and inversion of broadband seismic body and surface waves, tsunami observations, and high-rate geodetic data that exploits their complementary sensitivity to source processes will be sustained, with application to recent great earthquakes in Mexico and the Komandorsky Islands; (2) development of new seismological procedures for evaluating the up-dip extent of rupture in subduction zone plate boundary earthquakes will be undertaken, with 3D numerical modeling of water multiple excitation to constrain near-trench-rupture; (3) synthesis of large earthquake seismological parameters for different categories of faulting will be extended from completed work on megathrust events, including further exploration of the Radiated Energy Enhancement Factor (REEF), which is a new measure of relative seismic energy release for large earthquakes that characterizes differences in rupture complexity; and (4) stacking and modeling of multi-scale arrays of seismograms from deep earthquakes will be performed to enhance images of P and S velocity structure in end-member regions of the lowermost mantle applying constraints from phase equilibria for lower mantle phases, with procedures for separating source, receiver and deep contributions to the waveforms. This overall research effort will involve the PI and two graduate students who will engage in both earthquake source and structure research problems, along with continuing collaborations with colleagues at other institutions. We anticipate sustaining progress in characterizing important dynamical processes associated with earthquake processes and the Earth's internal dynamical structures as the primary intellectual merit of the project. The broader impacts will be on graduate student training, contribution to seismic/tsunami hazard assessment in developing nations, enhancing public awareness of earthquake processes and earth dynamics, graduate student interaction with STEM-oriented undergraduate freshmen, and contribution to multidisciplinary research on geophysical grand challenge problems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.