Characterization of Subduction Zone Earthquake Rupture Parameters with Respect to Subduction Zone Complexity

OCE-0751610智力优势：俯冲带，即一个构造板块俯冲到另一个构造板块之下的位置，产生了世界上大多数的地震，其中一些也产生了毁灭性的海啸。俯冲带地震的地震特征，包括破裂的时间常数，范围从典型的快速（几秒-10秒）破裂到缓慢，持续时间长（100秒）的海啸事件，到无声（几天-几年）地震。地震参数变化的原因目前还不清楚，但影响破裂的原因可能是非常重要的地震和海啸灾害评估。俯冲带条件的几个方面对影响地震破裂可能很重要。本项目的重点是俯冲板块输入对地震破裂特征的影响。虽然全球表征将是理想的，但数据的实际限制需要关注具有良好表征的输入和大型地震目录的区域。目前的工作应集中在中美洲和北方日本俯冲带，因为每个都有测深确定的沿走向输入变化，以及在过去的缓慢，无声，或海啸地震。这里要检验的主要假设是，俯冲板块的复杂性将决定不同震级范围内地震破裂特征的变化，具体假设将在每个地区进行检验。预计在中美洲，1）在海隆占主导地位的地区，地震持续时间短和/或应力下降较大，因为海山的作用增加了耦合。相反，2）在地垒和地堑为主的地区，由于俯冲沉积物的存在，削弱了耦合和较低的破裂速度，因此持续时间长/应力降较低的地震较为普遍。对于北方日本，预计也有类似的模式，3）在平滑区域发现持续时间较短和应力降较高的地震，4）在有大量俯冲沉积物的地垒和地堑区域发现持续时间较长/应力降较低的地震。此外，5）如果俯冲带构造复杂性是影响破裂过程的关键因素，那么日本和中美洲地垒和地堑区的地震参数将是相似的。如果观测结果证明了这些，则可以得出结论，俯冲板块的复杂性并不是影响地震破裂复杂性的唯一因素，这将导致未来对其他参数的研究，例如覆盖板块控制、沉积物成分、流体来源和温度。这两个俯冲带都是NSF边缘癫痫发作的焦点地点，因此这项工作将引起科学界的极大兴趣。该项目将支持和培训一名研究生在新墨西哥州技术，少数民族服务机构。此外，首席研究员将与新墨西哥州技术联盟的少数民族参与（AMP）计划，招募少数民族本科研究助理。该计划有助于将教师与对研究经验感兴趣的学生相匹配，并指导他们进入研究生院。

OCE-0751610Intellectual Merit: Subduction zones, i.e. locations where one tectonic plate dives beneath another, produce the majority of the world's earthquakes, some of which also produce devastating tsunami. Seismic characteristics of subduction zone earthquakes, including the time constant of rupture, range from typical fast (few-10s seconds) ruptures to slow, long duration (100s of seconds) tsunami events, to silent (days-years) earthquakes. Causes for variations in the seismic parameters are currently not well understood, yet the causative factors influencing rupture could be very important in seismic and tsunami hazard assessment. Several aspects of subduction zone conditions may be important for influencing earthquake rupture. This project focuses on the effects of subducting plate inputs on earthquake rupture characteristics. Although global characterization would be ideal, practical limitations of data require focusing on zones with well characterized inputs and large seismic catalogs. The present work shall focus on the Central America and northern Japan subduction zones, as each have bathymetrically-determined along-strike input variations, as well as having slow, silent, or tsunami earthquakes in the past. The overarching hypothesis that will be examined here is that complexity on the subducting plate will dictate variations in rupture characteristics for earthquakes over a range of magnitudes.Specific hypotheses will be tested in each region. It is expected that in Central America 1) earthquakes in a seamount-dominated region will have short durations and/or higher stress drops because seamounts act to increase the coupling. In contrast, 2) earthquakes with long durations/lower stress drop are prevalent in the horst and graben dominated regions because the availability of subducted sediment acts to weaken couplingand lower rupture velocities. For northern Japan, a similar pattern is anticipated, with 3) earthquakes with shorter durations and higher stress drops found in the smooth regions and 4) longer duration/lower stress drops in the horst and graben region with ample subducting sediment. In addition, 5) earthquake parameters for the horst and graben regions of both Japan and Central America will be similar if the subduction zonestructural complexity is the key factor influencing the rupture process. If observations prove these otherwise, it will be concluded that subducting plate complexity alone is not the sole influence on earthquake rupture complexity, leading to future investigations of other parameters, such as overriding plate controls, sediment composition, fluid sources, and temperature.Broader Impacts: Because of the focus on earthquakes and tsunami, this work has direct societal benefits. Both subduction zones are NSF-MARGINS SEIZE focus sites, thus this work would be of great interest to that scientific community. This project will support and train a graduate student at New Mexico Tech, aminority-serving institution. In addition, the Principal Investigator will work with New Mexico Tech's Alliance for Minority Participation (AMP) program to recruit a minority undergraduate research assistant. This program helps to match faculty with students interested in research experience and mentoring towards graduate school.