Collaborative Research: The Burma Arc from Collision Kinematics to Subduction Tectonics as Observed from a Passive seismic experiment (BACKSTOP)

当两块构造板块相撞时，其中一块可能会滑到另一块下面。这一过程称为俯冲，通常在大洋板块与大陆板块相遇时发生。俯冲的大洋板块或俯冲板块下沉到地幔中，影响区域地幔流动。这通常会在陆地上产生造山和火山活动，比如在卡斯卡迪亚和安第斯山脉。这些火山可能沿着一条称为弧形的曲线链形成。大陆板块的碰撞也形成了山脉，比如阿尔卑斯山和喜马拉雅山脉。这些过程导致了威胁人类生命和活动的大地震和火山喷发。在这里，研究人员研究了板块边界俯冲与大陆碰撞的耦合。印度洋板块的俯冲发生在印缅弧线上。它过渡到沿喜马拉雅山脉相撞。科学家们利用五个国家和美国之间的国际合作。他们利用地震学，即研究通过地球传播的地震波，在3D地幔和地壳结构中成像。他们在缅甸的关键地点部署了24个地震台，分析来自这些仪器以及周边印度、孟加拉国和中国的约900个地震台的数据。一个主要目标是揭示青藏高原东南部生长的过程。另一个是量化印度板块几何形状对地幔流动的影响。该项目提高了对区域构造的理解。它的结果对缅甸的地震和火山危险评估有很大的影响，缅甸是一个面临重大戏剧性事件的地区。该项目为密苏里州和新墨西哥州的两名研究生提供支持，并在缅甸开展科学合作。这项为期三年的奖项是由NSF极端事件预测和抵御极端事件(PREEVENTS)计划共同资助的。在这里，研究小组调查了缅甸地下的印度板块作为东喜马拉雅地区地幔流动的“后盾”的作用。他们还研究了这如何影响青藏高原东南部的增长。该项目由两部分组成：(1)从连接印度/孟加拉国和中国大型地震台阵的临时地震台阵收集数据；(2)综合该地区大量现有台站的数据。数据采集部分由部署在没有任何地震仪器的关键地区的24个临时宽带站组成。第二部分是与缅甸、印度、新加坡、中国和德国科学家的合作努力。由900多个台站组成的联合地震台网覆盖了1800公里乘2000公里的区域。它完全覆盖了整个印缅弧线。科学家们使用三维地震层析成像技术和各向异性表面波层析成像技术对印缅俯冲带下的印度板块进行成像。这使得他们能够比较东喜马拉雅山脉和印度-缅甸弧后地区的流动和岩石圈变形。该项目的成果限制了与印度碰撞和俯冲相关的形变动力学，以及从俯冲到大陆碰撞的过渡如何发生。对区域构造以及地壳衰减的洞察，是改进缅甸及周边地区地震和火山灾害预测的关键。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

When two tectonic plates collide, one may slide underneath the other. This process, called subduction, often occurs when an oceanic plate meets a continental plate. The subducting oceanic plate, or subducting slab, sinks into the Earth's mantle affecting the regional mantle flow. This often generates mountain building and volcanic activity on land, like in Cascadia and Andean mountains. The volcanos may form along a curved chain called an arc. Colliding continental plates also build mountain ranges, like the Alps and the Himalayas. These processes are responsible for large earthquakes and volcanic eruptions threatening human lives and activity. Here, the researchers study a plate boundary coupling subduction with continental collision. Subduction of the Indian oceanic plate occurs along the Indo-Burma arc. It transitions to collision along the Himalayan Mountains. The scientists leverage on an international collaboration between five countries and the U.S. They use seismology, the study of seismic waves propagating through the Earth, to image in 3D mantle and crustal structures. Deploying 24 seismic stations in key locations in Myanmar, they analyze data from these instruments and ~900 other stations in surrounding India, Bangladesh and China. A primary objective is to unveil the processes responsible for the growth of the southeastern Tibetan Plateau. Another one is to quantify the effect of the Indian slab geometry on the mantle flow. The project improves the understanding of the regional tectonics. Its outcomes have strong implications for seismic and volcanic hazard assessment in Myanmar; a region which faces large dramatic events. The project provides support for two graduate students in Missouri and New Mexico, as well as the development of scientific collaborations in Myanmar. The three-year award was co-funded by NSF Prediction of and Resilience against Extreme Events (PREEVENTS) program. Here, the team investigates the role of the Indian slab beneath Burma as a "backstop" to the mantle flow around the eastern Himalayas. They also study how this impacts the growth of the southeastern Tibetan Plateau. The project consists of two components: (1) data collection from a temporary seismic array that links large arrays in India/Bangladesh and China; (2) the synthesis of data from a large number of existing stations across the region. The data acquisition component consists of 24 temporary broad-band stations deployed in key regions lacking any seismic instruments. The second component is a collaborative effort with scientists from Myanmar, India, Singapore, China, and Germany. The combined seismic network of over 900 stations spans an area of 1800 km by 2000 km. It completely covers the entire Indo-Burma Arc. The scientists use 3-D seismic tomography and anisotropic surface wave tomography to image the Indian slab beneath the Indo-Burma subduction zone. This enables them to compare flow and lithospheric deformation around eastern Himalayas and in the Indo-Burma back-arc. The project outcomes constrain the dynamics of the deformation associated with the Indian collision and subduction, and how the transition from subduction to continental collision occurs. The gained insight into the regional tectonics, as well as crustal attenuation, is key to improve seismic and volcanic hazard forecasting in Myanmar and surrounding regions.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.