Drivers and modulators of collisional tectonics and their impact on geohazards

碰撞构造的驱动因素和调节因素及其对地质灾害的影响

• 批准号: RGPIN-2015-04311
• 负责人: Grujic, Djordje
• 金额: $ 1.97万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612893
• 关键词: Drivers; modulators; collisional; tectonics; their

Understanding distribution of tectonic plate forces is key to predicting future earthquake activity around the globe. Although earthquakes mostly occur at tectonic plate edges due to the forces generated by relative movements of the plates, they can also be caused by remote forces, interior plate movements, and climatic effects that are poorly studied. Conventional plate tectonics assumes that mountain belts form by compression and thickening of Earth’s crust along convergent plate margins. Yet theoretical and observational studies show that deformation also occurs in plate interiors. Collisional forces at mountainous boundaries oppose forces driving plate movement. This antagonism transmits stress into plate interiors, causing intraplate deformation and potentially leading to the disintegration of a plate. Conversely, breakup of a tectonic plate will reduce the amount of force transmitted to a collisional margin, influencing the amount of deformation and earthquake activity there. Although documented, these connections and feedback mechanisms remain unclear. The project’s scientific contributions and long-term objectives will: 1) Develop a theory explaining how tectonic deformation is partitioned between plate margins and interiors; 2) Determine how plate-scale stress propagates from incipient breakup areas to collision zones; and 3) Ascertain whether distant forces influence stress along colliding plate boundaries. For this thematic research program, combining observational and theoretical framework, we chose to study the Himalayan region because (a) upper crustal deformation can be directly observed; (b) parameters controlling deformation and morphology of the fold-and-thrust belt are well established; (c) unidirectional moisture sources allow simpler investigation of climatic parameters; and (d) the Indian plate is currently deforming at suspected breakup zones within the Indian Ocean. The program proposes multiple hypotheses to be tested by multidisciplinary projects led by graduate students. Projects include compilation, synthesis and interpretation of seismic data; calculation of plate margin and plate interior forces; numerical simulations of orogenic wedge evolution; and detailed field studies. The distribution and magnitude of stresses in the Himalayan region is not merely an academic issue. A deeper understanding of stress propagation and deformation across the Himalaya will improve monitoring and prediction of seismic hazards. In broader terms, this program addresses potential dynamic links between subduction mega-earthquakes and stress loading within plates and along subduction margins around the world, including similar settings like the Cascadia of western Canada.

了解构造板力的分布是预测全球未来地震活动的关键。虽然地震大多发生在构造板块边缘，这是由于板块相对运动产生的力，但也可能是由远距离力、板块内部运动和气候效应引起的，这些因素研究得很少。传统的板块构造理论认为，山带是由地壳沿着会聚的板块边缘挤压和增厚而形成的。然而，理论和观测研究表明，变形也发生在板块内部。山体边界的碰撞力与驱动板块运动的力相反。这种对抗性将应力传递到板的内部，导致板内变形，并可能导致板的解体。相反，构造板块的分裂将减少传递到碰撞边缘的作用力，影响那里的变形量和地震活动。尽管有文献记载，但这些联系和反馈机制仍然不清楚。 该项目的科学贡献和长期目标将：1)发展一种理论，解释板块边缘和内部如何划分构造变形；2)确定板块规模的应力如何从初始解体区域传播到碰撞带；以及3)确定远距离力是否影响碰撞板块边界上的应力。对于这一专题研究计划，结合观测和理论框架，我们选择研究喜马拉雅地区，因为(A)可以直接观测到地壳上部的变形；(B)控制褶皱冲断带的变形和形态的参数已经建立得很好；(C)单向水汽来源使气候参数的研究变得更简单；以及(D)印度板块目前在印度洋内疑似解体带处变形。 该项目提出了多个假说，由研究生领导的多学科项目进行检验。项目包括地震数据的汇编、合成和解释；板块边缘和板块内力的计算；造山楔演化的数值模拟；以及详细的实地研究。喜马拉雅地区的应力分布和强度不仅仅是一个学术问题。更深入地了解喜马拉雅地区的应力传播和变形将改善对地震灾害的监测和预测。从更广泛的意义上说，这个项目解决了俯冲大地震与世界各地板块内和俯冲边缘沿线的应力加载之间潜在的动态联系，包括加拿大西部的卡斯卡迪亚这样的类似环境。