Drivers and modulators of collisional tectonics and their impact on geohazards

了解构造板块力的分布是预测未来全球地震活动的关键。虽然由于板块相对运动产生的作用力，地震大多发生在构造板块边缘，但它们也可能由远程力、板块内部运动和气候影响引起，这些研究很少。传统的板块构造理论认为，山带是由地壳沿着收敛的板块边缘压缩和增厚而形成的。然而，理论和观测研究表明，变形也发生在板块内部。山脉边界的碰撞力与驱动板块运动的力相反。这种对抗作用将应力传递到板块内部，造成板块内部变形，并可能导致板块解体。相反，构造板块的破裂会减少传递到碰撞边缘的力，从而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，解释构造变形如何在板块边缘和内部之间划分；2)确定板块尺度应力如何从早期破碎区传播到碰撞区；3)确定远处的力是否影响沿碰撞板块边界的应力。在本专题研究项目中，结合观测和理论框架，我们选择喜马拉雅地区作为研究对象，因为：(a)可以直接观测到上地壳变形；(b)控制褶皱冲断带变形和形态的参数已经建立；(c)单向湿源可以更简单地研究气候参数；(d)印度板块目前正在印度洋内的疑似分裂带变形。***该计划提出多个假设，由研究生领导的多学科项目进行测试。项目包括地震资料的汇编、综合和解释；板缘和板内力的计算；造山带演化的数值模拟；以及详细的实地研究。喜马拉雅地区压力的分布和程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地震灾害的监测和预测。从更广泛的意义上说，该项目研究了世界各地俯冲大地震与板块内和沿俯冲边缘的应力载荷之间的潜在动态联系，包括类似加拿大西部卡斯卡迪亚的类似环境

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.**