Understanding the deformation and processes that link ductile flow in the deep continental crust with frictional processes in the upper crustal seismogenic zone

了解将深部大陆地壳中的延性流与上地壳地震带中的摩擦过程联系起来的变形和过程

• 批准号: RGPIN-2020-05658
• 负责人: Grujic, Djordje
• 金额: $ 2.19万
• 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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=717791
• 关键词: Understanding; deformation; processes; link; ductile

Subduction zonesregions of Earth's crust where one tectonic plate dives beneath anotherare usually but not always associated with frequent, violent earthquakes. Occasionally, the downgoing plate slides slowly, smoothly and almost silently under the overriding plate. Canadian scientists have contributed to the research of seismic slow signals with geophysical observations of the Cascadia subduction zone. However, field observations, rock experiments and theoretical developments are also needed to advance our understanding of these newly identified fault slip phenomena. The proposed research program, with implications for future earthquakes offshore western Canada, aims to (a) expand our knowledge of mechanical processes that link mega earthquakes in the upper crust to steady and continuous slip in the lower crust via the brittle-ductile transition zone, which hosts the seismic slow signals, and (b) test a set of innovative methods to determine the ages of pre-instrumental earthquakes. (a) The importance of this research lies in the potential relationship between the fault transition zone and the parts of faults that generate destructive earthquakes. Some calculations find that the probability of a large earthquake occurring during a slow-slip event is 30100 times greater than background probabilities. My research program involves interdisciplinary studies of exemplary exposed megathrust systems that record different stages of their development. Continental megathrust systems will be investigated via integration of observations across a range of scales and approaches, including field studies, microanalyses, thermochronology, geochronology, and numerical modelling. (b) Deformation data obtained from faulted rocks should be interpreted in the context of temporal or spatial variations in seismic processes. Thus, precise and accurate dating is crucial and entails developing innovative techniques that directly link age data to evidence of seismic slip in the rock record. This goal is achievable because of recent developments in our understanding of the physics of signals from minerals released via exposure to heat produced by seismic slip, and improvements in related analytical methods. To test the new techniques, we selected several locations where a surface earthquake rupture of known age provides access to samples suitable for attaining this goal. In addition to taking a leadership role in the discipline, Canada will benefit from this research by further understanding the processes responsible for Earth's major evolutionary steps, which can then feed into policy development for geohazard and environmental protection. Program goals will involve Canadian and international collaborators and train 2 PhD and 2 MSc graduate students, 1 PDF and undergraduates who will become knowledgeable in science communication and international and earthquake research, collaborate with world-leading research groups and gain access to world-class infrastructure.

俯冲带一个构造板块俯冲到另一个板块之下的地壳区域，通常但并不总是与频繁的剧烈地震有关。偶尔，下行板块会缓慢、平稳、几乎无声地在上覆板块下方滑动。加拿大科学家通过对卡斯卡迪亚俯冲带的地球物理观测，对地震慢信号的研究做出了贡献。然而，还需要实地观测、岩石实验和理论发展来推进我们对这些新发现的断层滑动现象的理解。拟议的研究计划对加拿大西部近海未来的地震有影响，其目的是(a)扩大我们对机械过程的认识，该过程通过承载地震慢信号的脆性-韧性过渡带将上地壳的特大地震与下地壳的稳定和连续滑动联系起来，(b)测试一套确定仪器前地震年龄的创新方法。