M. Fraters, M. Billen, J. Naliboff, L. Staisch, J. Watt, Haoyuan Li
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引用次数: 0
Abstract
Subduction zones are home to multiple geohazards driven by the evolution of the regional tectonics, including earthquakes, volcanic eruptions and landslides. Past evolution builds the present-day structure of the margin, while the present-day configuration of the system determines the state-of-stress in which individual hazardous events manifest. Regional simulations of subduction zones provide a tool to synthesize the tectonic history of a region and investigate how geologic features lead to variations in the state of stress across the subduction system. However, it is challenging to design regional models that provide a force-balance that is consistent with the large-scale motion of surrounding tectonic plates while also not over-constraining the solution. Here, we present new models for the Cascadia subduction zone that meet these criteria and demonstrate how the motion of the subducting Juan de Fuca plate can be used to determine the along-strike variations in the viscous (long-term) coupling across the plate boundary. All successful models require lower viscous coupling in the northern section of the trench compared to the central and southern sections. However, due to uncertainties in the geometry of the Cascadia slab, we find that there is a trade-off between along-strike variation in viscous coupling and slab shape. Better constraints on the slab shape, and/or use of other observations are needed to resolve this trade-off. The approach presented here provides a framework for further exploring how geologic features in the overriding plate and the properties of the plate boundary region affect the state-of-stress across this and other subduction zones.
俯冲带是由区域构造演化驱动的多种地质灾害的家园,包括地震、火山爆发和山体滑坡。过去的进化建立了今天的边缘结构,而系统的当前配置决定了个体危险事件显现的压力状态。俯冲带的区域模拟提供了一种工具来综合一个地区的构造历史,并研究地质特征如何导致整个俯冲系统的应力状态变化。然而,设计区域模型是一项挑战,该模型既能提供与周围构造板块的大规模运动相一致的力平衡,又不会过度限制解决方案。在这里,我们提出了符合这些标准的Cascadia俯冲带的新模型,并展示了如何利用俯冲Juan de Fuca板块的运动来确定沿板块边界的粘性(长期)耦合的沿走向变化。所有成功的模型都要求海沟北部的粘性耦合比中部和南部低。然而,由于卡斯卡迪亚平板几何形状的不确定性,我们发现在沿走向的粘性耦合变化和平板形状之间存在权衡。需要更好地约束板坯形状,和/或使用其他观测来解决这种权衡。本文提出的方法为进一步探索上覆板块的地质特征和板块边界区域的性质如何影响这个和其他俯冲带的应力状态提供了一个框架。
期刊介绍:
Geochemistry, Geophysics, Geosystems (G3) publishes research papers on Earth and planetary processes with a focus on understanding the Earth as a system. Observational, experimental, and theoretical investigations of the solid Earth, hydrosphere, atmosphere, biosphere, and solar system at all spatial and temporal scales are welcome. Articles should be of broad interest, and interdisciplinary approaches are encouraged.
Areas of interest for this peer-reviewed journal include, but are not limited to:
The physics and chemistry of the Earth, including its structure, composition, physical properties, dynamics, and evolution
Principles and applications of geochemical proxies to studies of Earth history
The physical properties, composition, and temporal evolution of the Earth''s major reservoirs and the coupling between them
The dynamics of geochemical and biogeochemical cycles at all spatial and temporal scales
Physical and cosmochemical constraints on the composition, origin, and evolution of the Earth and other terrestrial planets
The chemistry and physics of solar system materials that are relevant to the formation, evolution, and current state of the Earth and the planets
Advances in modeling, observation, and experimentation that are of widespread interest in the geosciences.