Tsunamis: Landslide Generated Waves and Run-up and Landward Inundation

9523414 Raichlen本项目涉及与海啸造成的损害有关的两个领域，即海啸的产生和沿海影响。 海啸是由海底发生的地震、山体滑坡和火山爆发等脉冲事件产生的海浪。 海啸问题可分为三个方面：产生、传播和海岸影响。 本次调查是针对减轻海啸的危险，主要是由于近岸水下滑坡。 在加州，许多海底峡谷垂直于海岸，峡谷顶部靠近海岸，储存在这些峡谷的近海岸区域的沉积层的水下滑动可能产生大浪。 可能造成这种山崩的一个重要机制可能是远处或近海地震，例如1994年1月北岭地震，该地震在距离震中约20英里的圣莫尼卡沿海社区造成相当大的震动和破坏。 如果这样的震动触发了近岸峡谷沉积层的破坏，就有可能在近岸沃茨产生破坏性的海啸。 水下滑坡产生的波浪的形状和运动学特性及其在向海岸和陆地传播时的变化对于确定可能处于这种潜在破坏性波浪路径上的结构（如海堤和建筑物）上的力非常重要。 该项目包括通过水下沉积物滑坡了解海啸生成机制的实验，同时开发生成机制的分析模型。 它将提供数据，以协助评估淹没距离，预测沿海洪水，并建议可靠的限制疏散区。 这些数据对工程设计、城市规划和海啸预警系统的改进具有重要意义。 结果也将直接适用于与其他波结构相互作用，如长波长风暴波的向岸传播，并在内陆水库和沿海入口滑坡产生的波相关的工程问题。 ***

9523414 Raichlen This project addresses two areas related to the damage resulting from tsunamis, namely generation and coastal effects. Tsunamis are ocean waves which are generated by impulsive events such as earthquakes, landslides, and volcanic eruptions occurring on the ocean bottom. The tsunami problem can be divided into three general areas: generation, propagation and coastal effects. This investigation is directed toward mitigation of the tsunami hazard primarily due to nearshore underwater landslides. In California, numerous submarine canyons are oriented perpendicular to the shore, with the canyon heads nearshore where the underwater sliding of sediment layers stored in the nearshore regions of these canyons could generate large waves. An important mechanism which could cause such landslides could be a distant or an offshore earthquake, such as the Northridge earthquake of January 1994 which caused considerable shaking and damage in the coastal community of Santa Monica, approximately 20 miles from the epicenter. If such shaking had triggered the failure of sediment layers in the nearshore canyons, it is possible that a damaging tsunami could have been generated in the nearshore waters. The shape and the kinematic properties of waves generated by underwater landslides and their modification as they propagate shoreward and overland are important in defining the forces on structures, such as seawalls and buildings which may be in the path of such potentially-destructive waves. The project involves experiments to understand the tsunami generation mechanism through underwater sediment slides, in conjunction with the development of an analytical model for the generation mechanism. It will provide data to assist in the evaluation of inundation distances to predict coastal flooding, and suggest reliable limits to evacuation zones. Such data are important for the engineering design, urban planning, and for improvement of the tsunami warning syste m. The results will be directly applicable also to engineering problems associated with other wave-structure interactions, such as the shoreward propagation of long-wavelength storm waves, and to waves generated in inland reservoirs and coastal inlets by landslides. ***