The study of coastal boulder accumulations generated by extreme marine events, and of the energy and frequency involved in boulder transport, is of paramount importance in understanding the risk associated with extreme marine inundations. One of the frequently asked questions is whether the deposits are storm or tsunami-related, both events being characterized by different return periods. Boulder transport by storms was monitored on the west coast of Portugal. Significant changes were detected in boulders' position as a result of extreme inundation by the 2013/2014 winter storms. Results presented in this work indicate that the wave power associated with the “Christina” and “Nadja” storms occur once every three years. However, this interval is not supported by field observations of boulder displacement, which suggests that wave power over-predicts boulder movement in the study area. Furthermore, wave parameters from the “Christina” and “Nadja” storms were very similar, but have generated different impacts in the boulder accumulation described herein. Differences include the magnitude and direction of boulder movement, and are most likely associated with distinct tidal levels during the events. Higher tide levels generated an increase in the sea surface level and thus in the reach of waves, which generated displacement of larger boulders and consequent cross-shore contribution in boulder transport. Regardless, the combination of monitoring campaigns, wave data, and statistical modelling of extreme values indicate that boulder transport by storms is more frequent than initially expected. Based on recorded boulder movements, we present a conceptual model for boulder ridge formation and development and identify significant control of incoming flow by local geomorphological/topographical features. Storm events, not less frequent tsunamis, are identified as the events responsible for modulating this rocky coastline. These results question a direct attribution of coastal boulder deposits to tsunamis in coastal regions with a high risk of tsunami inundation.

由极端海洋事件产生的沿海巨石堆积以及巨石运输所涉及的能量和频率的研究对于理解与极端海洋淹没相关的风险至关重要。常见问题之一是这些沉积物是否与风暴或海啸有关，这两个事件的特点是回报期不同。在葡萄牙西海岸对暴风雨造成的巨石运输进行了监测。2013/2014年冬季暴风雪极大地淹没了巨石的位置，发现了重大变化。这项工作提出的结果表明，与“克里斯蒂娜”和“纳迪亚”风暴有关的波浪功率每三年发生一次。但是，实地观测巨石位移并不能支持该间隔，这表明波浪能高估了研究区域内的巨石运动。此外，来自“克里斯蒂娜”和“纳迪亚”风暴的波浪参数非常相似，但是对本文所述的巨石堆积产生了不同的影响。差异包括巨石运动的幅度和方向，并且很可能与事件期间不同的潮汐水平有关。较高的潮汐水平使海平面上升，从而使波浪作用范围增大，从而使较大的巨石发生位移，从而在巨石运输中产生了跨岸影响。无论如何，监测活动，海浪数据和极值的统计模型的组合表明，风暴造成的巨石运输比最初预期的要频繁。根据记录的巨石运动，我们提出了巨石山脊形成和发展的概念模型，并通过局部地貌/地形特征确定了对来水的重大控制。暴风雨事件，而不是较少的海啸，被认为是造成这条多岩石的海岸线发生变化的事件。这些结果质疑了沿海巨石沉积物直接归因于海啸淹没风险高的沿海地区的海啸。