Landslides and surface erosion are major processes controlling the progressive recession of many rocky cliffs along the Italian coastline. Nevertheless, many coastal settlements were built along cliffed sectors prone to rapid collapses. This represents a serious risk for tourists and living people, as well as for buildings, roads and railway networks. The densely urbanized coastline of the Campi Flegrei active volcanic district is one of the rocky coastal areas of South Italy mostly exposed to the recession. Here, coastal cliffs are made by volcaniclastic deposits and include remnants of ancient volcanic edifices formed in the last 15 ka. Due to petrographic, geotechnical and geostructural properties of volcaniclastic deposits, these cliffs have been affected by rapid recession since their origin. This research focuses on a cliff of the Campi Flegrei coastaline (Torrefumo, Monte di Procida) which, although currently protected from the sea waves by a seawall, is still retreating. We assessed the ongoing recession using a change detection analysis, based on accurate topographic data acquired with two terrestrial laser scanning surveys executed in 2013 and 2016. The quantitative comparison of 3D point clouds datasets allowed detecting 191 cliff failures. We verified that the frequency-magnitude distribution of the detached blocks followed an inverse power law, and most of the involved volumes were between 0.01 and 1 m³. Retreat rates of different cliff sectors varied from 0.001 to 0.025 m/year. Our analysis also allowed us to recognize slope failure mechanisms and distinguish rock falls from grain-by-grain surficial erosion.

中文翻译：

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表征沿海悬崖的部分失效机理和频率大小统计数据免受波浪侵蚀作用

滑坡和表面侵蚀是控制意大利海岸线上许多岩石峭壁逐渐衰退的主要过程。然而，许多沿海居民区是在容易迅速倒塌的悬崖峭壁上建造的。这对游客和在世人员以及建筑物，道路和铁路网构成了严重的风险。Campi Flegrei活跃火山区密集的城市化海岸线是意大利南部多岩石的沿海地区之一，最容易受到经济衰退的影响。在这里，沿海悬崖是由火山碎屑沉积物形成的，其中包括在最后15 ka形成的古老火山构造的残留物。由于火山碎屑岩的岩石学，岩土工程和岩土结构特性，这些悬崖自形成以来就受到快速衰退的影响。这项研究的重点是Campi Flegrei沿海地区的悬崖（Torrefumo，蒙特迪普罗奇达），尽管目前受到海堤的保护，但仍在撤退。我们根据2013年和2016年进行的两次地面激光扫描测量获得的准确地形数据，使用变化检测分析评估了持续的衰退。3D点云数据集的定量比较可检测到191次悬崖破坏。我们验证了分离块的频率幅度分布遵循幂次定律，并且所涉及的大部分体积在0.01和1 m之间 基于2013年和2016年执行的两次地面激光扫描调查获得的准确地形数据。3D点云数据集的定量比较可以检测到191个悬崖故障。我们验证了分离块的频率幅度分布遵循幂次定律，并且所涉及的大部分体积在0.01和1 m之间 基于2013年和2016年执行的两次地面激光扫描调查获得的准确地形数据。3D点云数据集的定量比较可检测到191个悬崖故障。我们验证了分离块的频率幅度分布遵循幂次定律，并且所涉及的大部分体积在0.01和1 m之间³。不同悬崖扇形区的退缩速率从0.001到0.025 m /年。我们的分析还使我们能够认识到边坡的破坏机理，并可以将岩石崩落与逐粒表面侵蚀区别开来。