Integrated dataset of deformation measurements in fractured volcanic tuff and meteorological data (Coroglio coastal cliff, Naples, Italy)

Abstract

Abstract. Along the coastline of the Phlegraean Fields volcanic district, near Naples (Italy), severe retreat processes affect a large part of the coastal cliffs, mainly made of fractured volcanic tuff and pyroclastic deposits. Progressive fracturing and deformation of rocks can lead to hazardous sudden slope failures on coastal cliffs. Among the triggering mechanisms, the most relevant are related to meteorological factors, such as precipitation and thermal expansion due to solar heating of rock surfaces. In this paper, we present a database of measurement time series taken over a period of ∼4 years (December 2014–October 2018) for the deformations of selected tuff blocks in the Coroglio coastal cliff. The monitoring system is implemented on five unstable tuff blocks and is formed by nine crackmeters and two tiltmeters equipped with internal thermometers. The system is coupled with a total weather station, measuring rain, temperature, wind and atmospheric pressure and operating from January 2014 up to December 2018. Measurement frequencies of 10 and 30 min have been set for meteorological and deformation sensors respectively. The aim of the measurements is to assess the magnitude and temporal pattern of rock block deformations (fracture opening and block movements) before block failure and their correlation with selected meteorological parameters. The results of a multivariate statistical analysis of the measured time series suggest a close correlation between temperature and deformation trends. The recognized cyclic, sinusoidal changes in the width (opening–closing) of fractures and tuff block rotations are ostensibly linked to multiscale (i.e., daily, seasonal and annual) temperature variations. Some trends of cumulative multi-temporal changes have also been recognized. The full databases are freely available online at: https://doi.org/10.1594/PANGAEA.896000 (Matano et al., 2018) and https://doi.org/10.1594/PANGAEA.899562 (Fortelli et al., 2019).

Distributed Optical Fiber Sensor Applications in Geotechnical Monitoring

“…This is also confirmed by independent measurements performed with traditional crackmeters and reported in Ref. [23], where long-term (from 2014 to 2018) monitoring results from the same tuff cliff are reported. In particular, block n. 19 exhibited an alternating behavior (due to meteorological conditions), but with a clear prevalence of negative deformations, corresponding to a progressive closure of the fracture.…”

Geomorphological and Structural Assessment of the Coastal Area of Capo Faro Promontory, NE Salina (Aeolian Islands, Italy)

“…In this context, the geomorphological evolution induces a rapid cliff retreat, which triggers rockfalls and topples exploiting the discontinuities network [5][6][7] in the volcanic rock mass (e.g., joints and faults). Techniques in all fields of geology have been already explored in similar cases in the southern Italian peninsula [8][9][10][11][12][13], to define the hazardous conditions that could even provoke injuries or fatalities. Assessing these conditions, it is possible to find the best solution to address the risk mitigation measures or to fix them where they become ineffective, in a broad scenario of coastal management [14][15][16].…”

Geomorphological Approach to Cliff Instability in Volcanic Slopes: A Case Study from the Gulf of Naples (Southern Italy)

“…These studies highlighted the role of ground motions, e.g., bradyseism, besides rock-types, volcano-tectonics, and climate, in shaping the coastline. Furthermore, researches along the Posillipo promontory have been focused on very specific areas, such as the Nisida island [17], the Coroglio sea cliff [18], and the Marechiaro area [19]. Researches on the Posillipo promontory have also pointed out that this amazing portion of the Campi Flegrei coastline has attracted human frequentation since historical times [17,19].…”

“…We adopted a heuristic criterion and analyzed the main predisposing factors occurring in the study area. Our aim is not to propose a new method to assess susceptibility but only to present a case study that may be a useful example and source of data for further studies on the stability of similar volcanic coastal cliffs [13,16,18,27].…”