CO Editor

Suggestions for revision or reasons for rejection

The authors claim that their documentary data analysis to reconstruct the circumstances of landslide events occurring in historical times, is a significant methodological and scientific contribution of a pioneering nature. This is arguable, Geoarcheology is a well-established discipline. The geoarcheological approaches/techniques have been applied to the analysis of the occurrence of natural hazards on historical sites (e.g., Field & Banning, 1998 Geoarcheology, 13: 595-616; Bottari & Sepe, 2013: Quaternary Int. 309-309: 105-111). It is particularly well developed for the study of past earthquakes (e.g, Stiros, 2001-Jour. Structural Geology, 23: 545-562; Silva et al. 2005 Tectonophysics, 408: 129-146; Katz and Crouvi, 2007 Eng. Geology 95: 57-78; Rodriguez-Pascua et al. 2010 GSA Special Paper 471).
In any case, the main criticism to the submitted manuscript is that the analysis of the failure mechanism, the sedimentological and/or textural description of the rockfall deposits and the geological characterization of the source (predisposing factors), which must be based on evidences and field observations, is missing. This is why I recommend rejection.
The mechanism is unclear. Despite the case is described as a rockfall, the authors conclude it was a rockslide (lines 391-397). This conclusion is based exclusively on the estimated volume of the deposits rather than on the analysis the kinematic features either observed at the deposits themselves or at the detachment area. Which is arguable.
The authors state (lines 361-362) that any attempt to obtain the possible trajectories related to the Sclafani landslide would be unreliable. Moreover (lines 372-375 and answers to the reviewers), they consider that the deposits might have been eroded. Taking this into account, how can the runout length, shadow, and travel distance angles and volume be determined?
An event attaining 0.68 million cubic meters that occurred 160 year ago, should have left a visible scar at the source. In fact, many Holocene rockfalls scarps of similar size are still observable in the landscape. Unfortunately, no description of the rockfall source is provided in the text.
The statements on the role of the discontinuities in the instability (lines 270-276, 442-445) are not based on observations. A proper geomechanical or structural characterization of the rock cliff was not carried out. The authors mention (lines 296-299) that no published data are available about the level of fracturing of the bedrock and that slope is inaccessible. However, pictures S1 and S2 suggest otherwise. Rock mass outcrops may be accessed from castle and at the base of the cliff.
I invite the authors to have a look published works describing the deposits, the geological and the geomechanical contexts of ancient sites affected by landslides/rockfalls. These are some examples: Dykes, 2007 (Landslides,4: 279-290); Senatore et al. 2013 (Geoarcheology, 29:1-15); Fanti et al. 2013 (Landslides, 10: 409-420); Gigli et al. 2012 (NHESS, 12:1883-1903); Zarroca et al. 2014 (Landslides, 11: 655-671); Margottini et al. 2015 (Landslides, 12: 193-204); Gül et al 2016 (Environ. Earth Sci. 75: 1310)

RC1: 'Nice historic research', Anonymous Referee #1, 10 Feb 2017

AC1: 'answers to reviewer #1', Antonio Contino, 27 Feb 2017

RC2: 'Re: interactive discussion on the manuscript presented by A. Contino et al.', Anonymous Referee #2, 24 Feb 2017

AC2: 'answers to reviewer #2', Antonio Contino, 09 Mar 2017

Interactive discussion

Peer-review completion