3D Modelling of Archaeoseismic Damage in the Roman Site of Baelo Claudia (Gibraltar Arc, South Spain)

Abstract

This study deals with the morphometric characterization and quantification of earthquake damage in the ancient Roman city of Baelo Claudia in South Spain (Gibraltar Arc) by means of the use of 3D modelling from drone imagery. Baelo Claudia is a world-renowned archaeological site recording recurrent earthquake destruction during the first and third centuries AD. The first earthquake destroyed the lower littoral zone of the city, allowing its reconstruction from the year c. 60–70 CE, but the second earthquake in 365–390 CE led to the complete destruction of the renewed city and its eventual abandonment. This second earthquake imprinted important deformations in the main monumental zone of the city, including the basilica temples, macellum, city walls, aqueducts and funerary monuments, as well as in the main paved zones of the city. This is the case for the Forum, Decumanus and Cardos, which show a variety of folds, pop-up structures, conjugate fractures and impact marks susceptible to be measured in a 3D format. The current study presents detailed (up to 3 mm/pixel) surface models of iconic monuments within the city. The 3D models were obtained by means of serial orthophotos taken with a UAV Mavic Pro 2 (DJI) Drone device equipped with a 20 mpx camera and a 1” CMOS sensor. Each individual image was captured in a geo-referenced jpg format and processed with the Agisoft Metashape Professional software®. Depending on the measured monument, the final images consisted of 250 to 700 photographs clustered by 50,000 to 150,000 tie points. In all studied items (Decumanus, city walls and bath dish), we follow the same workflow of analysis: (1) alignment of photos with support points; (2) building a dense cloud of points; (3) creation of the surface texture; (4) creation of the Digital Elevation Model (DEM); (5) creation of the orthomosaic; and finally, (6) the building of the high-quality 3D tiled surface models. The obtained models allow the geometric quantification of earthquake deformations (displacements, amplitudes, orientation, etc.) in a GIS-based 3D environment suitable to quantify oriented damage of seismic origin. In a complementary way, these 3D models deserve to be considered for their potential role as digital seismoscopes of ancient archaeological sites and/or heritage buildings.

Geología y Arqueología del Terremoto-Tsunami de finales del Siglo IV a.C. que destruyó la ciudad Romana de Baelo Claudia (Cádiz, Sur España)

“…Los pliegues se encuentran extendidos a lo largo de todo el Decumanus, y la mayoría de ellos presentan orientaciones similares a las definidas en el mercado y en la zona sur de la Foro y en la plaza de la Basílica (Silva et al, 2009;Giner-Robles et al, 2013). El análisis del modelado digital de las deformaciones del decumano muestran direcciones y amplitudes de plegamiento muy acordes a las de ondas sísmicas superficiales provenientes del SSO (Sánchez-Sánchez et al, 2022). No obstante, también se registran estructuras plegadas y subsidencias más marcadas condicionadas por la presencia de estructuras de drenaje subterráneas (Giner-Robles et al, 2017).…”

Metaverse for Cultural Heritages

“…Selim et al [42] thought that integrating both human and digital records enriched the virtual twin of cultural heritage sites, as a living and more humane experience that best represents the relevant multi-layered and overlapping history and cultural practices. Sánchez-Sánchez et al [43] applied 3D modelling and DT for archaeo-seismic damage research at the Roman site of Baelo Claudia. With the application of HBIM, Wang and Wu [44] worked on an efficient solution for online education concerning the risks posed by the ongoing COVID-19 pandemic.…”