Ancient Coastal Changes Due to Ground Movements and Human Interventions in the Roman Portus Julius (Pozzuoli Gulf, Italy): Results from Photogrammetric and Direct Surveys

Abstract

This research aims to evaluate the amount of vertical ground movements during Roman times inside the archaeological area of Portus Julius (Gulf of Pozzuoli) using high-precision surveys on the most reliable archaeological sea-level markers. Measuring the submersion of ancient floors, structural elements belonging to a former fish tank, and several roman pilae, two different relative sea levels (RSLs), related to the beginning and the end of the first century BCE, respectively, −4.7/−5.20 m and −3.10 m MSL (mean sea level), were detected. A photogrammetric survey was carried out in order to produce a 3D model of the fish tank. The results in terms of the RSL variations have enabled us to reconstruct a morpho-evolution of the ancient coastal sector during the last 2.1 kyBP. At the beginning of the first century BCE, the area was characterized by a sheltered gulf with numerous maritime villae located along the coast. In 37 BCE, the construction of the military harbour of Portus Julius strongly modified the paleogeography of the sector, which was also affected by a prevailing subsidence at least until the end of the first century BCE (year 12 BCE), when the port was converted into a commercial hub.

New Geomorphological and Historical Elements on Morpho-Evolutive Trends and Relative Sea-Level Changes of Naples Coast in the Last 6000 Years

“…In conclusion, this research, which belongs to a wider framework of studies concerning the Holocene landscape evolution of the Gulf of Naples [42][43][44][45]53,54,79,108,109], on one hand, improved the knowledge on the coastal landscape evolution of Naples and, on the other hand, provided new data on the VGM affecting this area and referable to the CF recent activity.…”

“…The city of Naples is located along the Tyrrhenian coasts, in the western sector of Campi Flegrei volcanic area [41]. This 60 ky old active volcano is known worldwide for the VGMs that have affected its territory in the last millennia and they have strongly influenced the Holocene evolution of its coasts [47][48][49][50][51][52][53][54].…”

“…The fundamental structural element that was used to evaluate the relative seal level (RSL) in this period was a well-preserved walkway, nowadays positioned at −1.8 m MSL. When considering that the functional clearance of this element with respect the ancient high tide (MHW, sensu Shennan, [24]) has been evaluated in 0.2 m by several authors (Aucelli et al [53] and reference therein), a RSL at −2.2 m during the first century BC was deduced.…”

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

“…Several studies have been carried out on specific sectors of the Campi Flegrei coast, e.g., the Monte di Procida sea cliff [13], the Miseno Cape [14], the gulf of Pozzuoli [15], and the Posillipo promontory [16]. These studies highlighted the role of ground motions, e.g., bradyseism, besides rock-types, volcano-tectonics, and climate, in shaping the coastline.…”

Characteristics and coastal effects of a destructive marine storm in the Gulf of Naples (Southern Italy)

“…During the Holocene, the morpho-evolutive trends of the coasts of the Gulf of Naples has been characterized by sudden coastal changes strongly related to the interplay between glacio-isostatic sea level rise and volcanic forcing (Cinque et al, 2011;Aucelli et al, 2020Aucelli et al, , 2019Aucelli et al, , 2018aMattei et al, 2020). The latter was driven by the combined effects of volcanic eruptions with consequent landscape mantling by pyroclastic products, and vertical ground movements of metric entity related to sudden uplift for inflating and subsidence for deflating of the magmatic chamber.…”