Читать книгу Monument Future - Siegfried Siegesmund - Страница 326

Many social and religious traditions of Japan are deeply rooted in the underground landscape. Over the centuries, sacred hypogea have been frequented for Buddhist and Shinto practices and for burials, caves used as shelters during wars and persecutions, 222tunnels excavated for raw-material exploitation or industrial manufacturing. This study concerns man-made cave sites in central Japan (Kanto region) of diverse age, from the Kofun, about 1,500 years ago, through the Kamakura and Edo periods (13–19th century), until the modern era. They were dug into soft and porous sedimentary rocks, namely volcanic tuffs and tuffaceous mudrocks, which show varied signs of decay, related to salt weathering and water interaction. The first results of the characterization of the textural, mineralogical, petrophysical, and chemical properties of the rock and its weathering products are presented here. The vulnerability of the underground sites is correlated with the relevant environmental conditions, by the monitoring of air temperature and relative humidity. The secondary phases forming crusts and efflorescences on the cave surfaces are mostly sulfates of diverse chemistry. A critical parameter determining their crystallization, stability, or deliquescence is relative humidity, often extremely high, while their composition is controlled most notably by rock mineralogy. The eventual outcomes of this research are expected to support the adoption of countermeasures for preserving and promoting the underground cultural heritage and stone artifacts enshrined therein, and give indications about the influence and safety of visitor traffic.

Keywords: Anthropic cave; Stone decay; Microclimatic monitoring.