Fluctuation analysis of the time dynamics of laser distance data measured in the medieval Jeronym Mine (Czech Republic)

Fractal tools are used to investigate the hourly time fluctuations of the ceiling height of a chamber located in the medieval Jeronym Mine, which is one of the Cultural National Heritage sites of the Czech Republic. The data were measured from 2008 to 2010 by a laser distance meter (Leica DISTO (TM) A4). The scaling behavior is revealed by means of different statistics: the power spectrum method, the detrended fluctuation analysis, the Higuchi analysis and the mean distance spanned within time L. The values of the scaling exponents estimated by means of these methods indicate that the temporal fluctuations of the ceiling height are not typical of a purely random stochastic process (i.e. white noise), but evidence the presence of long-range correlations. Furthermore, it is found that these correlations are linear.