Siegfried Siegesmund - Monument Future

Their discrepancies are, on average, around 0.8 %, which is within the experimental error of the onset time picking measurements. However, these discrepancies increase for altered samples (2.9 %), which could be related to the surficial roughness and microstructure modification by crystallisation pressure and the presence of remaining salts.

As grain size and weathering increase, the determination of arrival time of S-waves becomes more problematic due to the contamination of S-waveforms by P-waves, a lower signal-to-noise ratio and an increase of wavelength. These difficulties are more prevalent in the weathered samples, where the manual picking of the onset-time becomes more difficult and time-consuming.

Despite experimental problems, S-wave velocity values are in agreement with previous published data for similar rock types. Therefore manual measurements can be considered as a “true” or reference value (e. g.: Siegesmund and Dürrast, 2011). When comparing manual and calculated S-wave values, it can be observed that the proposed methodology calculates accurate values S-wave velocity of the studied rock types (Fig. 3). Discrepancies between the manual and automatic methods are within experimental error of the onset time picking measurements of S waves velocities, with a discrepancy of around 5 %. Generally, V Svalues are slightly higher when calculated using the automatic method in comparison to the manual method (Fig. 3).

This methodology successfully distinguishes between P-waves and S-waves based on criteria relating to symmetry, amplitude and duration. One advantage of this method is the limitation of subjectivity of the human analyst. Moreover, this study has identified that the main peak frequency of P- and S-waves are comparatively different ( Table 1); a discrepancy that can be used as a further differentiating characteristic. This methodology is recommended for fresh and weathered stones with a medium-coarse grain size (0.5–1 mm). This methodology may be particularly helpful where the quality of the S-waveform signals are poor, resulting in difficulties with manual picking of the onset time.

This paper addresses determination of the picking of the onset of P- and S-waves in transmitted output waveforms on weathered sandstones. Stones weathered by salt crystallisation show an increase in surficial roughness and their microstructural properties are strongly modified by crystallisation pressure and the presence of remained salts. The wavelength of output signals depends on grain size and weathering, while microstructural components of stones and the presence of salts operate as a wavelength filter. Manual picking of the onset time for elastic waves becomes more difficult with increase in wavelength, although this observation is less important for P-waves than S-waves. Particularly, as grain size and stone alteration increase, the determination of arrival time of S-waves becomes more problematic due to the contamination of S-waveforms by P-waves, a lower signal-to-noise ratio and an increase of wavelength.

Figure 1: P signals for fresh and weathered samples for (a) Doddington sandstone, D; (b) Forest of Dean, F, measured in the parallel direction to bedding; and (c) St. Bees sandstone, BC.

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Figure 2: S signals for fresh and weathered samples for (a) Doddington sandstone, D; (b) Forest of Dean, F, measured in the parallel direction to bedding; and (c) St. Bees sandstone, BC.

Figure 3: Comparison of P (a) and S (b) wave velocities obtained manually (manual) and automatically (authomatic).

The automatic onset time from recording P- and S- waveforms is compared to manual picking, which is considered as a true or reference value. The discrepancies between automatic and manual measurements are within the experimental error of the onset time picking measurements.

This methodology is recommended for fresh and weathered stones with a medium-coarse grain size (0.5–1 mm). This methodology may be particularly helpful in samples where the quality of the S-waveform signals is poor, resulting in difficulties with manual picking of the onset time. The great advantage of this methodology is the accuracy and reproducibility of the obtained results, which do not depend on human subjectivity.

This project was supported by a mobility scholarship awarded by the University of Glasgow Graduate School, and Historic Environment Scotland for funding the attendance at Stone2020 and the Regional Government of Madrid (Spain) [Top Heritage, grant number S2018/NMT-4372].

Benavente, D., Galiana-Merino, J. J., Pla, C., Martinez-Martinez, J., Crespo-Jimenez, D., 2020. Automatic detection and characterisation of the first P- and S-wave pulse in rocks using ultrasonic transmission method. Engineering Geology, 66, 105474.

Benavente, D., Martinez-Martinez, J., Cueto, N., Ordonez, S., Garcia-del-Cura, M. A., 2018. Impact of salt and frost weathering on the physical and durability properties of travertines and carbonate tufas used as building material. Environ. Earth Sci. 77, 147.

Galiana-Merino, J. J., Rosa-Herranz, J. L., Rosa-Cintas, S., Martinez-Espla, J. J., 2013. SeismicWaveTool: Continuous and discrete wavelet yyysis and filtering for multichannel seismic data. Comput. Phys. Commun. 184, 162–171.

Sarout, J., Ferjani, M., Gueguen, Y., 2009. A semi-automatic processing technique for elastic-wave laboratory data. Ultrasonics 49, 452–458.

Siegesmund S., Dürrast H. (2011) Physical and Mechanical Properties of Rocks. In: Siegesmund S., Snethlage R. (eds) Stone in Architecture. Springer, Berlin, Heidelberg.

Wang, Q., Ji, S., Sun, S., Marcotte, D., 2009. Correlations between compressional and shear wave velocities and corresponding Poisson’s ratios for some common rocks and sulfide ores. Tectonophysics 469, 61–72.

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Hyeri Yang 1 , Dong Woo Kim 2 , Chan Hee Lee 1, Ji Hyun Yoo 3

IN: SIEGESMUND, S. & MIDDENDORF, B. (EDS.): MONUMENT FUTURE: DECAY AND CONSERVATION OF STONE.

– PROCEEDINGS OF THE 14TH INTERNATIONAL CONGRESS ON THE DETERIORATION AND CONSERVATION OF STONE –

VOLUME I AND VOLUME II. MITTELDEUTSCHER VERLAG 2020.

1Dept. of Cultural Heritage Conservation Sciences, Kongju National University, Gongju, 32588, Republic of Korea

2Chungbuk Research Institute of Cultural Heritage, Cheongju, 28443, Republic of Korea

3Conservation Science Division, National Research Institute of Cultural Heritage, Daejeon, 34122, Republic of Korea

The Dinosaur Egg Fossil Site at Hwaseong Gojeongri in the Republic of Korea (which was discovered while investigating the ecological changes of the tidal mudflats that were revealed after the Sihwa Lake Seawall’s completion) is the first place in Korea where a large number of fossilized dinosaur eggs and egg nests have been found. In particular, it is Korea’s largest dinosaur egg fossil site. Additionally, because it is rare to find so many dinosaur egg fossils in one location, it was designated as the Korean Natural Monument No. 414, in recognition of its natural historic and academic value.