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According to the observation, almost all of the 77 cracks should be developed from the stone interlayers. The depth of 15 cracks has been detected and the results are between 0–68 mm. By USCT, a loosened zone with thickness up to 50 mm has also been found.

Table 2: Crack depth data.

For the reason of the statue has just been exposed to the natural environment for only 35 years, the marble should be in the early stage of deterioration, that is surface crystal fabric loosing and surface cracks developing.

The main factors that cause crystal fabric loose on marble surface, development of spalls and cracks should be sharp drop in temperature caused by sudden rain in summer, repeated uneven expansion and contraction, scouring and dissolution of 178acid rain, ice splitting action and growth of lower organisms such as mosses and lichens, etc.

If no effective measures are taken, the deterioration level of the statue may increase quickly, perhaps even seriously in the next 50 years producing a similar state as the marble railing of Tian’anmen-Qing Dynasty monument (Fig. 10).

Figure 7 : Laboratory samples and corresponding USCT images. a. Ø 22 cm wood sample and corresponding USCT image. b. Ø 28 cm wood sample and corresponding USCT image. c. Ø 22 cm wood sample and the corresponding USCT image. d. Ø 55 cm limestone sample and corresponding USCT image.

Figure 8: USCT testing section.

Figure 9: USCT testing. a. USCT testing array b. USCT image

Figure 10: Lack of effective protection leads to serious deterioration. a. Head of the Statue b. Marble railing of Qing Dynasty monument

It is absolutely necessary to fill cracks and crystal gaps with suitable materials to slow down the deterioration process. We also suggest physical protecting methods be taken to prevent the statue from the weathering factors as sudden rain, sun light, ice and acid rain, etc.