## 2 Research Aims, Materials, and Method
### Methodology
#### 2.2.2 Literature Assessment  
* **Step 1: Data collection and literature assessment of scientific and Grey Literature** The batch of scientific literature was obtained from Scopus(r), an abstract and citation database of peer-reviewed literature acknowledged worldwide, that was also exploited by most of the previous publications listed in Table 1. In order to select the most significant papers, we took into account products by both remote sensing experts that have applied their knowledge to heritage assets and by cultural heritage scholars that have employed remote sensing techniques in their research activities. As far as the batch of Grey literature is concerned, a list of significant titles was built according to our experience and background, with a specific reference to the \"Terminology\" defined for the purposes of this study (see also Appendix A). Hence, Step 1 was further subdivided into Steps 1A and 1B to allow a separate but parallel assessment of the two Batches. * **Step 1A: Indexed literature assessment. (collection, decimation, definition)*
* Collection: As a result of the definition of terminology, several combinations of keywords were applied to the scientific batch to perform the search f articles (see Supplementary Materials: List of scientific articles obtained through Scopus--Step 1A). The focus was placed on archaeological heritage monitored using satellite technologies, while six (6) different terms for damages were employed. The combinations were hence proposed as follows:
* \"satellite\" AND \"heritage\" AND \"archaeology\" AND \"hazard\"
* \"satellite\" AND \"heritage\" AND \"archaeology\" AND \"disaster\"
* \"satellite\" AND \"heritage\" AND \"archaeology\" AND \"threat\"
* \"satellite\" AND \"heritage\" AND \"archaeology\" AND \"risk\"
* \"satellite\" AND \"heritage\" AND \"archaeology\" AND \"damage\"
* \"satellite\" AND \"heritage\" AND \"archaeology\" AND \"destruction\"
* Such combinations produced a total of 1966 relevant articles. Decimation. The first list of papers was initially checked for double results by running an automatic removal of duplicate values (Microsoft Excel@2016 and 2021). This step was followed by a manual check for detecting duplicates missed by the automatic removal of duplicates due to grammar and lexical errors that may have prevented their identification. This process led to an intermediate result of 849 single papers and 1117 duplicates. Definition. To perform \"Attribute definition\" all articles were manually checked for the categories \"Title\", \"Authors Keywords\", \"Index Keyword\", and \"Abstract\". In multiple cases, in order to be certain of the contents, i.e., the technology employed or damage treated, if any, the full text of the papers was consulted. According to this procedure, 412 papers matched the requirements. At the end of the process, all articles were \"tagged\" for (1) type of heritage studied; (2) type of damage or damages studied in the illustrated case study; and (3) type of technology or technologies employed for damage assessment and monitoring. Through this process, 102 papers were found to be not relevant for this survey, while 15 works were not in any way accessible to the authors, so they were not evaluated. The total number of articles selected for the evaluation of statistics amounts to 295. * **Step 1B: \"Grey\" literature assessment (collection, decimation, definition)*
* Collection: Unlike the indexed literature, there were neither national nor international repositories or catalogues to browse that provided access to the whole body of documents that heritage organizations and institutions or practitioners have produced on the studied subject. This is intrinsic to the definition of \"Grey Literature\" (see Section 2.2). The main categories of documents that were searched for included guidance documents, standards, recommendations, organization/institutional documents, national plans, management plans, technical reports, and non-indexed conference proceedings.