## 1 Introduction  
Major disasters pose global challenges [1] around the world not only because they typically affect large areas and can have impacts that cross national borders, but also because they typically incur considerable damages to residents, societies, and economic systems. Some disasters even require international assistance for the emergency response and relief. Annually, roughly 300 major disasters are recorded under the Centre for Research on the Epidemiology of Disasters (CRED) through its Emergency Events Database (EM-DAT) [2]. Timely and accurate assessments of damage are critical to better understand the overall impacts of disasters and to support more scientific decision making that can guide emergency rescue, relief, and reconstruction efforts. Global open geo-information and other information drawn from multiple sources, including formats of different levels and scales based on appropriate integration approaches, could not only be used to estimate the extent of damage involved, but also to observe spatial and temporal patterns for disaster damage assessments that support disaster management in instructive and effective ways [3]. Disaster assessments involve the use of dynamic processes determined based on different emergency stages, accessible data sources, and outcome accuracies, and can be divided into three types: rapid impact estimations, physical damage assessments, and comprehensive assessments. As more time passes after a disaster occurs, more sourced and detailed data can be accessed for damage assessments, thus rendering the results more accurate. Rapid impact estimations are typically conducted within hours to days following a disaster and are based on experimental approaches (e.g., the Prompt Assessment of Global Earthquake for Response (PAGER) system [4] developed by the U.S. Geological Survey and the Global Disaster Alert and Coordination System (GDACS)) [5] that can be used to initially determine the possible impacts for disaster managers. Comprehensive disaster assessments are conducted based on thorough and detailed datasets using multiple approaches, including ground surveys, when disaster conditions are stable and when emergency response operations are ending, which can sometimes occur after several months [6, 7], in turn producing accurate and thorough outcomes for further recovery and reconstruction planning. Periods of time ranging from hours to weeks or months are required for disaster rescue and emergency relief efforts when physical damage assessments are required. Populations, buildings, infrastructure, and other physical assets are the main affected elements that are assessed after a disaster. As there is typically a lack of complete post disaster information due to time limitations, physical damage assessments are conducted by integrating as much available information as possible. Satellite remote sensing methods integrated with other geo-information tools are widely used for physical damage assessments. As disaster conditions are changing at this stage, damage assessment information requirements for supporting disaster response measures are also dynamic and urgent. As more data become available with the passage of time after a disaster occurs, the accuracy and covered area of a physical damage assessment also improves. With the development of advanced geo-information technologies and with the promotion of global open data, enormous global open geo-datasets are now accessible and could be utilized for dynamic disaster assessments when integrated with other information. Although global open source datasets are typically available at a coarser scale relative to local scale geo-datasets, they are suitable for efficient and large-scale damage estimations as they are created in standard formats and are easily accessible. The existing global dataset with information on elements for disaster assessment includes hazard, exposure, post-disaster, and auxiliary data.