SPECIAL ISSUE PAPER Building knowledge base of urban emergency events based on crowdsourcing of social media Zheng Xu 1,2, * ,† , Hui Zhang 2 , Chuanping Hu 1 , Lin Mei 1 , Junyu Xuan 3 , Kim-Kwang Raymond Choo 5 , Vijayan Sugumaran 6 and Yiwei Zhu 4 1 The Third Research Institute of the Ministry of Public Security, Shanghai, China 2 Tsinghua University, Beijing, China 3 Shanghai University, Shanghai, China 4 Zhejiang Business Technology Institute, Ningbo, China 5 University of South Australia, Adelaide, Australia 6 Oakland University, Rochester, MI,USA SUMMARY An emergency event is an unexceptional event that exceeds the capacity of normal resources and organiza- tion to cope and a situation that poses an immediate risk to health, life, property, or environment. Crowdsourcing connects unobtrusive and ubiquitous sensing technologies, advanced data management and analytics models, and novel visualization methods, to create solutions that improve urban environment, human life quality, and city operation systems. The crowdsourcing on social media can be used to detect and analyze urban emergency events. In this paper, in order to detect and describe the real-time urban emergency event, the knowledge base model is proposed. The crowdsourcing-based knowledge base model is firstly in- troduced, which uses the information from social media. Secondly, the basic definition of the proposed knowledge base model including keywords, patterns, positive sentences, and knowledge graph is given. Thirdly, the temporal information is added to the proposed knowledge base model. The case study on real data sets shows that the proposed algorithm has good performance and high effectiveness in the analysis and detection of emergency events. Copyright © 2016 John Wiley & Sons, Ltd. Received 25 August 2015; Revised 23 December 2015; Accepted 26 December 2015 KEY WORDS: crowdsourcing; emergency events; social media; knowledge base 1. INTRODUCTION An emergency event is an unexceptional event that exceeds the capacity of normal resources and organization to cope and a situation that poses an immediate risk to health, life, property, or environment. Usually as emergency managers, local authorities perform their duties in emergencies to prevent a worsening of the situation, such as the expanding in the region scope, or an increase of the destruction and the loss, or the intensifying of social unrest. The objective conditions, such as the lack of information, timely changeable situation, short time for decision-making, and serious consequences, bring a great challenge for government emergency response. The extraction of accurate information is very important in emergency response. Social media provide a platform for data mining and information extraction. The route of the development of emergent events is extremely complex, one strong initial event may trigger an emergency, which develops in a cascade-like manner and finally has *Correspondence to: Zheng Xu, The Third Research Institute of the Ministry of Public Security, Shanghai, China. † E-mail: xuzheng@shu.edu.cn This paper is the extended version (50% new content) of the conference paper accepted by SKG2015. Copyright © 2016 John Wiley & Sons, Ltd. CONCURRENCY AND COMPUTATION: PRACTICE AND EXPERIENCE Concurrency Computat.: Pract. Exper. (2016) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/cpe.3780