Ya'an Earthquake:1 according to China Earthquake Networks Center, the Ya'an Earthquake occurred at 8:02, April 20, 2013 (Beijing time). The epicenter was located in Lushan County, Ya'an City (30.3N, 103.0E), at a depth of 13 km, and the earthquake had a magnitude of 7.0. As of 10:00, April 24, 2013, there were 4045 aftershocks, with 103 aftershocks above magnitude 3 and the biggest being 5.7. 12,500 square kilometers around the epicenter were affected, involving 1.52 million population. According to the China Earthquake Administration, the earthquake has resulted in 196 people dead, 21 missing and 11,470 injured as of 14:30 (UTC+8h, April 24). Figure 1 shows the location of the earthquake occurred.
Location of Ya'an Earthquake
Sina-Weibo,2 an information sharing and exchange platform that provides entertainment, leisure, and other life services for the public, was released in August 2009. By the end of March 2013, the number of registered Sina-Weibo users had increased to 536 million, with an annual increase rate of 6.6%, and the number of its daily active users increased to 49.8 million, by 7.8% from the end of 2012. Sina-Weibo provides timely updates about the earthquake disasters, where users are free to make searches and queries, government users can post dynamic information about security and rescue and the public can communicate on the platform to express their feelings, such as blessing, sadness, anger, anxiety, etc. It also allows users to propose advice on the action of the government to be taken. Figure 2 shows some Earthquake information from Sina-Weibo.
Earthquake information from Sina-Weibo
There is growing evidence that the public will look for relevant information intensively during a certain period of time after the disaster and from all available sources, irrespective of whether the source is considered authoritative.3,6 As citizens can both access and upload disaster information through such an open communication platform, citizen-driven emergency response is a key part of an effective response to a major disaster.
At present, foreign research on this aspect goes earlier than the domestic. Glaser et al.4 analyzed Twitter data during the 2007 California Wild Fires. Vieweg et al.5 researched on the 2009 Red River Floods and the 2009 Oklahoma Grassfires by means of Twitter data too. Nowadays, Twitter has already been an effective platform for real-time updates. In China, scholars also studied the application of micro-blog in disaster response. Qu et al.6 analyzed people's responses to the 2008 Sichuan Earthquake based on Tianya Forum, and Qu et at.7 analyzed people's responses to the 2010 Yushu Earthquake based on Sina-Weibo.