Ya'an Earthquake: 1 according to the 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, 4045 aftershocks occurred, among which 103 were above magnitude 3, with the biggest being 5.7. An area of 12500 km2 around the epicenter was affected, involving 1.52 million people. According to the China Earthquake Administration, the earthquake caused 196 people dead, 21 missing and 11470 injured as of 14:30, April 24. Figure 1 shows the location of earthquake occurrence.
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 launched in August 2009. By the end of March 2013, Sina-Weibo had a number of 536 million registered users, with an annual increase rate of 6.6%, and the number of its daily active users increased to 49.8 million, by 7.8% as of the end of 2012. Sina-Weibo provides timely updates about earthquake disasters. It is a platform where users are free to make searches and queries, where government bodies can post dynamic information about security and rescue, where the public can communicate to express their feelings, such as blessing, sadness, anger, anxiety, etc., and where users can propose to the government actions to be taken. Figure 2 shows some earthquake information at Sina-Weibo.
Earthquake information obtained from Sina-Weibo
There is growing evidence8–11 that the public would look for disaster information most intensively during a certain period of time after its occurrence, irrespective of the sources.3,6 As citizens can both access and post disaster information at open social platforms, such information constitutes a key part of effective responses to a major disaster.
On this aspect, research abroad goes earlier than the domestic. Glaser et al.4 analyzed Twitter data during the 2007 California Wildfires. Vieweg et al.5 researched on Twitter data for the 2009 Red River Floods and the 2009 Oklahoma Grassfires. It can be seen that Twitter has already been an effective channel for real-time updates. In China, scholars also studied the application of microblogs in formulating disaster response. Qu et al.6 analyzed people's responses to the 2008 Sichuan Earthquake based on Tianya Forum data, and Qu et at.7 analyzed people's responses to the 2010 Yushu Earthquake based on Sina-Weibo microblogs.