title: Emergent use of Twitter in the 2011 Tohoku Earthquake.
abstract: BACKGROUND
  Social networks play an important role in disaster situations as they have become a new form of social convergence that provides collective information. The effect of social media on people who experienced disaster should be assessed. Hypothesis In this study, Twitter communication during the Great East Japan Earthquake of March 11, 2011 was assessed. The hypothesis of this study was that usage of Twitter had psychological effects on victims of the disaster.
  
  
  METHODS
  A cross-sectional questionnaire survey was carried out in cooperation with a major Japanese newspaper three months after the disaster, and 1,144 volunteer participants responded. They were asked about their health, area of residence, property damage they had experienced, information sources they used at the time of the disaster, and their usage of Twitter. Further, the Twitter users were divided into two groups-with and without disaster experience. Their psychological effects relating to feelings of relief, stress or anxiety that they experienced in using Twitter were compared between two groups, and Twitter's psychological risk of disaster experience was estimated as an odds ratio.
  
  
  RESULTS
  Twitter users in this study tended to reside in disaster-affected areas and thought Twitter was a credible information source during the time of the disaster. The psychological effect of Twitter differed based on participants' disaster experience and gender. Females with disaster experience reported more feelings of relief and stress as a result of using Twitter compared to females who did not experience the disaster. On the other hand, males with disaster experience only reported more stress experiences as a result of using Twitter compared to those without disaster experience.
  
  
  CONCLUSIONS
  Twitter users with disaster experience had a higher usage of Twitter than those without disaster experience. Social media might have had a material psychological influence on people who experienced disaster, and the effect differed by gender. Regardless of gender, negative feelings were transmitted easily among people who experienced the disaster. It was anticipated that the application of Twitter in a disaster situation will be expanded further by taking these findings into consideration.
authors.affiliation: 1 Department of Education, Hakuoh University, Tochigi, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Umihara
authors.forename: Mariko
authors.initials: M
authors.lastname: Nishikitani
mesh_terms: D000293:Adolescent; D000328:Adult; D057218:Blogging / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D055866:Earthquakes; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D061108:Social Media; D055815:Young Adult