[Expression of negative emotional responses to the 2011 Great East Japan Earthquake: Analysis of big data from social media].

In this article, we investigated the expression of emotional responses to the 2011 Great East Japan Earthquake by analyzing the frequency of negative emotional terms in tweets posted on Twitter, one of the most popular social media platforms. We focused on differences in time-series variations and diurnal changes between two kinds of disasters: natural disasters (earthquakes and tsunamis) and nuclear accidents. The number of tweets containing negative emotional responses increased sharply shortly after the first huge earthquake and decreased over time, whereas tweets about nuclear accidents showed no correlation with elapsed time. Expressions of anxiety about natural disasters had a circadian rhythm, with a peak at midnight, whereas expressions of anger about the nuclear accident were highly sensitive to critical events related to the accident. These findings were discussed in terms of similarities and differences compared to earlier studies on emotional responses in social media.

[Relationship among weblog authors' target audience, contents, and types of interpersonal communication].

Weblogs are one of the most popular personal websites in Japan, where entries are made in journal style and displayed in reverse chronological order. This study examined the relationship between weblog authors' target audience (i.e., orientation) and the actual situations depicted in their weblogs by combining a questionnaire survey of the authors with an analysis of their weblog content data. Based on a questionnaire survey of 736 Japanese weblog authors, their target audience was divided into four clusters: (a) general public, (b) self, (c) self and offline friends, and (d) various others. To assess the actual situations depicted in their weblogs, the amount of happy and unhappy emotional expression in their writing and the frequency of interpersonal communication (comments, bookmarks, and trackbacks) were calculated from their log data. The results suggested that weblog authors wrote different types of content and used different types of communication depending on their audience, whereas the weblog content itself still showed the diary-like characteristic of personal daily-life records.