Washington, Dec 14 (IANS): A study that analysed emotional reactions on Twitter in 95 cities worldwide following the 2013 Boston Marathon bombing, may help governmental agencies in understanding how to best handle public fear after a terrorist attack.

In a first large-scale analysis of fear and social support reactions from geographically distant communities after a terror attack, researchers from the University of Pittsburgh and Cornell University analysed emotional reactions on the micro-blogging site in the hours and weeks following the attack.

The findings show the extent to which communities outside Boston expressed their emotions by using hashtags such as #PrayForBoston and how those reactions correlated with geographic proximity, social network connections and direct ties to Boston.

"The findings of our study will potentially assist officials in predicting the exact manner and extent in which citizens in their own regions will react to tragic occurrences in another region of the country, said principal researcher Yu-Ru Lin, an assistant professor in Pitt's School of Information Sciences, US.

For the study, researchers analysed over 180 million geo-coded tweets from individuals in 95 cities around the world.

Researchers focused their analysis on the 60 most-populated metropolitan areas in the US as well as the 35 highest-populated cities outside the US.

The study also utilised Twitter hashtags to identify tweets reflecting expressions of solidarity and sympathy.

Researchers found that citizens in some cities were more likely to express specific emotions based on geography and shared experiences.

The hashtag #PrayForBoston was used to identify expressions of sympathy.

Citizens in London were modest in their expressions of fear and solidarity but were more forthcoming in their use of the #PrayForBoston hashtag, the team noted.

The hashtag #BostonStrong was used to measure expressions of solidarity that were used most by citizens in the US cities that possess geographic proximity and have similar cultural identities as Boston.

"The immediate emotional reactions on social media are indicators of deeper feelings of connection to suffering in other communities that linger," said Drew Margolin, an assistant professor of communication at the Cornell University, US.

The paper is available online in the journal EPJ Data Science.