Tweeting What Matters: Information, Advisories, and Alerts Following the Boston Marathon Events

This is the third report by the HEROIC project team on the use of Twitter by official accounts responding to events in Boston during the week of April 15-19, 2013.  In our previous reports [Sutton et al.; Sutton et al.], we provided background on Twitter use during the bombing event, the initial findings related to allocation of attention by members of the public to official accounts, and the use of relational and conversational features that may have been included as part of posted tweets.  In this final report, we focus on the aspects of message content with special attention to public guidance to those placed on lockdown, discussing the role of Twitter as a redundant channel for risk communications.

We first focus on the content of the Tweets over the five day period.  Tweet content falls into one or more of 10 categories identified by the research team and includes such things as “advisories” (telling people about specific actions they should take that may or may not lead to personal protection), “closures or openings” (of streets, public transportation, services or events), “hazard impact” (injuries, deaths, resources used in response to the event), “information” (help lines, tip lines, preparedness suggestions, resources and fact sheets), and “volunteer/donate” (donate or volunteer in response to the event).  We also include categories for “off topic” tweets that are posted by one of our selected organizational accounts, but not relevant to the hazard event of study and “unknown” tweets that do not include enough information to detect the topic.

We begin by looking at the content streams grouped by organizational sector.   In Figure 1 below, we see that information themed tweets were by and far the most common tweets throughout the week, and that law enforcement, crisis response, and government/elected officials contributed the most tweets to this area.  Closures and openings are the second most common tweet and comprise information about roads and public transportation.  Not surprisingly, the transportation sector contributed most heavily to this content stream, led by the Massachusetts Bay Transportation Authority (@mbtaGM) and Boston Logan airport (@bostonlogan).  The next most highly tweeted theme is advisory tweets. At the beginning of the week, advisory tweets focused on clearing the area near the bombing and strategies to locate loved ones; at the end of the week, advisory tweets focused on actions to take while the city was on lockdown.  Advisory tweets were posted primarily by law enforcement.

Off topic tweets were also consistently seen among our selected accounts.  This occurs for two reasons. First, not all of the organizations that we chose for this analysis have disaster response as a primary mission. This includes the regional office of the National Weather Service, which tweeted consistently throughout the event, but not about the marathon response or manhunt. Second,  many of these organizations continued to conduct their daily operations as the weeklong events unfolded, providing both event-related tweets as well as tweets relevant to their normal daily activity.

At the mid range of the graph are tweets that include words of thanks or emotive content about the heroism of the first responders, condolences for those who died, and encouragement for Boston Community to stay strong.  Sectors tweeting about these themes include crisis response, law enforcement, and government and elected officials.  The least tweeted theme is direct messages responding to requests for help, where there is a clear indication that Twitter is being used as a conversational tool rather than purely for broadcast.  During the Boston response, few organizations used Twitter as a backchannel, direct messaging tool.

Figure 1.  Tweet volume across thematic content areas, grouped by organizational sector.

Evacuation and shelter-in-place tweets are a variant of advisory messages that provide specific guidance about how to protect oneself in disaster.  While we did not observe a high volume of tweets in this content area, we take note of it because of its function in this specific event.  At the beginning of the week, following the detonation of the IEDs, few guidance-related tweets were posted, possibly signifying the lack of certainty about the event, the speed at which it unfolded, and having little information regarding what people should do in response.  However, at the end of the week, guidance tweets were became more prevalent and focused on sheltering in place. Shelter in place tweets came from two organizational sectors, law enforcement and government/elected officials at both the local and the state level.  Importantly,  Twitter was only one channel among many to relay protective action guidance in the midst of the lockdown.  Analysis of the public tweet stream, in particular messages  which included the key words “emergency alert,” revealed that warning messages were disseminated via text, email, landline, and mobile devices and included opt-in services, downloaded apps, and the Wireless Emergency Alert system via mobile carriers.

At least eight universities utilized their campus-based alert systems (these included MIT, Harvard, Boston University, Emerson College, Quincy College, Tufts University, Mt Ida College, and Simmons College).  In addition, the City of Boston utilized “Alert Boston”, Cambridge, MA used the CodeRed mobile phone app and Massachusetts Emergency Management Agency disseminated alerts via the “ping4alerts” mobile phone app. All three of these systems required constituents to opt in.  In addition, Massachusetts Emergency Management Agency utilized the Wireless Emergency Alert system to send messages to WEA-enabled mobile devices, advising residents to remain sheltered in place.

Figure 2.  Wireless Emergency Alert message sent by MEMA.

The activation, timing, and frequency of various alerts over the course of April 19 likely played a role in the retweeting of guidance messages.   Push-messaging systems that delivered alerts directly to individuals may have influenced the high volume of retweets in the early morning hours from 2:00 am on.  However, messages about the shelter-in-place orders were overshadowed by other tweets throughout the day, (by comparison of retweet volume for individual messages) as information was released about the suspect,  requests were made to protect information on officer tactical positions, and condolences were offered for the death of Officer Collier who was killed by the suspects on the previous night.  Differences in the level of retweets for these specific themes may be related to perceptions about information relevancy; if friends and neighbors have already been directly warned by an alerting system, multiple times, through many different channels, is there value in re-posting shelter in place orders? In contrast, information about the suspects may be perceived as relevant for those who wanted to contribute to the resolution of the investigation or for persons with a general interest as events unfolded.

There is clear evidence that Twitter was utilized as a redundant channel to provide shelter in place alerts and regular updates throughout the day.  This was coupled with messages delivered through other push-messaging systems, intended for individuals who were considered to be most at risk.  However, analysis of the retweets of various content themes indicates that for this particular event information about the suspects, the response, and the hazard impact may have had greater relevancy to a broader population that was observing the unfolding events from both near and far away.  Such findings reflect both the level of attention throughout the week as well as the kinds of messages relevant to different audiences and the redundancy of local communications.  With this in mind, it is becoming prudent for organizations to consider the kinds of information that is most desired by an online audience, at different points in time, and for different sectors of the public.  Messages can be crafted for both locally affected community members in need of advisories and guidance, as well as distant observers intent on serving as information conduits.  Future disaster communicators ought to learn from these detailed observations about public retweeting practices in order to determine how to more effectively focus, shape, and share messages that make a difference.


Sutton, J., Johnson, B.,  Spiro, E.,  and Butts, C. (2013). “Tweeting What Matters: Information, Advisories, and Alerts Following the Boston Marathon Events.” Online Research Highlight.



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