Looking back a year later, we can see six key lessons about leadership in the way the Boston Marathon bombings were handled.

Almost a year has passed since two bombs fashioned from pressure cookers detonated at the finish line of the Boston Marathon, killing three people and injuring over 260. The alleged assailants also were implicated in the murder of an MIT police officer several days after the initial attack.

Nothing about the awful afternoon of the Marathon is more compelling than the stories of human tragedy and heroism that accompanied it. But alongside those stories is also a story of a transformed landscape of crisis communications — one overtaken by social media, moving at light speed and driven by the citizen activist rather than the C-suite. The dominant communications vehicles in the hours and days following the attack were neither the press release nor the press conference; they were instead the Twitter feed and the text message.

Therein lie lessons for leaders and corporate communicators for whom, unfortunately, crises are an increasingly common phenomenon. Most say that they are prepared for crises, yet few are truly prepared for the media intensity that follows — an observation made by former British Petroleum CEO Tony Hayward about his company’s readiness for the 2010 oil spill in the Gulf. As Hayward told the BBC, the lack of a robust contingency plan had the company “making it up day to day” in the full glare of the media spotlight.

Disaster sociologist Jeannette Sutton, who is a principal investigator at the HEROIC project (an acronym for Hazards, Emergency Response and Online Informal Communication), studied the impact of Twitter before and after the Marathon bombings. After reviewing what Sutton learned from tracking 31 officials and civic authorities, we’ve distilled six lessons for corporate leaders for both preparing for and reacting to a crisis:

Keep in mind that your stakeholders are, well, everyone.

Leaders are accustomed to identifying key stakeholders and communicating with them in terms they can understand. Technology has enabled them to segment those audiences into ever smaller ones micro-targeted with ever more precise messages. A corporate communications officer once told me that he only had to worry about 50 decision makers in total. In this new world, social media has amalgamated those subdivided audiences back into one undifferentiated crowd.

Communications via text and Twitter aren’t confined to audiences you select. They’re open to anyone who subscribes, or anyone who listens to someone who subscribes.

Discipline yourself to shorter messages before a character limit does it for you.

According to researchers at IBM Research Labs in Delhi, India, nearly 8 million Tweets were made by 3.7 million unique Twitter users in the five days after the Boston bombing. This is a great amount of information. In the blizzard of messages, shorter is better.

In preparing for a crisis, leaders need to be trained to write in simple and compelling terms that are Twitter-worthy. In our Firebell™ crisis simulation training for clients, we often ask leaders to communicate messages in 140 characters — the Twitter maximum — to succinctly convey what the public might need to know right away. Writing short is harder than you think.

Twitter isn’t meant to convey every detail. It’s a push-pull vehicle that’s useful for directing a reader to other sources. Companies need to be prepared to point followers to longer-form information on a website or Facebook page for more information.

Pick a single hashtag to use on Twitter posts.

On Twitter, a hashtag is the perfect notification/response system. It enables diverse audiences to receive information, spread information and respond or act.

This did not happen in Boston. After the Marathon explosions, information was delivered from officials with no fewer than a dozen hashtags, from #NotifyBoston to #alertBoston. This splintered information and made communications harder. Compare this to the protests in Ukraine, in which the widespread use of the single hashtag #euromaidan, named after the square where protests were taking place, surfaced almost immediately.

Accept that no single entity owns the information environment.

Massachusetts General Hospital first heard about the bombings not from emergency response authorities, but from reports ricocheting around Twitter that an ER doctor picked up. Lives were saved as a result: The hospital held back on less urgent surgeries and kept operating rooms available for bombing victims.

It’s an illustration of how the information environment is no longer owned from the top down. Accepting that neither your company nor any “official” voice owns the information environment can be empowering: it can prompt leaders to embrace the need for readiness and to recognize situations in which they need to double-time their way back in front of a story.

Don’t be afraid to show some emotion.

Following the Bombing

View Exhibit

This chart shows how Twitter followers of different officials rose as events unfolded in the hours and days after the Boston Marathon bombings on April 15, 2013, and how followers continued post-event. Source: HEROIC Project, Following the Bombing.

People need information in a crisis, but sometimes they need emotion and empathy, too. They provide reassurance, connection and a sense of common purpose that can pull disparate audiences together.

The day after the bombing, for instance, Boston Mayor Tom Menino tweeted: “We are a strong city. We will pull together as neighbors.” Similarly, the Boston Police Department, after arresting the suspect whose flight put the city on lockdown three days later, tweeted “CAPTURED!!! The hunt is over. The search is done. The terror is over. And justice has won. Suspect in custody.” With these messages, the Mayor and the Police Department both avoided one of the biggest mistakes leaders and corporate communicators tend to make, which is to focus on distributing information at the expense of emotional engagement

Keep communicating post-crisis.

Don’t jolt people who follow you during a crisis by suddenly switching to a new topic after the crisis peaks. Particularly in tragic situations, it’s important to respect the mourning process. The chart “Following the Bombing” shows how the Boston Police retained their Twitter following even weeks after the final suspect was arrested. Good crisis communication presents an opportunity to build an enduring relationship with audiences.

The era of social media is only a decade old, but already it has seized control of the leadership communications landscape. As with most realities, the question is not whether leaders accept this one, but whether leaders embrace it.

Social media offers opportunities: the Boston Police Department’s relationship with its constituents is stronger today than it was before the Marathon bombings, as are the relationships with other official organizations that took the lead that week. Crises can work that way. But those opportunities must begin with recognition that the landscape we confront today is vastly different than the one we faced a decade ago.

The Marathon bombings showed us many things, including humanity at its worst — and its finest. Let’s make sure we learn our lessons well.