Did the Bomber Time the Blasts to Maximize Casualties?

Your News Companion by Ben Mathis-Lilley
April 16 2013 3:33 PM

Did the Boston Marathon Bomber Time the Explosions to Guarantee the Most Possible Casualties?

The first of two bombs that exploded at the Boston Marathon yesterday went off with 4:09:43 on the clock at the finish line, with the second following shortly thereafter. That timing raises suspicion that the bomber wanted the blast to happen when an exceptionally high volume of people would be massed near the finish line.

In the graph above, each blue bar represents a minute of completion time in the 2012 Boston Marathon—the last race where we have complete data—and the height of each bar represents the number of people who finished in that minute. As it shows, the most common completion times surround the four-hour mark.


Boston Marathon runners are divided into waves, with the vast majority starting in Wave 1 (at 10:00 a.m. EDT), Wave 2 (at 10:20) and Wave 3 (at 10:40). It’s worth noting that, since there are 9,000 runners in each of these three waves, not every runner begins the race at exactly those times—there can be delays of several minutes, if not more, before runners make it through the pack and reach the starting line. The red line in the graph reflects the time elapsed from the moment the first group of Wave 3 runners started the race and the instant the first bomb went off. As it shows, the bombs exploded as many Wave 3 runners finished around 4:10 and as runners who started further back in the wave reached other times close to the median—4:09, 4:08, 4:07, etc.

The bombs also hit as Wave 2 runners, who had started 20 minutes before Wave 3, completed the race around the 4:30 mark and Wave 1 runners, who started 40 minutes before, completed it in around 4:50.

In other words, the bombs went off as the traffic crossing the finish line—and presumably the volume of spectators watching their family members and friends finish—would be near its peak.

Heather Brady contributed to this report.



More Than Scottish Pride

Scotland’s referendum isn’t about nationalism. It’s about a system that failed, and a new generation looking to take a chance on itself. 

What Charles Barkley Gets Wrong About Corporal Punishment and Black Culture

Why Greenland’s “Dark Snow” Should Worry You

Three Talented Actresses in Three Terrible New Shows

Why Do Some People See the Virgin Mary in Grilled Cheese?

The science that explains the human need to find meaning in coincidences.


Happy Constitution Day!

Too bad it’s almost certainly unconstitutional.

Is It Worth Paying Full Price for the iPhone 6 to Keep Your Unlimited Data Plan? We Crunch the Numbers.

What to Do if You Literally Get a Bug in Your Ear

  News & Politics
Sept. 17 2014 8:15 AM Ted Cruz Will Not Join a Protest of "The Death of Klinghoffer" After All
Sept. 16 2014 4:16 PM The iPhone 6 Marks a Fresh Chance for Wireless Carriers to Kill Your Unlimited Data
The Eye
Sept. 16 2014 12:20 PM These Outdoor Cat Shelters Have More Style Than the Average Home
  Double X
The XX Factor
Sept. 15 2014 3:31 PM My Year As an Abortion Doula
  Slate Plus
Slate Plus Video
Sept. 16 2014 2:06 PM A Farewell From Emily Bazelon The former senior editor talks about her very first Slate pitch and says goodbye to the magazine.
Brow Beat
Sept. 16 2014 8:43 PM This 17-Minute Tribute to David Fincher Is the Perfect Preparation for Gone Girl
Future Tense
Sept. 16 2014 6:40 PM This iPhone 6 Feature Will Change Weather Forecasting
  Health & Science
Bad Astronomy
Sept. 17 2014 7:30 AM Ring Around the Rainbow
Sports Nut
Sept. 15 2014 9:05 PM Giving Up on Goodell How the NFL lost the trust of its most loyal reporters.