“Contents under pressure may explode” has never been more accurate. Pressure cookers heat food with steam, using increased internal atmospheric pressure to heat and trap steam beyond its normal limit of 212 degrees Fahrenheit. This same increase in temperature is exploited by a pressure cooker bomb to amplify the power of an explosion set off within.
A pressure cooker bomb, like the one used in Boston [and New York City in Sept 2016], takes the rapidly-expanding gasses in a typical gunpowder explosion and holds them under tighter atmospheric pressure. The resulting rupture is far more violent than if the gunpowder was placed in a non-pressurized container.
So where did the idea come from? It’s hard to nail down. A report published by the Department of Homeland Security in 2004 describes pressure cooker bombs used by various rebels and militant groups in both India and Algeria; a later DHS report from 2010 mentions pressure cooker bombs used in Afghanistan, Nepal, and Pakistan, as well as an attempted use in Times Square.
Recent reporting on pressure cooker explosives tied to the Boston Marathon bombing note that al Qaeda’s English-language magazine “Inspire” includes a pressure cooker bomb recipe, but the design predates the existence of al Qaeda by decades. The Anarchist Cookbook, an infamous manual known for its explosives instructions, discussed the explosive potential of pressure cooker bombs back in 1971.
Pressure cooker bombs have a long history and a diverse list of users. In India, they’ve been used by Maoists, as well as terror groups involved in Kashmir. In France back in 2000, an Algerian terror group attempted to use pressure cooker bombs. In Greece this past January, a pressure cooker explosion was attributed to anarchists. The materials used to make pressure cooker bombs are neither expensive nor unique, and the instructions are widely available. Claiming that “pressure cooker bombs are a signature attack” of any specific group is about as ridiculous as claiming “bullets are uniquely used by American soldiers.”
In understanding and investigating the aftermath of the attacks, answers are going to be found everywhere but the nature of the bomb.
The above infographic, the first part of a four-parter over at USA Today, shows visually how these bombs work as well as possible prevention tactics. It’s worth a look, for sure.