Paul Rega at Project Disaster has posted a primer on IEDs – anyone and everyone involved in emergency response – especially those who are not in law enforcement or the military – if you know nothing about explosives, know this much:

Improvised explosive devices, or IEDs, are booby traps–disguised or hidden devices–activated by victims or detonated remotely or on command. IEDs have been used since World War II and more recently in Chechnya, Lebanon, Afghanistan, and Iraq.

IEDs are intended to incapacitate or kill and to create intimidation and terror. They are used in unconventional warfare and by definition can be made with almost any type of material and initiator. These “homemade” devices employ pyrotechnic or incendiary chemicals and can be made in combination with toxic chemicals, biological toxins, or radiological material. Although IEDs can be found in varying sizes, functioning methods, containers, and delivery methods, they share a common set of components: some type of explosive fill, an initiation mechanism, a detonator, a power supply for the detonator, and a container. Although the press sometimes refers to them as roadside bombs, IEDs can be in packages, carried in vehicles (“car bombs”), or worn by suicide bombers.

Two or more IEDs may be detonated by coupling, linking one mine or explosive to another so that when one is detonated, the other goes off; rolling, setting off an unfuzed explosive after a mine-clearing roller has passed over it, by means of a second, fuzed device, which detonates the first one when it is underneath the clearing vehicle; boosting, stacking buried mines atop one another, with the deepest device being fuzed, helping reduce metal detection and increasing the force of the blast; sensitizing antitank mines, removing the pressure plate or spring to reduce the pressure required to set them off; and daisy chaining, linking mines to other explosives with trip wire or detonating cord.

IED configuration affects the velocity of explosion and the type of damage: low explosives must burn in a confined space so that the gas formed causes an explosion; high explosives generally must be detonated by a shock wave of considerable force, usually from a detonator or blasting cap.

To detect a victim-activated IED requires recognition of the initiating object as a booby trap. The enemy wants the unwary or distracted person to interfere with the object to set it off by touching or picking it up. IEDs have been found in tires, garbage bags, fire extinguishers, barrels, and dead animals.

Threat indicators include the theft of explosives or of chemicals used in making explosives; the rental of self-storage space to store explosive apparatus; deliveries of chemicals to residences; the purchase, rental, or theft of a large van or truck; or the addition of heavy-duty springs to a large vehicle to handle heavier loads.

Technologies are being developed to access, diagnose, and defeat terrorist IEDs by locating and identifying bomb components, increasing standoff capabilities, reducing collateral damage, and improving robotic systems for remotely disabling explosives.

Potentially hard targets such as government facilities, military bases, and airports as well as soft targets such as public buildings need to be protected. Metal detectors, x-ray screening, and explosive trace detectors can be employed at hard targets, but even soft targets can be protected by a physical security plan to prevent or control access and a bomb incident plan. Police departments, fire departments, and local government agencies can help in developing a plan. The most important aspect of a bomb incident plan is a chain of command that outlines the responsibilities of each member of the chain. Regular drills identify weaknesses so that they can be corrected and so that practice makes everyone aware of procedure. Awareness training can help people become aware of odd behavior by people who are looking to cause harm. Signs informing people how to report suspicious activity can also help.

In an actual IED attack, it is vital to leave the scene immediately, moving to an open space or protected area, because there could be a secondary explosion. Avoid forming a crowd, and avoid tall buildings, glass windows, vehicles, and rubbish bins. Upon reaching a secure area, call 911 if authorities have not yet arrived. If there are already officers at the scene, follow their instructions so that the scene can be secured and safety maximized. Remain aware and report any suspicious individuals, activities, vehicles, or objects.

Sources of Information

GlobalSecurity.org
Improvised Explosive Devices (IEDs) / Booby TrapsWikipedia
Improvised Explosive Device descriptions and history

Technical Support Working Group
Improvised Device Defeat

Emergency.com
Potential Indicators

Security Driver
Explosive Forces of IEDs

Airport International
Protecting People and Facilities From IEDs

Hats off to Paul and his colleagues at Project Disaster for another post that explains complex and important issues to non-specialists.