Delhi blast: What explosive materials were used, and how powerful was it?

Among over 40 pieces of evidence collected by the Forensic Science Laboratory (FSL) team from the Red Fort blast site were two cartridges, one of which was live, along with samples of two different types of explosives, according to a PTI report.

A powerful explosion struck a slow-moving vehicle near the Red Fort traffic signal in New Delhi on Monday, resulting in 12 fatalities.

Initial findings suggested that one sample was ammonium nitrate, a chemical commonly used in fertilisers but known to act as an oxidiser in explosives when combined with other substances. The second sample was reportedly more potent than ammonium nitrate, with its exact composition to be confirmed after thorough forensic analysis, PTI stated.

Let’s explore the types of explosives involved in the Delhi blast and their destructive power.

What are explosives, and how do they function?

Explosives are substances that release a large amount of energy rapidly, producing heat, gas, and a strong shock wave. They are classified based on their strength:

Low explosives: Burn quickly and create pressure (such as gunpowder), causing minor damage

High explosives: Detonate, producing a powerful, fast-moving shock wave that causes extensive damage.

Typically, an explosive contains two main components: a fuel that reacts or burns, and an oxidiser, a chemical that supplies oxygen to accelerate the reaction. The interaction of these results in an explosion.

Ammonium nitrate: Common but hazardous

Ammonium nitrate is a white crystalline substance primarily used as a fertiliser in agriculture. It is generally stable on its own, but when combined with fuel or subjected to intense heat or pressure, it becomes highly explosive. Due to this danger, its storage and use are strictly regulated in India and worldwide.

The Times of India reported that Jammu and Kashmir Police and Haryana Police on Monday seized a large stockpile of 2,900 kg of explosive materials, including 360 kg of ammonium nitrate, from an apartment in Faridabad suspected to be connected to the Delhi blast network.

RDX, PETN: What are they?

Investigators have also requested forensic teams to test for the presence of PETN, Semtex, or RDX, as well as detonator components, according to media sources.

RDX (Royal Demolition Explosive): Chemically known as hexahydro-1,3,5-trinitro-1,3,5-triazine, RDX is a white powder that is highly explosive. It is used alone or combined with other substances in explosives. It is a synthetic chemical not found naturally in the environment.

PETN (Pentaerythritol Tetranitrate): Part of the organic nitrates group, PETN is mainly used for demolition explosives and to manufacture detonating fuses and blasting caps.

Both RDX and PETN are significantly more powerful than ammonium nitrate and are heavily regulated due to their potential for destruction.

What is a detonator?

A detonator is an initiator that triggers the explosion of a main charge such as RDX or ammonium nitrate. It is a small explosive device that produces a rapid spark, heat, or shock sufficient to ignite the main explosive. Detonators function like matches lighting a firecracker.

In the Red Fort incident, detonators and wires recovered from Faridabad indicate the presence of a complete improvised explosive device (IED) setup.

What is a cartridge?

The FSL team also found two cartridges at the blast site. A cartridge is a complete ammunition round consisting of a bullet, casing, and propellant. This suggests possible firearm involvement at the scene, though authorities have not confirmed their use in the blast.

All collected samples are undergoing forensic testing to determine the exact chemical composition, origin, and triggering mechanism of the explosives used.