Explosives Flashcards Preview

Trace Evidence > Explosives > Flashcards

Flashcards in Explosives Deck (27):

Initial response for explosion incident is:

- Gain control of the scene
Preservation of life and treatment of casualties first priority
Identify victims
Important to have forensic awareness training


Post explosion incident scene control:

- Gain control of scene
- Place cordon around scene, radius of 100-200m
- Point of explosion would be the center point
- Radius will depend on debris field and environment


Purpose of Cordon is:

- Preserve the scene
- Allows systematic and effective recovery of evidence
- Control access and movement
- Allow forensic recovery to happen in undisturbed and safe way


Goals for recovery after explosive incident is:

- Determine cause of explosion
- Construction, components and functioning of explosive device
- Nature of explosive charge
- Recover physical and chemical evidence


Place recovered items from explosion in airtight nylon bag:

- Time and date of recovery
- Recovery location
- ID of person recovering evidence
- Unique identifier
- Log item out of scene


Two essential components of explosive device:

- Explosive charge
- Means to initiate charge


Parts of explosive device may include:

- Explosive train/ various explosives to achieve detonation
- Electrical components/ wires, batteries, leds
- Timing devices
- Shrapnel/ nails and screws
- Sensors/ proximity and movement
- Switches/ mechanical and electronic


Types of explosions:

- Mechanical/ buildup of pressure until vessel fails
- Chemical/ chemical reaction from heat, light gases
- Nuclear/ splitting or fusing of atoms; energy from heat and X-rays
- Electrical/ high energy arcs that generate heat for explosion;energy of
reaction energizes atoms of target material until breakdown occur
Ex: lighting, short circuit


Primary effect of explosion:

- Blast wave (pressure)
- Fragmentation
- Incendiary (thermal component)


Blast wave is:

- Pressure wave that radiates outward from point of explosion
- May be produced by expanding gases and combustion
- Causes the most damage
- Radiates outward rapidly; distance increases, speed and pressure drop
- At point of explosion, vacuum created air is pushed away by pressure


Fragmentation is:

- Device broken into pieces by blast or when objects are attached
to the outside or included inside a device to increase blast
damage to kill and injure personnel
- Common in IEDs and hand grenades
- Low explosives (cause large rectangular shaped fragments)
- High explosives ( cause small triangular shaped fragments)


Fragmentation types are:

- Primary (shrapnel or fragments from initial explosion)
- Device casing or objects attached to outside

Secondary (when primary fragments stroke something and impart directional energy to that object)


Primary effect of explosion:

Incendiary Thermal Effect
- High temperature from explosion
- Maybe localized at point of explosion
- Can be done remotely from hot fragments hurled outward from point of explosion
- Most incendiary explosions will cause incendiary effect of some type


Improvised Explosive Device (IED) consist of:

- Detonator
- Booster
- Main Charge


Elements of IEDs:

- Explosive
- Initiation System
- Container
- Binding material
- Shrapnel and other hazardous material


IED components are:

- Switch
- Initiator
- Explosive
- Power source


Essential components of explosive device:

- Explosive charge
- Means of initiating charge

* Post explosion; basis of forensic recovery.


Four major elements of explosion:

- Rapid increase in gas pressure
- Confinement of pressure
- Rapid release of that pressure
- Damage or change to the confining structure of the vessel


Post explosion recovery:

- High explosive (shattering ability, damage such as irregular fracture provide evidence of detonating explosive; plastic melting and microscopic cratering
- Deflagrating explosives (recovered post explosion in unreacted state; like propellants in pipe bombs; rupture of vessel lead to quenching of reaction resulting in unconsumed explosive charge available for recovery.


Recovery of evidence from bodies:

- Types of injuries received by victims
- Shrapnel (fragments from explosive device may identify it)
- Victims should be examined and X rayed locate, recover and ID source
- Chemical examinations may ID explosive device


Results of explosion:

- Structural damage
- Broken gas lines
- Broken water lines
- Downed electrical lines
- Release/ production of toxic materials
- Biological issues


Primary blast injuries known as PBIs:

- Caused by large pressure differential of blast wave
shearing, implosion and acceleration/deceleration injuries
- Hollow medium filled tissues such as ears, lungs and GI at higher risk
then solid organs
- Total body disruption (TBD); amputation
- Usually occur to victims in close proximity(suicide bombers)


Secondary blast injury (SBI):

- Caused by objects accelerated by explosion
- Velocity (injury potential of projectiles based on magnitude)
- Weight of projectile, distance from source of explosion
- IEDs employ additives such as screws and nails for similar effect
- Account for majority of injuries in survivors


Modes of activation:

- Delay activation
- Victim activation
- Command activation


An explosion is:

A rapid expansion of gases resulting from a chemical or physical action that produces a pressure wave.


Tertiary Blast injury (TBI) is:

- Result of displacement of victim by blast wind.
- Victim propelled along ground, resulting in contusive blunt trauma
- Victim launched through air; may collide with stationary objects.
- Severity of TBI depend on proximity and magnitude of blast.


Quaternary Blast injury :

Result from variety of blast effects
- Burns, chemical and toxic dust poisoning, radiation exposure,
crush injury due to building collapse