Blast Over-Pressure
Definition
The shock-wave pressure above ambient atmospheric pressure. Mapped in concentric zones around the seat: Zone I (over 70 kPa, total destruction), Zone II (severe damage), Zone III (under 7 kPa, moderate damage).
- Definition
- Shock-wave pressure above ambient atmospheric
- Zone I
- Over 70 kPa, total destruction
- Zone III
- Under 7 kPa, moderate damage
- Field
- Explosion and arson investigation
Common questions
How do investigators use the concentric overpressure zones at a scene?+
Mapping damage severity outward from the seat against the expected zone boundaries helps investigators estimate the explosive charge weight and confirm the location of the seat, since the extent and pattern of structural and material damage should scale with distance in a predictable way.
Why does overpressure zoning differ between an open-air and a confined-space explosion?+
In a confined space, reflected shock waves from walls and ceilings can locally amplify or reduce pressure compared to the simple concentric pattern seen in open air, so investigators adjust their interpretation of damage zones based on the surrounding structure.
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