Wiktionary
n. (context military English) Detonation of a charge by exploding another charge adjacent to it.
Wikipedia
A sympathetic detonation (SD, or SYDET), also called flash over, is a detonation, usually unintended, of an explosive charge by a nearby explosion. Sympathetic detonation is caused by a shock wave, or impact of primary or secondary blast fragments.
The initiating explosive is called donor explosive, the initiated one is known as receptor explosive. In case of a chain detonation, a receptor explosive can become a donor one.
The shock sensitivity, also called gap sensitivity, which influences the susceptibility to sympathetic detonations, can be measured by gap tests.
If detonators with primary explosives are used, the shock wave of the initiating blast may set off the detonator and the attached charge. However even relatively insensitive explosives can be set off if their shock sensitivity is sufficient. Depending on the location, the shock wave can be transported by air, ground, or water. The process is probabilistic, a radius with 50% probability of sympathetic detonation often being used for quantifying the distances involved.
Sympathetic detonation presents problems in storage and transport of explosives and ordnance. Sufficient spacing between adjacent stacks of explosive materials has to be maintained. In case of an accidental detonation of one charge, other ones in the same container or dump can be detonated as well, but the explosion should not spread to other storage units. Special containers attenuating the shock wave can be used to prevent the sympathetic detonations; epoxy-bonded pumice liners were successfully tested. Blow-off panels may be used in structures, e.g. tank ammunition compartments, to channel the explosion overpressure in a desired direction to prevent a catastrophic failure.
Other factors causing unintended detonations are e.g. flame spread, heat radiation, and impact of shrapnels.
A related term is cooking off, setting off an explosive by subjecting it to sustained heat of e.g. a fire or a hot gun barrel. A cooked-off explosive may cause sympathetic detonation of adjacent explosives.
Usage examples of "sympathetic detonation".
In truth, he hardly expected to set off a string of daisy-chained claymores by sympathetic detonation of the HE.
Unfortunately, because of something we call sympathetic detonation, the hydrogen bombs also go poof!
If there were a sufficiently powerful explosion close by it might go up by sympathetic detonation.
He did not have the chance to do anything heroic because the mine he stepped on caused the sympathetic detonation of his 40-mm grenades, killing him instantly.
I think it's meant to blow up the twister in sympathetic detonation if the twister's own time mechanism doesn't work.
That there was an inherent risk in this Larsen was well aware: a stray bullet or shell -- or perhaps not so stray -- could well trigger the detonating mechanism of one of the depth charges, which would inevitably send up the other charges in sympathetic detonation.