Sympathetic detonation 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 test s . If detonator s with primary explosive s 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 explosive s 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 panel s 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 shrapnel s . 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 . Military . Sympathetic detonations may occur in munition s stored in e . g . vehicles , ships , gun mounts , or storage depots , by a sufficiently close explosion of a projectile or a bomb . Such detonations after receiving a hit caused many catastrophic losses . To prevent sympathetic detonations , minimal distances ( specific for a given type of the mine ) have to be maintained between mines when laying a minefield . Spallation of materials after an impact on the opposite side may create fragments capable of causing sympathetic detonations of stored explosives on the opposite side of an armour plate or a concrete wall . Transfer of the shock wave through the wall or armour may also be possible cause of a sympathetic detonation . Class 1 . 1 solid rocket fuels are susceptible to sympathetic detonation . Conversely , class 1 . 3 fuels can be ignited by a nearby fire or explosion , but are generally not susceptible to sympathetic detonation . Class 1 . 1 fuels , however , tend to have slightly higher specific impulse s , and therefore are used in those military applications where weight and / or size is at a premium , e . g . on ballistic and cruise missile submarine s . Sympathetic detonation can be used for the destruction of unexploded ordnance , improvised explosive device s , land mine s , or naval mine s by an adjacent bulk charge . Special insensitive explosives , such as TATB , are used in e . g . military applications to prevent the sympathetic detonations . Examples . During the 1967 USS Forrestal fire , eight old Composition B based iron bomb s cooked off . The last one caused a sympathetic detonation of a ninth bomb , a more modern and less cookoff - susceptible Composition H6 based one . The Russian submarine Kursk explosion was probably caused by a sympathetic explosion of several torpedo warheads . A single dummy torpedo VA - 111 Shkval exploded ; 135 seconds later a number of warheads simultaneously exploded and sank the submarine . Civilian . In rock blasting , sympathetic detonations occur when the blastholes are sufficiently close to each other , usually 57 mm or less , and especially in rocks that poorly attenuate the shock energy . Ground water in open channels facilitates sympathetic detonation as well . Blasthole spacing of 300 or more millimeters is suggested . However , in some ditch blasting cases sympathetic detonations are exploited purposefully . Nitroglycerine - based explosives are especially susceptible . Picric acid is sensitive as well . Water gel explosive s , slurry explosive s , and emulsion explosive s tend to be insensitive to sympathetic detonations . For most industrial explosives , the maximum distances for possible sympathetic detonations are between 2 – 8 times of the charge diameter . Uncontrolled sympathetic detonations may cause excessive ground vibrations and / or flying rocks . The spread of shock waves can be hindered by placing relief holes – drilled holes without explosive charges – between the blastholes . The opposite phenomenon is dynamic desensitization . Some explosives , e . g . ANFO , show reduced sensitivity under pressure . A transient pressure wave from a nearby detonation may compress the explosive sufficiently to make its initiation fail . This can be prevented by introducing sufficient delays into the firing sequence . A sympathetic detonation during mine blasting may influence the seismic signature of the blast , by boosting the P - wave amplitude without significantly amplifying the surface wave . References .