@ RescueRanger,
Very good points in your analysis above.
i have a question about the last point, i.e. seat of blast... AKA "crater". In case of a vehicle borne explosive device, since the device is (at the time of explosion) some height from the ground, contained in a dynamic container- the car (not secured to something immobile) and in this case on a built-up surface (the road/tarmac); most of the energy of the explosion would be dissipated laterally and upwards. Any down ward dispersion would have reflected off the hard surface. Hence no crater or little damage. Am i correct in my inference? Please correct me if i am wrong.
Very good observation Captain, and if you consider the conventional vbied design then yes you would be correct to a great degree, however in Pakistan as with Afghanistan and Iraq the design of VBIEDs has evolved.
One of the most common is to pack the undercarriage of the vehicle with high explosive (can within a can) or just under voids of the driver and passage seats.
One of the constructs we come across is the a collection of arty shells in a serial (similar) to this:
As they say professionalism differentiates the "men" from the "boys". This technique is the favorite of AQN and it's affiliates. Using this technique allows the terrorists to transport milspec high explosive in a smaller vehicles and deliver a payload that would normally be "greater" to the standoff expected from such a vehicle. (refer to chart bellow).
VBIED craters are nothing new, it just depends on the load, the positioning of the charge and the force of the blast.
Rather that go deep into the science of it, consider the following:
Charge placement, load and environment can greatly determine the effects of the blast.
1. Frontal Load Placement effects:
2. Rear Load Placement effects:
3. Cabin Placement:
If you consider the concept of a shaped charge... The force of the explosive is being pushed downwards by the container "vehicle" and depending of the type and quantity of the explosive, the surrounding environment and the design of the device it is not uncommon to expect a crater at the site of a vbied of such magnitudes.
Hope that helped and sorry if i babbled on.