 In contrast, a seismic bomb is dropped from high altitude to attain very high speed as it falls and upon impact, penetrates and explodes deep underground, causing massive caverns or craters known as "camouflets", as well as intense shockwaves.In this way, the seismic bomb can affect targets that are too massive to be affected by a conventional bomb, as well as damage or destroy difficult targets such as bridges and viaducts.Earthquake bombs were used towards the end of World War II on massively reinforced installations, such as submarine pens with concrete walls several meters thick, caverns, tunnels, and bridges.