Fuel-air explosive
A fuel-air explosive (FAE) device consists of a container of fuel and two separate explosive charges. After the munition is dropped or fired, the first explosive charge bursts open the container at a predetermined height and disperses the fuel (also possibly ionizing it, depending on whether a fused quartz dispersal charge container was employed) in a cloud that mixes with atmospheric oxygen (the size of the cloud varies with the size of the munition). The cloud of fuel flows around objects and into structures. The second charge then detonates the cloud, creating a massive blast wave. The blast wave destroys reinforced buildings and equipment and kills and injures people. The antipersonnel effect of the blast wave is more severe in foxholes and tunnels, and in enclosed spaces, such as bunkers and caves.
Fuel-air explosives were first developed by the United States for use in Vietnam. In response, Soviet scientists quickly developed their own FAE weapons, which were reportedly used against China in the Sino-Soviet border conflict, and against the Mujahideen in Afghanistan. Since then, research and development has continued and currently Russian forces field a wide array of third-generation FAE warheads.
The type of bomb best suited for tunnels is a Thermobaric Bomb. This type of device uses a small explosion to spread the fuel air mixture which then ignites to form the much larger explosion.
That would explain the waveform in the pic.
https://en.wikipedia.org/wiki/Thermobaric_weapon