Following the Beirut explosion that occurred this week, at least 130 people were killed and thousands were injured as the toll continues to rise. In an explosion such as this, there are many different ways for injuries to occur, the initial shock wave move so fast, it travels at least 20 times faster than the speed of sound, leaving those within its vicinity no time to prepare before being either being injured by the wave itself, or by damage caused by surroundings.
The experience of being hit by a blast wave following such an explosion can be likened to a man standing at the bottom of the ocean, and being picked up by a wave and thrown in to the air, according to Prof. Nir Fink former head of the IDF's Medical Corp Division of Acoustics, who offers a list of the six most common ways an explosion can cause injury.
The first injury is perhaps the most obvious; damage caused to the body by shrapnel, or flying and falling objects. These are often more intensified when people are enclosed in a vehicle such as a bus, or a house. Prof. Fink advises that if someone is in such a situation and there is forewarning of the explosion, people should open doors and windows, allowing for the shock wave to pass through. They then should lay down, reducing exposure to flying objects.
This leads to the second injury: infection. As there are many ways in which people can come in contact with foreign objects that cause open wounds, infection is a prominent health complication following experiencing an explosion. After an explosion, access to immediate and needed health services can be limited amid chaos; injured people may not be easily found, and when people do make it to surrounding health services or first aid on the ground, those services are often over flowing by the influx of people. Injuries left untreated allow for an increased risk of infection.
One way people can be injured by unknown foreign objects, is by the shock wave picking them up and throwing them into the air; the third cause of injury. A blast wave following an explosion can lift someone up and throw them tens of meters into the air, throwing them into buildings, walls, cars, or any other surrounding object. Often times surrounding objects are picked up landing on people, crushing them as they land.
The fourth cause of injury is damage to body parts wherein air passes through, such as intestines, lungs and sinuses, can be caused due to air pressure differences between internal organs and external pressure. Damage to blood vessels as an effect of the shock wave can also occur, causing internal bleeding and even death due to no external signs of injury.
The fifth cause of injury can occur as the shock wave moves away from the heart of the explosion, it begins to slow down and weaken. Eventually it reaches a speed slower than the speed of sound. After the body is thrown tens of meters into the air, the sound can be heard causing ensuing injuries to the auditory system, such as ruptured ear drums.
After the Beirut explosion, videos were posted showing people being thrown forward with great force and then backwards in the opposite direction. This is due to a suction phenomenon which can be explained by a vacuum created as a result of air being pushed through the human body and the surrounding environment, creating a vacuum (such as in space), which in turn causes air suction in the opposite direction pulling people and objects backwards.