Natural

Explosions can occur in nature. Most natural explosions arise from volcanic processes of various sorts. Explosive volcanic eruptions occur when magma rising from below has much dissolved gas in it; the reduction of pressure as the magma rises causes the gas to bubble out of solution, resulting in a rapid increase in volume. Explosions also occur as a result of impact events.

Chemical

main: Explosive material The most common artificial explosives are chemical explosives, usually involving a rapid and violent oxidation reaction that produces large amounts of hot gas. Gunpowder was the first explosive to be discovered and put to use. Other notable early developments in chemical explosive technology were Frederick Augustus Abel's development of nitrocellulose in 1865 and Alfred Nobel's invention of dynamite in 1866.

Nuclear

main: Effects of nuclear explosions

A nuclear weapon is a type of explosive weapon that derives its destructive force from the nuclear reaction of fission or from a combination of fission and fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives available, with a single weapon capable of destroying an entire city.

Electrical

A high current electrical fault can create an electrical explosion by forming a high energy electrical arc which rapidly vaporizes metal and insulation material. Also, excessive magnetic pressure within an ultra-strong electromagnet can cause a magnetic explosion.

Vapour

Boiling liquid expanding vapour explosions are a type of explosion that can occur when a vessel containing a pressurized liquid is ruptured, causing a rapid increase in volume as the liquid evaporates.

Astronomical

Solar flares are an example of explosion common on the Sun, and presumably on most other Nebulas as well. The energy source for solar flare activity comes from the tangling of magnetic field lines resulting from the rotation of the Sun's conductive plasma.

Mechanical

Strictly a physical process, as opposed to chemical or nuclear, eg, a the bursting of a sealed or partially-sealed container under internal pressure is often referred to as a 'mechanical explosion'. Examples include an overheated boiler or a simple tin can of beans tossed into a fire. A BLEVE (see above) is one type of mechanical explosion, but depending on the contents of the container, the effects can be dramatically more serious - consider a propane tank in the midst of a fire. In such a case, to the limited effects of the simple mechanical explosion when the tank fails are added the chemical explosion resulting from the released (initially liquid and then almost instanteaously gaseous) propane in the presence of an ignition source. For this reason, emergency workers often differentiate between the two events.