Explosion

There are numerous ways this can happen, both naturally and artificially, such as volcanic eruptions, or two objects striking each other at very high speeds, as in an impact event.

Explosions frequently occur during bushfires in eucalyptus forests where the volatile oils in the tree tops suddenly combust.

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.

Another type of large astronomical explosion occurs when a meteoroid or an asteroid impacts the surface of another object, or explodes in its atmosphere, such as a planet.

This occurs because the two objects are moving at very high speed relative to each other (a minimum of 11.2 kilometres per second (7.0 mi/s) for an Earth impacting body[3]).

Chemical explosions (both intentional and accidental) are often initiated by an electric spark or flame in the presence of oxygen.

Examples include an overheated boiler or a simple tin can of beans tossed into a fire.

Note that the contents of the container may cause a subsequent chemical explosion, the effects of which can be dramatically more serious, such as a propane tank in the midst of a fire.

Unless the reaction occurs very rapidly, the thermally expanding gases will be moderately dissipated in the medium, with no large differential in pressure and no explosion.

As a wood fire burns in a fireplace, for example, there certainly is the evolution of heat and the formation of gases, but neither is liberated rapidly enough to build up a sudden substantial pressure differential and then cause an explosion.

[6] It is the rapid liberation of heat that causes the gaseous products of most explosive reactions to expand and generate high pressures.

Heats of formations for solids and gases found in explosive reactions have been determined for a temperature of 25 °C and atmospheric pressure, and are normally given in units of kilojoules per gram-molecule.

A material in which the first three factors exist cannot be accepted as an explosive unless the reaction can be made to occur when needed.

Fragments could originate from: parts of a structure (such as glass, bits of structural material, or roofing material), revealed strata and/or various surface-level geologic features (such as loose rocks, soil, or sand), the casing surrounding the explosive, and/or any other loose miscellaneous items not vaporized by the shock wave from the explosion.