Earthquake Damages
Some damages are not due directly because of the earthquake. Some, like fires and tsunami, are an indirect result of the quake. For example, the quake can cause a gas main to break, which then can lead to a fire.
Fires
The most common cause of fires after an earthquake is a ruptured gas line. If you smell natural gas, DO NOT light a fire or cause any kind of spark - doing so can ignite the gas and cause a fire and/or explosion. It is always a good idea to shut off the gas main to your house after an earthquake if you do not already have an automatic shut-off valve installed. In most cases, your gas company will install one either free of charge or at a low cost.
Tsunami
Despite what the movies may show, tsunami cannot be caused by an earthquake on land, no matter the size (sorry!). Instead, tsunami are caused by either undersea earthquakes, undersea (or coastal) landslides, island volcanic eruptions, and impacts from space that land in the ocean. In each case, the water column is displaced and a tsunami is generated. It is like the ripples that form when a pebble is dropped into the water. The waves generated radiate outwards from the point of origin. They have very large wavelengths, but low amplitudes in the open ocean. Most ships out at sea can't tell the difference between a regular wave and a tsunami. When the tsunami wave aproaches the shore, it's long wavelength translates into a very tall wave that rushes onto shore at a high rate of speed. The wave floods low-lying areas, picking up everything not secured, destroying structures, and killing people and animals.