After Shock
Earthquakes have many effects that can be separated into two groups: primary and secondary.

Primary Effects are features that are always present in a severe earthquake.

• The ground shakes
• Roads buckle
• Buildings collapse
• Electric lines and gas mains can snap
• Large areas of ground can shift position
• Large bodies of water can rise and fall

Aftershocks are earthquakes that follow the largest shock of an earthquake sequence. They are smaller than the mainshock and within 1-2 rupture lengths distance from the mainshock. Aftershocks can continue over a period of weeks, months, or years. After the 1886 earthquake, 300 aftershocks were recorded in that area for a 2 ½ year period.

In general, the larger the mainshock, the larger and more numerous the aftershocks, and the longer they will continue.

Secondary effects are other disasters caused by the ground movement of earthquakes. Most of the damage done by earthquakes is due to secondary effects that can occur over very large regions, causing wide-spread damage.

Landslides
These occur in hilly/mountainous regions. The damage caused can range from blocked roads to possibly huge property damage and many deaths.

Soil Liquefaction
This happens when the movement caused by an earthquake forces water to seep into the material beneath a building. This causes saturated granular material to lose its strength and briefly change into a liquid from a solid. This forces the foundations of structures to become very unstable and sink into the ground.

Fires
Earthquakes can easily cause fires. Ground movements can lead to gas and fuel leaks in pipes, cutting of electrical cables, etc. The destruction of water pipes makes it harder to fight such fires should they occur. The Earthquake of 1906 in San Francisco ruptured the main water supply, and as a result, there was extensive fire damage.