Fault Slippage- The rock on either side of a fault may barely or may suddenly heave 20 ft or more. Structures built over a fault line may be suddenly wrenched apart. The shifting earth may also loosen soil and rocks causing landslides. Fault slippage may also break down the banks of rivers and lakes, causing flooding. In Hawaii this type of damage occurs when the land mass of a volcano presses down and out on the Pacific plate as this tectonic plate pushes northeastward. When pressure builds up with these two opposing forces, slippage occurs. The most destructive types of earthquakes in Hawaii occur in this manner.
Ground Shaking- Ground shaking causes structures to sway from side to side, bounce up and down, and move in other violent ways. Structures may slide off foundations, collapse, or be torn apart. Contents and furnishings may be tossed around in disarray and smashed. In Hawaii the movement of underground magma frequently causes this type of damage.
Liquefaction- In areas with soft wet soil, liquefaction may intensify earthquake damage. This occurs when strong ground shaking causes wet soil to act like liquids rather that solids. Anything on top of liquified soil may sink into the softened earth. Liquified soil may also flow toward lower ground, creating a destructive mudflow. This is not a common occurence in Hawaii's earthquakes.
Tsunamis- Earthquakes on the ocean floor can give a forceful push to the surrounding water, creating on or more large destructive waves called tsunamis. These waves are also known as seismic sea waves and are incorrectly called tidal waves (these waves have nothing to do with tides.) Tsunamis may reach heights of over hundered feet when the approach shallow water near shore. They can travel great distances, flooding coastal areas thousands of miles from their source.
Structural Hazards- Structures collapse during a quake, especially if they are too weak or rigid to resist violent rocking motions. Tall buildings may vibrate wildly and knock into each other.
Fire- Fire is a major cause of damage to both property and human life during earthquakes. Quakes can easily rupture gas or power lines, igniting multiple fires. The 1906 San Francisco earthquake was made all the more disasterous because of a fire that raged for three days following the quake itself. The city of Kobe, Japan was peppered with numerous fires following the tremendous earthquake which struck in 1995. Containment was made difficult due to the collapse of buildings and highways that blocked the efforts of firefighters.
Loss of Power, Comunication, and Transportation- Rescue teams and ambulances may be hampered in their efforts by the loss of power, comunication, and transportation. This may lead to increased deaths and injuries. Businesses and government offices may lose records and supplies, hampering recovery efforts.
Other Hazards- Toxic chemical spills and falling objects, such as tree limbs, bricks and glass may prove to be hazardous as a result of earthquakes. Water supplies may be contaminated by sewage seeping from broken sewage lines. Drinking this impure water may lead to cholera, typhoid, dysentery, and other serious diseases.