REVIEW: Earthquake Hazards

Earthquake Hazards

Earthquakes can be very dangerous, destructive and damaging. However, very little of the damage of an earthquake comes directly from the shaking. For example, hundreds of thousands of people died in the 2010 earthquake in Haiti, but, most of the fatalities were caused by buildings collapsing. Loss of infrastructure and access to important resources, such as clean water supplies, creates destructive conditions that can have long-lasting effects. 

Secondary damage from earthquakes can include fire. Ruptured gas lines can cause fires to start, and damage to water lines broken in earthquakes can prevent those fires from being put out in a timely manner. This is what happened in the 1906 San Francisco earthquake: the city burned for 4 days and destroyed 80% of the city. 

Another form of damage that results from earthquakes is liquefaction. Sometimes, when water-saturated soil and sediment under a building, road, or other structure is shaken heavily by seismic activity, the extremely wet material begins to move as though it were a liquid. This movement, called liquefaction, can cause buildings to sink or slide as their weight is no longer supported. Underground storage tanks, as well as gas, water and sewer lines can be moved or forced to the surface during liquefaction. 

Mass movements such as landslides and mudflows are also common during and after an earthquake, and can cause damage to roads, bridges and buildings. Tsunamis can also occur if an earthquake occurs on the seafloor.