What Are Earthquake Hazards?

When people think about earthquakes their first thought is usually the shaking of the ground that causes buildings to collapse. This is definitely one of the hazards associated with an earthquake. But there are a lot of other hazards and “problems” that are caused when Mother Earth decides to shake and tremble.

It may not help much to know this, but an earthquake isn’t all that dangerous to an individual. How can this be, you ask? The shaking won’t kill you if you are standing in an open space and if the ground doesn’t open up beneath you. The hazards to life and health from an earthquake have a different source.

Let’s look at the effects of an earthquake, one by one. First of all, the ground shakes. This can be dangerous primarily because buildings and other tall structures can be damaged or may collapse when the ground moves. If the surface drops significantly (subsides) the danger to living things in the area is intensified.

If the Earth moves sufficiently, the soil may actually fail to support any weight at all. Scientists say the soil “liquefied” because it mixes with water under the surface during the shaking. Buildings, highways etc. fall, lean over and break apart. This failure of man-made structures is responsible for many of the injuries and deaths during an earthquake.

Another earthquake hazard is movement of the ground. In some cases, this movement is a landslide or a mudslide in a hilly region. During some earthquakes the ground might actually split open or move along what is known as the fault line. This is what we see when roads are separated by huge cracks or when we look at photos from a city and the streets are cracked and broken into different levels.

Nearly everyone in the world remembers the tsunami that struck numerous countries in the Indian Ocean region in 2004. When the earth moves under the surface of the ocean it can create huge waves. The flooding that follows is one of the most dangerous hazards of an earthquake. Even if the earthquake doesn’t cause an ocean tsunami the event can break open a dam or an earthen levee, which will also produce flooding.

An earthquake hazard that many people don’t think about immediately is fire. In fact, the earthquake that destroyed much of San Francisco more than 100 years ago created fires that were responsible for much of the damage. In modern cities, natural gas lines, electrical lines and fuel tanks can be the source of fires and explosions. If water service is disrupted it may be very difficult to stop flames from destroying buildings and taking lives.

As we can see from this brief look at earthquake hazards, most of the danger to human beings and animals comes from the failure of man-made structures. A person can be buried in the rubble of a building, drown in a tsunami, buried under a mudslide from the mountainside or even be burned when a building catches on fire. When we think of earthquake hazards, we have to look past the earthquake itself to see where the real danger lies.