Ever wonder why some earthquakes are literally earth-shattering, while others go unnoticed? This lesson will highlight the contributing factors that determine whether earthquakes register at all or are catastrophic occurrences.
What Is an Earthquake?
An earthquake is a violent shaking of the ground caused by motions of the Earth’s crust.
The Earth’s surface might look solid and stationary, but it really isn’t. The Earth’s crust isn’t a single, unbroken surface. Rather, it’s broken down into a lot of sections, like cracks in a smashed window. We call these tectonic plates, the pieces that make up the whole of the Earth’s crust. What’s more, those parts are always moving.
The Earth’s plates shift toward each other, away from each other, or alongside each other, depending on which plates we’re talking about. And these motions can cause violent destructive events, including earthquakes and volcanoes.Earthquakes happen either when two plates collide with each other or when two plates slide alongside each other. This is why California has so many earthquakes: there is a plate boundary called the San Andreas Fault that lies right along the coast. The sliding motion of the fault creates friction along it, resulting in a lot of tectonic movement and, as a result, earthquakes.
But why do California’s earthquakes rarely cause huge destruction? Why do so few people die in American earthquakes, but so many do in other countries, like Nepal? Today, we’re going to talk about the factors that affect the impact of an earthquake.
Factors that Affect the Impact of an Earthquake
There are seven main factors that affect the impact of an earthquake:
Some earthquakes are just bigger than others. In fact, earthquakes hit the United States every single day, but most are too small to notice. We know they occur because of seismographs, sensitive devices that detect tremors in the ground, and the application of the Richter scale, which rates earthquakes on a scale of 1 to 10. The most severe earthquake ever recorded was in Valdivia, Chile, in 1960 and registered at 9.
5 on the Richter scale, though, strictly speaking, the scale doesn’t have an end point.
Earthquake intensity is affected by both the distance along the surface of the Earth and how deep the earthquake is below the Earth. There have been earthquakes that were very severe but didn’t cause much damage, because they occurred a long way from places that humans live. Earthquakes can also hit anywhere from the surface to about 450 miles below the surface.
By the time a deep earthquake has reached us, its energy has often dissipated through the ground, leaving little left to do damage.
Another big deal is population density. If the earthquake hits in an area where people are spread out, the impact will be much smaller, since fewer people will be affected. However, if it occurs in a dense metropolitan area, a larger number of people will be affected.
Perhaps the most well documented factor is development level. When an earthquake hits a poor country, the impacts tend to be disastrous. There are many reasons for this.
The buildings in poor countries are typically not earthquake-proof, because building such structures is expensive. This causes a large number of deaths when buildings collapse. But the aftermath can often be the worst part. With limited funds and resources, cleaning up after an earthquake can be a daunting prospect and can take a very long time. If electricity and water supplies are not fixed quickly enough, the death toll can rise.
When an area has poor communication links, it can be difficult for rescue teams to get in and out and to communicate with each other. After all, how do you hear that people are trapped in some rubble if there’s no way to pass on the message?
Time of Day
When the earthquake happens during the span of the day plays a role in its impact. Time of day is important, because it determines where people are. At work in their offices or at home in their houses? Are they awake or asleep? This affects their ability to react to the disaster.
Time of Year
The time of year is also a factor, particularly when it comes to the aftermath of the earthquake. For instance, If people are left homeless by an earthquake, they are more likely to freeze to death in the winter. In the extreme heat of summer, they could suffer dehydration. All these things have a big impact on how many people survive.
An earthquake is a shaking of the ground, usually suddenly and violently, that can cause a lot of damage. It happens when two of the Earth’s tectonic plates hit each other or slide alongside each other.
There are seven main factors that determine the impact of an earthquake:
- Distance (along the surface and depth)
- Severity (measured by the Richter scale)
- Population density
- Development (building quality, financial resources, healthcare, infrastructure, etc.)
- Communication links
- Time of day (where people are located and whether they’re asleep or awake)
- Time of year (people out in the cold may not survive, etc.)
Some earthquakes pass without incident, and others cause huge damage, destruction and loss of life.