How Earthquakes Happen
In light of last week’s horrible earthquake in Haiti, I thought I’d talk a little about the forces of nature behind such events. Despite what you may have read or heard on TV via the mouth of a certain science-ignorant televangelist, earthquakes are entirely natural events that happen when some part of Earth’s surface experiences violent vibration. What causes the vibration?
The vibration is caused when energy is released in Earth’s crust. This energy may be generated when segments of the crust are somehow jostled. A nearby volcanic eruption can release energy that vibrates Earth’s crust. In some rare cases, an underground explosion or collapse of an underground cavern can also cause an earthquake.
The most destructive quakes — like the one in Haiti — are caused by dislocations of the crust. At first, the crust will bend (and remember, the crust is made of rock and rock can bend before it will break). Eventually, if the stress is strong enough, if the energy released is strong enough, the rocky crust will snap. When that happens, you get vibrations called seismic waves. These seismic waves travel out from the place where the crust broke, and they shake the upper part of the surface. That shaking is what damages and/or destroys buildings, highways, and bridges. Some earthquake waves can actually be heard, but mostly they can be felt. The U.S. Geologic Survey has a wonderful primer on earthquakes that I recommend you check out.
Earthquakes are part of a larger process that modifies the surface of our planet over time — that process is called tectonism. It’s the faulting or folding or other deformation of the outer layer of a planet. Tectonism is driven by forces within the world it affects (and yes, other places have tectonism). Earth, for example, has tectonism driven by heat from the core, which affects the layers above it. Our planet’s continents ride on rock plates that move against each other as the planet turns. Motions of the plates reverberate through the layers of rock they carry, and this can cause earthquakes (through a complex chain of events). They also (over millions and millions of years) can do such things as form mountain ranges (the Himalayas are a good example).
How do we know all this? Scientists monitor the motion of Earth’s crust through a variety of methods including seismic sensors (such as GPS ground sensors, see the map at left) and core samples of rock that have been drilled out. By looking at the rocks in the cores, they can understand the formation history of the rocks and any stresses that have been applied to them by movements of the crust. They can also look at surface features and by understanding how they were formed, also understand the crustal movements that caused them to form. It’s pretty standard geology work.
Earthquakes, as terrible as they can be, are a natural phenomenon caused by natural processes within our planet. We see evidence for quakes elsewhere in the solar system, as well. Understanding earthquakes helps us understand the interiors of the worlds they affect and the science is fascinating.
The effects on humans on Earth when a quake hits are not so fascinating. They’re downright sad and horrifying. All the understanding of the science doesn’t help us when we are confronted by the pain and suffering these geological actions cause. What we as humans living on an earthquake-prone planet should do is help those who are affected by others who are hurt or damaged during a quake. What we shouldn’t do is make hateful statements that contain NO scientific accuracy about why earthquakes occur. That’s what the televangelist I referenced above did. He proved his ignorance and hateful politics pretty well by blaming the earthquake on what he thinks is voodoo (he has no evidence for this). He really thinks that the actions of Haiti’s earlier inhabitants in seeking political freedom caused the earthquake. He also has no evidence for that statement either.
I mean, this guy actually believes what he’s saying? If so, he’s been pwnd by some pretty serious ignorance. And that calls into question the accuracy of everything else he “preaches”.
As a representative of the Christianist faction in American politics, this “man” comes across as representing millions of people who are Christians, who ARE scientifically literate and, as far as I know, DON’T hate on the basis of tectonic motion.
Why anybody would take this jerk seriously, particularly in matters of science, is beyond me. I wouldn’t go to a banker for medical advice. I wouldn’t go to a scientist to learn about theology. It’s been made abundantly clear that I certainly shouldn’t ever go to a preacher to learn about science. Above all, I wouldn’t trust a hateful man who primarily makes his money off of other people’s faith (and lives in wealth and luxury on the proceeds of his “work”) to know anything about human dignity, morality, ethics, and sympathy — much less science or natural processes.
Earthquakes are not caused by voodoo. Quakes are not the actions of a deity whose creator-followers make him out to be petulant and angry. In fact, there’s no scientific proof that deities are involved in earthquakes. Anybody who tells you that some annoyed sky daddy causes earthquakes to punish people with suffering and death is an idiot. Pure and simple. Earthquakes are an entirely natural process that occurs on Earth. Science has done an excellent job of telling us how they work and what causes them.
If you want to help people affected by the Haitian earthquake, there are a number of places online to guide you to the right place. The Red Cross and Doctors Without Borders are good places to start. I’m sure there are others — so, if you can help in a positive way, please do.
