It’s Time to Get Shakin’

It’s Time to Get Shakin’

Today on Earth Science for Everyone we are going to demystify another set of bad science facts. From the title of this post you can probably guess what the subject matter is about, but for those who didn’t make that connection, its Earthquakes!  Now depending on how much you paid attention in Science class and how many movies you watched, I can guarantee that at least one of these items will be news to you!

Myth #1:  Earthquakes Occur Randomly Across the Earth’s Surface.

This answer is going to back along with the blog post about volcanoes and we are going to revisit my favorite Earth Science topic: Plate Tectonics.  Yes that pesky little topic that you just can’t seem to escape is also at fault for Earthquakes.  (ha you see what I did there, fault…earthquakes…faults…oh never mind).  Anyway Earthquakes form because of friction.  The same friction that keeps our cars on the road and our butts on our couches.  So, in order for an Earthquake to form we need a source of friction. 

Well what better place to look for friction than at plate boundaries.  The tectonic plate boundaries are great sources for friction in the Earth.  Anywhere you have two masses rubbing against one another you will get friction.  But how do we get such a variation in magnitude? 

That is caused by potential energy buildup.  Who, what?  Ok, think of it like a spring,  as you compress the spring you are putting more and more energy into the spring.  This stored-up energy is what we refer to as potential energy.  Now, when you finally release the spring all that stored-up energy is released as kinetic energy.  (See this cool video for more). 

The plate boundaries do the same thing.  They are constantly adding more and more pressure to the “spring” until one of them finally let’s go and boom, Earthquake. So now you see why there needs to be a plate boundary between them.  So what about those few places where there is no plate boundary? 

Fault lines can occur anywhere on the Earth’s surface.  These lines are caused by the same mechanics you would find at a plate boundary, just on a “smaller” scale.  Fault lines are often old plate boundaries, that are weaker then the surrounding rocks.  So when pressure builds up in the area, these places are likely to be where all the energy gets released.  Think of fault lines like the cracks in a Hershey’s Chocolate Bar.  If you push the two ends of the bar in opposite directions, where will the bar break?  Along one of those lines of course!

Myth #2: The Ground Opens Up During an Earthquake

This one is both a combination of old beliefs and Hollywood.  But the answer will go along with everything I just finished saying earlier.  In order for an Earthquake to even be an Earthquake you need friction.  If the ground just opens up to gaping hole than there would be no Earthquake, you would just have a sinkhole.

But there is some reasoning behind this belief.  It comes from the fact the some Earthquakes can cause landslides and ground failures.  To the average person you may believe that the landslide is what caused the Earthquake.  But we know better than it.  So say it with me, friction causes Earthquakes.

Myth #3: Earth Shaking is Deadly

Well this is sort of a pet peeve so I will be quick.  The physical movement of the Earth during an Earthquake will not kill anyone.  It will not stop your heart or cause you to suffocate or anything like that.  Sure a handful of people may be buried under landslide debris, or fall into the ground collapse, but we are taking about the actually shaking effect.

The reason that Earthquakes are deadly is because we humans build shit that can’t withstand the effects of an Earthquake.  Almost all deaths and injuries from Earthquakes is not because the ground shook a little, it’s because the building we were in collapsed.  Or our big, collector’s edition, die-cast metal ecto-1 fell off the shelf and onto our head. 

Honestly, you can take this for what it’s worth.  It could be truthful to you, but to me the shaking doesn’t kill anybody.  It’s the bridge that fell into the water that killed somebody.

Myth#4: The Biggest Earthquake is a Magnitude 10

This one has been a myth since the dawn of human laziness. Well that and the fact that every science textbook in the World* shows the scale going from 1-10.  And while I am one the topic, why is that almost everything goes 1-10?  Do we just really like that system so much, that we limit ourselves to it? 

Well anyways back to my point here.  The reason that we don’t print the scale that high is because the scale is theoretically endless.  Although it is technically possible for an Earthquake to be a magnitude 12 (albeit EXTREMELY unlikely), most scientists agree that the upper limit is 10.  This is because the rocks we have on Earth would probably break apart before being able to store up enough energy to make an Earthquake that large, but I digress.

The scale we use to calculate the magnitude of an Earthquake is logarithmic, meaning that each number is 10X more than the one before it.  So a magnitude 2 earthquake is 10X more powerful than a magnitude 1.  And a magnitude 5 Earthquake would be 100,000 more powerful than a magnitude 1.  So you can see that although you could have a magnitude 12 Earthquake, it would be 100,000X more destructive than the 9.0 quake that hit Japan in 2011, and that probably will never happen.

(*note didn’t actually check this myself)

Myth #5: Earthquakes are Rare Events

This has got to be one of the most common misconceptions out there.  And this another reason to hate your local media outlets.  The reason for this misconception is simply the lack of attention we give to anything that isn’t “ground breaking”.  For one, the media will not cover Earthquakes from anywhere in the World unless they are disasters.  So many Earthquakes (even some large ones) will go unnoticed because if no one dies, the media doesn’t care.

 * This data is from 3/27/13-3/28/13...and if you look it up yourself you will gee the same map!

Now let’s compound the lack of global coverage with the lack of attention to small quakes.  Again unless the Earthquake is destructive (or in some cases, it occurs in a rare place) the media will not pick up on it.  If the big news networks aren’t out there telling people about the Earthquake, 95% of people won’t even know there was one.

So how do we fix this problem?  Simple, check out this website…go ahead I’ll wait.  The USGS site records hundreds of Earthquakes all over the World and reports them to this map.  You can filter this by magnitude, or by the date, and just have some fun looking at just how many Earthquakes are happening today.  Once you look here for a while, you will realize just how dynamic the planet really is.