April 17 – Right In The Middle

Today’s factismal: The M 7.8 temblor in Ecuador is only one of 4,000 earthquakes that happened today.

You may remember that back in March I wrote that we would probably only see one or two M 7.8 earthquakes this year. The one on March 2 was the first. And yesterday, we have the second in Ecuador. That M 7.8 temblor (temblor is what seismologists call an earthquake) happened at 6:58 PM, killing 233 people and devastating wide swaths of the country. It was the strongest event in the area in the past thirty years and the seventh great earthquake (an event with magnitude greater than M 7) in Ecuador since 1900. This earthquake released the same amount of energy as 504 Hiroshima bombs; that’s enough energy to power a typical household for 332,871 years or a hurricane for 53 seconds. That energy did enormous damage to the area, mostly because the buildings there are mainly built of brick and masonry neither of which stand up well to shaking. But the temblor was actually not that strong as earthquakes go. In the past decade alone, there have been twenty events stronger than this one (and six that were just as strong).

The area affected by the M 7.8 event (epicenter marked by a star) (Image courtesy USGS)

The area affected by the M 7.8 event (epicenter marked by a star)
(Image courtesy USGS)

Since then, there have been 10 aftershocks recorded, with magnitudes ranging from 5.8 to 4.5. In practical terms, the main event released about 100 times more energy than the biggest aftershock and about 2,000 times more energy than the smallest. Over the next few weeks, we can expect to see upward of 100 more aftershocks; the strength should gradually decline to about M2 – but we can’t rule out the possibility of an exceptional aftershock with a magnitude larger than the original earthquake.

There are a lot more small earthquakes, but the big ones release a lot more energy!

There are a lot more small earthquakes, but the big ones release a lot more energy!

As astonishing as it may be to folks who don’t study earthquakes, the Ecuador event wasn’t the only temblor yesterday; indeed, there are about 4,000 events every day! That adds up to  nearly 30,000 earthquakes each week and nearly 1,500,000 earthquakes across the globe every year. But don’t worry. It isn’t unusual. It is actually all part of how planets work.

One year of earthquakes across the world. (Image courtesy the USGS)

One year of earthquakes across the world. (Image courtesy the USGS)

We get earthquakes because the Earth is hot inside. That heat creates convection in the mantle. And the motion of the mantle drives motion of the Earth’s crust, breaking it into large rigid sections called plates. As the plates collide to form mountain ranges or scrape alongside in transform zones, they release energy as earthquakes. For Ecuador, the plates that are colliding are the Nazca plate and the South American plate. And the mountains that are being built are the Andes. Unfortunately, the earthquakes that those colliding plates create cause lots of damage.

The different layers of the Earth. Only the outer core is molten; everything else s solid!

The different layers of the Earth. Only the outer core is molten; everything else is solid!

Lots and lots of damage. Not just buildings, but lives. This event killed at least 233 people and injured many more. So this time, I’m not going to ask you to do citizen science. Instead, I’m going to ask you to do something that will help the people of Ecuador. Please give to the World Help fund (here’s their rating on Charity Navigator). The money you give will go to help those hurt by natural disasters like this to restart their lives and rebuild their homes. To learn more, go to:
http://www.worldhelp.net/

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