Plate tectonics: convergence of an oceanic pla...

Earthquakes and Plate Tectonics

Earthquakes. Tectonic Plates. What Causes Earthquakes?

When I was in high school, earthquakes were explained as disturbances from the movement of molten lava below the earth’s surface .

Eruptions of molten lava sometimes became volcanos.

Tsunamis were tidal waves caused by storms at sea

Mountains were rooted in granite to the core of the earth, from which they had erupted.

Tectonic Plates – A New Theory

The year I graduated, 1965, scientists decided, after more than 20 years of study, that the surface of the earth moves. They call it plate tectonics. And, this is what causes earthquakes, volcanoes and tsunamis.

Sure, there is still molten lava beneath the earth’s surface. But what is really happening is that the earth’s crust shifts across the surface of the planet because of the difference in temperatures at and below the surface.

They had started noticing in the 1940s that the ocean floor moved. They called it continental drift.

It helped explain their observation that the East Coast of South America looked surprisingly like the West Coast of Africa.

However, only a few scientists made the leap to conclude the continents must once have been joined.

Oceans Shrink and Grow

Not only did the ocean floor move, but it was changing size. After lengthy observations, they found out that the Atlantic Ocean is growing and the Pacific Ocean is shrinking.

Like a conveyor belt, the floor of the ocean rises with the outpouring of molten lava from below the surface and then drops into a trench under the water.

Earth Is Staying the  Same Size

Unlike what the scientists first expected, the earth is not growing in size with the eruption of the molten lava.

It is just shifting where the rock is, from inside the earth to outside, with a disruption of the sea, which causes tsunamis, like this year’s tsunami in Japan.

On March 11, 2011, a 9.0 magnitude earthquake caused a 33-foot high tsunami on the coast of Japan. Click here to read more about historic tsunamis, including the recent one in Japan.

Or, a disruption of the land, like the rare earthquake the Eastern seaboard experienced this past summer.

A 5.8 on the Richter scale, the epicenter of the August 23, 2011 earthquake was Mineral, Virginia. Click here to read more about earthquakes in Virginia.

Keeping Up with Science

I didn’t study science again after a course my Freshman year in college. The textbooks and teacher program plans had not yet caught up with this new theory of plate tectonics.

It was a casual conversation with the mother of another piano student that clued me in to this change. I overheard her describing what causes earthquakes to her son.

Plate tectonics? The earth’s crust shifting over the surface of the earth? She explained it as though everybody already understood this. In fact, it had been only fifteen years since the theories on earthquakes had been revised.

What differences have you found out about since you were in school?

What differences have you discovered in conversations with your grandchildren?

Have you told your grandchildren what the world used to be like?

Do they think you had a pet dinosaur as a child?

Can they imagine a world before we landed on the moon? Before cell phones were in every hand? Before we knew what caused earthquakes?

Join us in our continuing quest to understand today’s world compared to the way we were taught about it as children. Click here to follow this blog in your reader.

To you and the lovely grandchildren who are learning about the world.

Only you can teach them the difference between the enduring values that last and the new understanding that comes from studying our world.

Carol Covin, “Granny-Guru”

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandchildren

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