A Whole Lot of Shaking Going on

We had a little earthquake last week. Its 6 a.m. epicenter was near the town of Columbus, North Carolina. It wasn’t much, just a 3.1 magnitude shaking for a few seconds, but the local paper reported it was enough to make some poor child up there wake up thinking that his brimstone preacher was right and the end of time had arrived on schedule.

It touched me to hear about that little boy’s fear of time ending, but I wanted to drive up there and do a little mission work, preach a little geology at him. I wanted to make sure he was as versed in the great story of the earth as he was in Biblical apocalypse.

Earthquakes, even more than the poor, will be with us always, and rather than signs of the end of time, they witness to time’s vast sweep. They are part of what geologists call “the big picture,” a narrative of billions of years of deep time that guides the science’s understanding of the planet’s localized burps and gurgles.

As the geologists have come to understand it, the movement of the earth originates from faults, either shallow or deep in the crust. When two faulted blocks of rock slip a little, we feel it on the surface as a quake. As the Upcountry found out once again last week, Alaska and California aren’t the only places where quakes can shake us awake. The whole continent is faulted. Some places-like our West Coast-have more active faults because they are at the edges of two huge continental plates that are currently slamming against each other. One plate collides with the other and they thrust above or plunge below the huge plate of rock next door. This collision zone is so active that earthquakes happen on a daily basis. “The big one” is what everyone’s waiting on in California, and when it happens it will feel for a moment like the Second Coming.

But when the smoke clears and the damage is assessed, even that huge West Coast natural disaster will be seen as what it is-another small brush stroke in “the big picture” that geologists have painted for the whole planet.

We live on the calmer side of the continent. Our super active earthquake time was hundreds of millions of years in the past. That’s when the plate Africa is riding on was grinding against our east coast. Now Africa is in reverse, and the Atlantic Ocean has filled the great rift between the two plates. Things in our neighborhood have settled down, but not entirely. There are still old faults deep in the earth, and they still move.

On the evening of August 31, 1886 the city of Charleston experienced the most destructive earthquake ever recorded east of the Mississippi. It was not quite as intense as the 1811 New Madrid, Missouri earthquake that made the Mississippi reverse its course in a move even Moses would envy, or the 1906 San Francisco quake, but the evidence tells us it was big: an estimated 7.6 on the not-yet-invented Richter Scale.

The quake was miles deep in the earth, and the rock on each side of the fault was displaced almost six feet. The sediments of the coastal plain where Charleston is built turned to mush over the quake area and rolled like waves on the sea.

The earthquake’s results were catastrophic: 14,000 brick chimneys collapsed, ninety percent of the brick buildings in Charleston were damaged, and 110 people were killed. There was damage in all the large towns within 100 miles of Charleston. In Columbia people reported difficulty walking during the quake.

If you visit Charleston on a regular basis you should not worry too much about the next “big one” there. In “the big picture” the odds are pretty small you’ll experience it. Geologists have calculated that the 1886 earthquake was a one in 1,000 year event. That doesn’t mean another big one can’t happen tomorrow, just don’t bet on it.

And what of the “end of time” that little boy in Columbus is worried about? I don’t think anyone has successfully calculated the odds on that. Like many of the human hopes and fears in our day-to-day lives, that’s a matter of faith not science.

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