By: Eileen Marable
A 7.1 magnitude earthquake hit the Pacific just between Papua New Guinea and the Solomon Islands on Thursday. This follows on the heels of the 7.8 quake in Nepal. A look at daily activity shows smaller quakes happening all over the world, especially in the infamous “Ring of Fire” region around the edges of the Pacific Ocean where tectonic activity is especially high.
What is happening when these earthquakes hit? Though it might not feel like it to us, the crust and mantle –essentially the “skin’ around the earth’s inner cores are always slowly moving. The pieces that make up these layers are bumping up against each other as they travel; the areas where they make contact are called fault lines.
When two plates of crust get stuck against each other, the energy of the movement builds up. Eventually that stored up energy is released with force when the two pieces finally come unstuck. The location where the energy is released is called the hypocenter under the surface of the crust, and the epicenter on the surface. The energy released heads outwards from the center, shaking the earth in waves.
One plate may slip up while the other slips down under the other in what’s called a subduction zone. In fact, in the case of the recent Nepal quake, the way the two plates came to rest caused Mt. Everest to lose height! Subduction zones often become areas of heightened activity.
One of the most challenging things about earthquakes is the drama isn’t over after the “main” shock. After the initial devastation at the epicenter, the earth is still settling and reshuffling itself into place causing further shakes called aftershocks. Some can be quite severe, frequent, and go on for extended periods of time – even years. It’s what makes recovery in remote areas quite hard to manage. Buildings and infrastructure have become unstable and more susceptible to the rattling – even if it is of lesser magnitude.
So can we predict earthquakes? The most reliable answer is to say not definitively. There have been cases in China where monitoring set up in high-risk regions have recorded questionable activity and given officials time to evacuate. However, just as often a quake will come with no warning at all.
The earth is unpredictable. While we have become extremely knowledgeable over the years about where trouble zones are for earthquakes and volcanoes around the world, we still don’t have a full understanding of when devastating events may occur. Fortunately, there are scientists and researchers all over the globe studying the earth’s hotspots with a keen eye, and those who head into the devastation afterwards to gain clues that might help us create informed, reliable warnings in the future.
We hope you’ll find deeper answers in our playlist above, all about when the earth makes its moves.