It must be frustrating to be hit by a huge earthquake, and then have experts inform you that the "Big One" might still be coming. Yet that's part of life in Chile: Despite being rocked by a major temblor earlier this month, the country seems to have gotten off relatively easy this time. As one geophysicist said: "Could be tomorrow, could be in 50 years; we do not know when it's going to occur. But the key point here is that this magnitude-8.2 is not the large earthquake that we were expecting for this area."
That's because this part of the world has a massive amount of energy stored in constantly butting tectonic plates. In fact, it can claim ownership to the largest earthquake ever measured by modern equipment, the Great Chile Earthquake of May 22, 1960. That catastrophe left 2 million people homeless and killed others as far away as Hawaii and Japan with a towering tsunami. And over the decades South America's western coast has shaken and trembled like Jell-O under the force of numerous other quakes, which is the case for any place sited above shifting fault zones.
Thanks to the hard work of innumerable researchers and the U.S. Geological Survey, we can see all the hot spots for seismic activity in Chile and elsewhere since 1900. They've put together a gigantic map of quakes that measured above 5.5 magnitude, color and size-coded to indicate power and depth. What's instantly apparent is that the shaking sticks close to the various plate boundaries, depicted as yellow lines, as do volcanoes shown as yellow triangles. Here's the full key: