John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
A comprehensive look at which parts of the world have suffered historically large quakes.
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:
Now look at how much activity has occurred near the tectonic boundary off South America's coast over the past century. Those black-white circles indicate behemoth quakes, like the 1922 one on the Chilean-Argentinian border that killed hundreds, spawned a tidal wave, and sent earth shivers that were measurable up in San Francisco:
How has the United States fared over the decades? The eastern portion's been quite calm, aside from one medium-sized event in 2006 in the Gulf of Mexico that shook swimming pools in Florida. Out West is where things begin to get hairy, with a long line of seismic violence stretching from the Mexican border up to Alaska (and by association, down through Central America and across to Russia):
Southeast Asia's been absolutely pounded over history:
As has Japan – you can hardly see it under all these quake indicators:
Things have been relatively less exciting around the Mediterranean, although Italy, Greece, and Turkey have had their fair share of quakes and volcanoes:
You can download the full map here, though be warned that at 147 MB it will be a beast for your smartphone.
Maps courtesy of Tarr, A.C.; Villaseñor, Antonio; Furlong, K.P.; Rhea, Susan; and Benz, H.M.; U.S. Geological Survey Scientific Investigations