Tanvi Misra is a staff writer for CityLab covering immigrant communities, housing, economic inequality, and culture. She also authors Navigator, a weekly newsletter for urban explorers (subscribe here). Her work also appears in The Atlantic, NPR, and BBC.
And it's not just the cities above a fault line that move as a result of the tectonic rupture.
Ten feet sounds quite dramatic, but for an earthquake of this magnitude, this sort of shift over the fault is pretty typical, says Yale seismologist Maureen Long. She explains that the magnitude of an earthquake is proportional to the area of the fault that ruptures times the amount of slip on the fault.
In the case of Kathmandu, the tectonic plate under the city shifted southwards 10 feet over another plate along an ancient Himalayan fault line, releasing a seismic shock wave with the strength of "more than 20 thermonuclear weapons," according to the Wall Street Journal.
Check out this CCTV video of how violently the waves resulting from the slip shook the surface:
Beyond the damage to buildings and infrastructure, you can't really see the outward signs of this seismic displacement (unless the fault line intersects the surface, which is not the case in Kathmandu). It's also unclear if the shift is enough to require adjustments on high-precision world maps, the AFP notes. But that doesn't mean it's inconsequential.
Long says it can be revealing to compare shifts that occur during an earthquake with the slower tectonic movements that occur during resting periods. For example, the 8.8 magnitude quake that moved Maule, Chile, 10 feet in 2010, provided much fodder for geoscientists to study the how continental and oceanic tectonic plates moved.
In some senses, these movements impact all of us. A 2013 GPS analysis of the some of the biggest earthquakes of the 21st century revealed that they can cause geographic shifts far away from where the fault ruptures. The 2004 earthquake off the coast of Sumatra, which measured 9.1 and caused the horrific Tsunami in the Indian Ocean, produced movements as far as Africa, Arabia, the eastern half of Asia, and the Americas. Geologist Chris Rowan explained in a blog post from 2013:
If you leave a GPS receiver in a fixed location for days, months and years, it is precise enough to measure motions on the millimetre scale, allowing us to track strain building up across active faults, and even the incremental drift of the tectonic plates themselves across the Earth’s surface. But on the 26th December 2004, [GPS] stations across a sizeable slice of the Earth’s surface suddenly found themselves being jerked around a bit more rapidly. Basically, outside of western Europe and the Arctic Circle, pretty much the entire surface of the planet has been shifted at least a millimetre or two by an earthquake since the turn of the millennium.