WHEN THE EARTH RUMBLES (IN SAN FRANCISCO)

My sister, Bridget, who has lived in San Francisco for over a year now, experienced her first earthquake yesterday morning. While thankfully this 6.0 earthquake didn't cause much more than a soft rumble in San Francisco, she informed me that the last earthquake of similar magnitude was in 1989, and it caused widespread damage to the city.

The devastation was largely located in parts of the city built on a landfill made during the city's reconstruction after the historically catastrophic earthquake in 1906. During strong earthquakes the soil in the landfill is susceptible to liquefaction. Building neighborhoods on such unpredictable foundations is unnerving and clearly not the best case scenario - but buildings in earthquake prone areas are typically constructed to withstand earthquakes, and recent developments in architectural engineering are even more promising.

The method which fascinates me the most is called the seismic invisibility cloak. The system's name is well suited, as buildings are made transparent to surface waves produced by an earthquake. Waves encounter 100 concentric, plastic rings beneath the buildings foundation, and as they enter the rings they are compressed into a bottleneck. They then zip beneath the foundation and exit the rings, where they resume their original speed and amplitude. Being both economical and feasible, this system has been installed beneath many older buildings - including city halls in San Francisco, Oakland and Los Angelas.

Other buildings are built to actually deform and then return back to their original shape. These contain Rocking Frames, which are engineered with steel frames, steel cables, and steel fuses. When an earthquake causes the frames to rock up and down, the energy is directed from the cables to several tooth-like fuses that gnash together. Even if the fuses fail, the frame stays intact. Once shaking subsides, the frames pull the building back to its original upright position.

So next time you're in San Francisco and the floor begins to rumble beneath you, don't panic. Likely the violent shaking means your building was designed so that the walls would not snap and crumble around you. Just follow this relevant guide to safety. (And maybe review these liquefaction maps before booking a place to stay.)

more on earthquakes:
the culprit behind California's many earthquakes
earthquakes 101
top 10 deadliest earthquakes in history
and because, why not?