And of course, the earthquake energy source is many magnitudes larger and much, much further away, deep in the crust, with the wavefront already having passed through miles of solid rock. We measure blasts from at most a few hundred meters away.
And of course, the earthquake energy source is many magnitudes larger and much, much further away, deep in the crust, with the wavefront already having passed through miles of solid rock. We measure blasts from at most a few hundred meters away.
In an unbalanced wave, the earth is permanently displaced in a particular direction. We can measure that net displacement in a particular direction using an anti-derivative if the total average velocity is nonzero (if we included negative velocities around a given axis). Earthquakes, of course, tend to have nonzero net displacement, and thus an extremely biased velocity waveform along a particular axis.
So in fact, the soil beneath you vibrating back and forth at 1 to 5 inches per second is not fun. At 118 inches per second? Catastrophe.