A seismograph. The USGS says that during an earthquake, the base moves and the mass does not. The motion of the base with respect to the mass is commonly transformed into an electrical voltage. The electrical voltage is recorded on paper, magnetic tape, or another recording medium. Unless you’re out of paper. (U.S. Geological Survey)

So when the Earth moved in a large way last week, in not-too-distant Mineral, Va., and no Cub Scout dens were around, a number of USGS employees hustled into the lobby to see what the seismograph had to say.

And it was silent. The needle was moving, but no paper was in the printer to record its violent gyrations for immediate public consumption, USGS public affairs officer Anne-Berry Wade said.

The paper for the lobby seismograph is 16 inches wide and maybe 30 inches long, Wade said, and must be changed every 24 hours. “I’m guessing the person who’s responsible for changing that piece of paper,” Wade said, ”just hadn’t gotten around to changing it the day the earthquake hit.”

She noted that other seismographs at the USGS, and their printers, were working just fine when the 5.8 magnitude quake struck, and that the one in the lobby is “not used for scientific analysis.”

HT: S.F., Reston, Va.