An anonymous reader writes: Seismometers have been deployed throughout the world. Scientists need a big web of them to gather data about earthquakes, and the network has expanded widely over the past 60 years. As it turns out, seismometers are pretty good at picking up vibrations from things that aren't earthquakes. A team of researchers scouring logs from 2006 were able to find clear evidence of the explosion of a munitions depot in Iraq. And that's not all: "The team, led by Ghassan Aleqabi of Washington University in St. Louis, carefully analyzed each wiggle on the seismograph and discovered it could identify a number of different things. The firing of a mortar, for example, was identifiable along with the explosion when the shell landed. Car bomb explosions also stood out, although the bouncing of the shockwave off surrounding buildings made each one a bit different. The team could even identify signals from drones and helicopters and figure out if they were approaching or moving away based on the Doppler shift."