There was a small earthquake in northern England on Tuesday. Barry Rowlingson felt the quake (it rattled the photographs on his wall), but didn't know how big of a quake it was because he didn't know how close he was to the epicentre. The British Geological Survey hadn't yet announced the quake, but did give access to seismograph readings, which indeed featured spikes marking the earthquake. So Barry read the times of the spikes from the charts, did a little triangulation based on the speed of wave propagation, crunched the numbers in R, and came up with this location for the epicentre (in blue):

The actual epicentre, as calculated by the USGS, is marked in red. Professional seismologists also use R to measure and locate earthquakes, but this is pretty good for a self-proclaimed quick-and-dirty calculation!

Barry Rowlingson's GeoSpatial Blog: Mapping The Kendal Mint Quake