The Richter Scale uses a seismograph to measure seismic waves.
Consider a second seismograph reading, this time from a station at Puerto Princes.
The first Professor of Engineering was James Alfred Ewing, a native Dundonian who invented the continuous seismograph.
For local earthquakes it will move relatively to the pivoted balance weight like an ordinary bracket seismograph, and for very rapid motion it gives seismoscopic indications of slight tremors due to the switching of the outer end of the boom, which is necessarily somewhat flexible.
Figure 4. Locations of temporary seismograph stations (red squares) deployed around Manchester.