Seismograph Drums
This image shows seismic activity during the last 24 hours at a station on Raoul Island.
The timestamp shown at the top right of the seismograph drum shown below is the time when this image was last refreshed. Each horizontal line (or trace) represents 30 minutes, each vertical line is spaced 1 minute apart; 24 hours of recording are displayed in total. The most recent signal is drawn at the bottom right hand corner of the drum. Then read the traces from right to left, bottom to top, to get from the most recent to the oldest signals. The trace will appear red if the signals are very large; this means they have been clipped to stop them overwriting too much of the surrounding image.
Raoul Island Volcano Drum
