White Island Drums

The timestamps shown at the top right of the seismograph drums shown below are the time when these images were 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.

RSAM (Real-time Seismic-Amplitude Measurement) and SSAM (Seismic Spectral-Amplitude Measurement) are techniques that permit volcano seismologists to evaluate the nature of seismicity at a volcano. They are able to recognize subtle shifts in frequency related to changing dynamics of magma or gas movement within the volcano, or the amount and style of volcanic tremor. They also show other noise like windy weather or traffic.