| Abstract: | The digitising system installed at the Chateau Observatory, in the North Island of New Zealand, to monitor Ruapehu and Ngauruhoe volcanoes is used to digitise the seismic records from three seismometers, and to calculate the power spectra of volcanic tremor in real-time, with the smoothed power spectra being recorded every 5 minutes on magnetic disk. The 5-minute averages are later processed to remove the effects of earthquakes and interference before hourly averages are calculated. This system has a better dynamic range than visual chart records, and analysis of the data requires much less labour. |
