Title: Reply to comment by M. Hagerty and S. Sherburn on ‘External modulation of volcanic activity’
Abstract: This reply is based on the re-evaluation of an original data set of spectral seismic amplitudes on short-period seismic stations on Ruapehu, New Zealand, recorded in 1990. While there is agreement that a diurnal peak in the tremor spectrum on Ruapehu is most probably caused by man-made noise, there is disagreement in how to treat time-series adequately in the presence of data gaps. It is demonstrated why Hagerty and Sherburn fail to detect peaks of spectral energy.