Electronic Supplement to
Detection of Instrument Gain Problems Based on Body-Wave Polarization: Application to the Hi-Net Array

by Sunyoung Park and Miaki Ishii

This electronic supplement contains a table and two figures. Table S1 has the complete list of stations that are detected with gain issues in this study. For each station, problematic time periods with corresponding criterion and amplitude ratio are reported. Figures S1 and S2 describe cases where the gain issues are identified by calibration pulse data but not by our analysis and vice versa.


Table

Table S1. List of stations with problematic time periods associated with each criterion (I)–(IV) and the cluster analysis (C). Time periods are defined by the start and end date of consecutive problematic measurements. Amplitude ratios between horizontal-to-vertical (H/V) and east-west to north-south (EW/NS) components are calculated by comparing the median of measured angles during the time period to that of normal period of the station. For the stations with gain problem in entire period, median of normal values of all High-Sensitivity Seismograph Network (Hi-net) stations has been used (colored in red). Both H/V and EW/NS ratios are shown for the detections based on the cluster analysis.


Figures

Figure S1. Measured angles (circles) corresponding to (a) θP, (b) θS, and (c) ϕP at station SDMH. The data are shown as a function of time from 2004 to April 2016 and each circle corresponds to a teleseismic earthquake. Blue circles are those identified to have instrument issue in the horizontal components in the first step, and black circles belong to time periods without instrument issues. Magenta circles represent those identified to have instrument issue in both vertical and horizontal components, that is, corresponding to the criteria (I) or (II) and (III) or (IV) at the same time. Gray lines with plus signs are amplitude ratio (a) between horizontal and vertical and (c) between the two horizontal components obtained using the Hi-net calibration peaks. The vertical axes labels on the right side denote vertical (V), EW, NS, and the average of the two horizontal (H) amplitudes. The amplitude ratios are plotted in log scales. Based on the calibration pulse data, the H/V amplitude ratios from the late 2007 are significantly high, but the measured angles do not exhibit such abnormality.

Figure S2. Same as Figure S1, except that it is for station SSWH. The measured P-horizontal angles ϕP are nearly 90° from early 2006, but the calibration pulse data do not show corresponding feature in the EW to NS amplitude ratios.

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