The figures in this electronic supplement show some additional information on the Japan University Seismic Network Earthquake Catalog of First-Motion Focal Mechanism (JUNEC FM^2), for example, distribution of focal mechanism solutions with the quality A, B, or C, and the distribution of focal mechanism solutions in each year. In addition, seismic velocity structure and temporal development of the observation station network used to determine focal mechanism solutions are shown. The distribution of focal mechanism solutions are well correlated with the station distribution, together with first-motion polarity report rate, as described in the text. Comparisons of focal mechanism solutions in this paper with those from other catalogs (i.e., first-motion focal mechanism solutions by the Japan Meteorological Agency [JMA] and moment tensor solutions by the National Research Institute for Earth Science and Disaster Prevention [NIED]), together with summarized information for other catalogs, are also shown; they are mostly similar for pairs of earthquakes in which the hypocenter locations are close to each other, although some show significantly discrepancies.
Figure S1. Seismic velocity structure 1983A (Hamada, 1984) used to determine the focal mechanism solutions.
Figure S2. Distribution of first-motion focal mechanism solutions. Blue, green, and red indicate the distributions of focal mechanism solutions with the quality of A, B or C, respectively.
Figure S3. (a) Distribution of first-motion focal mechanism solutions provided by JMA from January 1992 to December 2008. (b) The cumulative number (solid curves), and annual number of focal mechanism solutions (blue, score ≥ 90; green, 80 ≤ score < 90; red, score < 80). (c) Magnitude–frequency distribution of first-motion focal mechanism solutions by JMA (black). Blue, green, and red indicate the magnitude–frequency distribution of focal mechanism solutions for earthquakes with the score ≥ 90, 80 ≤ score < 90, and score < 80, respectively.
Figure S4. (a) Distribution of F-net focal mechanism solutions from January 1, 1997 to April 28, 2012 (e.g., Fukuyama et al., 1998). The symbols are the same as in Fig. S3. (b) Cumulative number (solid curves), and annual number of focal mechanism solutions (bar plot, blue; score ≥ 90, green; 80 ≤ score < 90, red; score < 80). (c) Magnitude–frequency distribution of F-net focal mechanism solutions (black). The blue, green, and red squares indicate the magnitude–frequency distribution of focal mechanism solutions with the score ≥ 90, 80 ≤ score < 90, and < 80, respectively.
Figure S5: (a)–(c), (d)–(f), (g)–(i), (j)–(l), (m)–(n). For each pair of maps, the left panels show temporal changes in the distributions of observation stations used to determine hypocenters and focal mechanism solutions and the right panels show the distributions of focal mechanism solutions in each year. The colors in the dilatation of the lower hemisphere indicate hypocentral depths. The number of focal mechanism solutions is also indicated.
Figure S6. (a) Comparison of focal mechanism solutions for pairs of earthquakes considered to be identical based on hypocenter information (i.e., origin time, longitude, latitude, depth, and magnitude) from January to June 1997. The two beach balls indicate the focal mechanism solutions (left ones with thin lines are by JMA; right ones with bold lines are determined in this study). The colors in the dilatation of the lower hemisphere indicate hypocentral depths. (b) Comparison of focal mechanism solutions for pairs of identical earthquakes from July to December 1997. Other symbols are the same as in (a).
Figure S7. (a) Comparison of focal mechanism solutions for pairs of earthquakes considered to be identical based on hypocenter information (i.e., origin time, longitude, latitude, depth, and magnitude) from January to June 1997. The two beach balls indicate the focal mechanism solutions (left ones with thin lines are from F-net moment tensor solutions provided by NIED; right ones with bold lines are determined in this study). The colors in the dilatation of the lower hemisphere indicate hypocentral depths. (b) Comparison of focal mechanism solutions for pairs of identical earthquakes from July to December 1997. Other symbols are the same as in (a).
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