Additional file 1 of Stress drops of intermediate-depth intraslab earthquakes beneath Tohoku, northern Japan
Creators: name: Kita, Saeko
name: Shiina, Takahiro
name: Houston, Heidi
name: Shiomi, Katsuhiko
Publisher: name: figshare
Year: 2024
Subjects: subject: Geophysics
subject: FOS: Earth and related environmental sciences

description: Additional file 1: Figure S1: Histogram showing the number of pairs per event for events whose corner frequencies were estimated in this study. Figure S2: (a-d) Estimation of corner frequencies for one earthquake (origin time: 25 April 2003 16:27:48; depth: 72.87 km; location: 38.6488°N, 141.3690°E; Magnitude: 2.0). (a) Estimation of corner frequencies of one pair of events. (b) Estimation of corner frequencies for a pair of events. (c) Estimation of corner frequencies of a pair of events. (d) (Left) Locations of all event pairs used in the estimation. (Right) Estimated corner frequencies. Figure S3: (a) Corner frequencies for events plotted against seismic moment estimated in this study. Black bars show the standard deviations in the estimation for the corner frequencies. Other explanations are the same as Fig. 3a. (b) Estimated stress drops of all intraslab earthquakes plotted against depth beneath Tohoku region at depths of 70 to 200 km. Gray bars show estimation the standard deviations of stress drops based on standard deviations in the estimation of the corner frequencies. Other explanations are the same as Fig. 3b. (c) and (d) Estimated stress drop at depths of 70–180 km plotted against depth for (a) events in the OC and (b) events in the OM. Gray bars indicate estimation errors of stress drops based on the standard deviations in the estimation of the corner frequencies. Other explanations are the same as Figs. 4a and 4b. Figure S4: Estimated stress drop at depths of 70–170 km plotted against depth for (a) events in the OC and (b) events in the OM. In Figures S4a and S4b, color-coded open squares denote the median stress drops at depths of 70–90 km, 90–110 km, 110–130 km, 130–150 km and 150–180 km. Other explanations are the same in Figs. 4a and 4b. Figure S5: (a) Estimated stress drop of each event against normal distance from the upper plate interface beneath Tohoku excluding aftershocks of the 2003 M 7.1 Miyagi intraslab earthquake. (b) that including the aftershocks (the same as Fig. 6a in the main manuscript). Explanations for symbols are the same in Fig. 6a. Figure S6: (a-b) Estimated stress drop at depths of 70–170 km plotted against depth for (a) events (2.0 &lt; Magnitude &lt; 5.0) in the OC and (b) events in the OM using a constant S-wave velocity of 4.6 (km/s). In Figures S6a and S6b, color-coded open squares denote the median stress drops at depths of 70–90 km, 90–110 km, 110–130 km, 130–150 km and 150–180 km. Other explanations are the same in Figs. 4a and 4b. (c-d) Estimated stress drop at depths of 70–170 km plotted against depth for (c) events (2.0 &lt; Magnitude &lt; 3.0) in the OC and (d) events in the OM. (e–f) Estimated stress drop at depths of 70–170 km plotted against depth for (e) events (3.0 &lt; Magnitude &lt; 4.0) in the OC and (f) events in the OM. Figure S7: (a) Estimated stress drop at depths of 70–170 km plotted against depth for events in the OM (a) using the 1D structure by Hasegawa et al. (1978) and (b) that using the JMA 1D velocity structure model (the same as Fig. 4b in the main manuscript). Explanations for symbols are the same in Fig. 4b. Figure S8: (a) Estimated stress drop at depths of 70–170 km plotted against depth for events in the OC (a) before the M 9.0 Tohoku earthquake and (b) after it. Explanations for symbols are the same in Fig. 4a. Table S1: Median stress drops of all events in the Pacific slab beneath Tohoku at depths of 70–200 km (as shown in Fig. 3b). Table S2: Median stress drops of upper-plane, interplane and lower plane in the Pacific slab beneath Tohoku at depths of 70–180 km, as shown in Figures S4. Table S3: Median stress drops of upper-plane, interplane and lower plane in the Pacific slab beneath Hokkaido at depths of 70–180 km, as shown in Fig. 7b.