This electronic supplement contains added information and analysis done on the clusters that were referenced to in the main article. This includes figures of focal mechanism, maximum coulomb failure stress change, and percentage of events that experienced positive and negative shear stress, and an earthquake catalog.
Table S1 [Plain text comma-separated values; ~4 KB]. The strike, dip, and rake of both nodal planes of all the focal mechanisms found in the study area. It also includes the location and depth as well as the time of each event. The column headers are as follows: year, month, day, hour, minute, longitude (°), latitude (°), depth (km), magnitude, strike of nodal plane 1 (°), dip of nodal plane 1 (°), rake of nodal plane 1 (°), strike of nodal plane 2 (°), dip of nodal plane 2 (°), and rake of nodal plane 2 (°).
Table S2. List of the input source parameters for the three foreshocks.
Table S3. Combined ΔCFS (coulomb stress change) from foreshocks A–C on U.S. Geological Survey (USGS) and double-difference mainshock hypocenter location using different coefficients of friction.
Table S4. Number of events receiving positive ΔCFS from the mainshock, using different coefficients of friction.
Figure S1. The mean ΔCFS experienced between nodal plane 1 and nodal plane 2, on each event. (a,d,f) Map views of ΔCFS from each foreshock: source event (star) and the corresponding focal mechanism with the nodal plane used in model is indicated on it. The events that occur near the mainshock vicinity (diamonds) are called the “Sooner Lake cluster”; the events that occur in a cluster along the Labette fault (LF; squares) are referred to as the “Labette cluster”; and all other events are called “unclustered” (circles) (see legend). (b) Zoomed-in map view of the foreshock cluster of foreshock A with the black line showing fault trend. (c,e,g) Distance to mainshock versus time to mainshock for each event. Both X and Y axes are in log scale. The dashed line shows the time of the corresponding source event. All events that occurred prior to the source event are shown as white, indicating no ΔCFS values were calculated.
Figure S2. Percentage of events that experienced positive (triggered) and negative (not-triggered) ΔCFS on nodal plane 1, nodal plane 2, the mean of the two nodal values, and the maximum between the two nodal planes.
Figure S3. (a)–(c) Focal mechanisms for the three foreshocks obtained using HASH. North is denoted at the top of each focal mechanism with letter “N.” The triangles are polarity measurements that represent dilation, and circles represent polarity measurements that show compression. The letter “P” shows the orientation of the pressure axis, and “T” shows the orientation of the tension axis.
Figure S4. Map view of the mean ΔCFS from both nodal planes of the unrelocated aftershocks caused by the mainshock. Previously mapped faults are in black.
Figure S5. Percentage of events that experienced positive and negative shear stress on nodal plane 1, nodal plane 2, the mean of the two nodal values, and the maximum between the two nodal planes.
Figure S6. (a) The ΔCFS from foreshocks A–C on the rupture plane that was used to model the mainshock rupture. The black star represents the depth location of the double-difference relocation of the mainshock, with the USGS location being 0.3 km shallower. Each panel shows a different coefficient of friction used in the calculation and increases from left to right. (b) The ΔCFS from foreshocks A’s right-lateral rupture plane on the mainshocks rupture plane. It was calculated using a coefficient of friction of 0.4 and has a strike, dip, and rake of 58°/87°/−154°. (c) The ΔCFS from foreshocks A’s left-lateral rupture plane on the mainshocks rupture plane. It was calculated using a coefficient of friction of 0.4 and has a strike, dip, and rake of 326°/64°/−3°.
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