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Figure S1. The background noise level (median absolute deviation) of daily-long
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continuous data for 4 HRSN stations that experienced network change versus days
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relative to the mainshock. The station and channel names are labeled on the right side.
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Figure S2. The availability of continuous data for all stations during the study period.
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The grey dashed line marks the origin time of the San Simeon mainshock. The station
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names are labeled on the left side.
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Figure S3. (a) The time differences between predicted P- and S-wave arrival times with
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the ones picked by NCEDC. The vertical solid and dashed lines mark the mean and two
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standard deviations of the time differences. (b) The red and blue histograms denote the
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MAD distribution for direct stacking and allowing one data point shift, respectively.
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Figure S4. The illustration of the one data point difference among the best correlating
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window of 4 different channels.
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Figure S5. The root mean square (RMS) of the relative P-wave arrival differences for all
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stations between one San Simeon aftershock and all templates events versus the distance
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along the SAF strike. The vertical dashed lines denote the region where most ‘false
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detections’ occurred.
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Figure S6. Comparison of waveforms between template 20040928192605 and
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20040928192610. The blue and red dashed lines denote the origin times of the two
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templates. The blue and red solid lines denote the predicted P- and S-wave arrival times
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of the two templates.
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Figure S7. (a)-(d) Frequency-magnitude plot in the whole study region, sub-region A, B,
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and C, respectively. Blue squares denote detected events. Red squares denote events
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listed in the NCSN catalog. Triangles denote obtained Mc using ZMAP. (e) Mc as a
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function of time in the whole study region.
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Figure S8. Frequency-magnitude plot in sub-region A for detected events before and after
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the San Simeon earthquake.
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Figure S9. (a) value in sub-region A versus days since the mainshock. Post-shock
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seismicity rate is measured in a 5-day time window, which moves forward by 2.5 days.
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Solid circles denote that pre-shock rate is measured prior to the San Simeon earthquake.
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Open diamonds denote that pre-shock rate is measured prior to the Md2.77 event. (b) the
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seismicity ratio in sub-region A versus days since the mainshock.
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Figure S10. The background shading denotes the Parkfield earthquake’s coseismic slip
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distribution [Murray and Langbein, 2006]. The blue denotes the epicenter of the
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Parkfield earthquake. The colored contour lines denote the static shear stress changes.
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Figure S11. (a) Cumulative number of events with M>1.5 in the NCSN catalog in
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sub-region A. (b) and (c) values and seismicity ratio versus cutoff magnitude with
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events listed in the NCSN catalog in sub-region A, respectively. Dots denote that
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background rate is measured prior to the San Simeon earthquake. Diamonds denote that
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background rate is measured prior to the abrupt jump in (a).
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References
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Murray, J., and J. Langbein (2006), Slip on the san andreas fault at parkfield, california, over two
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earthquake cycles, and the implications for seismic hazard, B Seismol Soc Am, 96(4B), S283-S303.