This electronic supplement contains three figures showing the number of observations by station name and earthquake ID (Fig. S1), a decomposition of the regression biases using the CRUST1.0 global velocity model (Laske et al., 2013; Fig. S2), and an example of dynamic strains estimated by triangulation of collocated Global Positioning System (GPS)–strong-motion instruments for the 2011 M 9 Tohoku-Oki earthquake (Fig. S3).
Figure S1. Observational groupings. The number of peak strain observations for each (a) station and (b) earthquake. Note the differences in scales and the scale break in (b).
Figure S2. CRUST1.0 composition of regression biases. Decomposition of dynamic-strain regression biases from equation (8) in the main article based on the CRUST1.0 global velocity model (Laske et al., 2013) for (a) source–path biases and (b) site–station biases. Variations are shown with boxplots, which encode the median (thick bar), interquartile range (box), and limits of the given biases. Boxplots are shown for (1) crustal types, (2) S-wave velocities in the shallow crust (km/s), (3) S-wave velocities in the shallow sedimentary layer (km/s), and (4) the log ratio of S-wave velocities.
Figure S3. Demonstration of GPS-based strain estimates. Example of the transformation of triangulated GPS–strong-motion measurements into strain. (a) Horizontal GPS time series overlaid on acceleration time series for each node in the given subnetwork, T109 (see map in b). Time scales are in seconds from origin time. (b) Map of station triangulations with subnetwork T109 highlighted. (c) Time series of principal strains derived from GPS and acceleration data. The reversal in principal strains prior to P-wave arrivals is due to instability in the inversion owing to low signal-to-noise ratio levels. (d) Time series of root mean square (rms) principal strain showing peak value.
The CRUST1.0 model is available at http://igppweb.ucsd.edu/~gabi/crust1.html (last accessed December 2016).
Laske, G., G. Masters, Z. Ma, and M. Pasyanos (2013). Update on CRUST1.0—A 1-degree global model of Earth’s crust, Geophys. Res. Abstr. 15, 2658.
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