Electronic Supplement to
A Long-term Forecast of Shallow Seismicity Based on the Global Strain Rate Map

by P. Bird, C. Kreemer, and W. E. Holt


In this supplement we provide the gridded SHIFT/GSRM forecast for two representative threshold magnitudes, and also the files necessary to reproduce the computation, or to compute similar forecast maps for other threshold magnitudes.

Gridded SHIFT/GSRM forecasts:

SHIFT_GSRM_forecast_grids.zip is a compressed archive (<2 MB) which contains two forecast grid files (each 64 MB when uncompressed):
GSRM_SHIFT_0p6x0p5flat_4factors_m5p66.grd is the forecast for threshold moment-magnitude 5.66;
GSRM_SHIFT_0p6x0p5flat_4factors_m8.grd is the forecast for threshold moment-magnitude 8.00.
The .grd file format is documented online at: http://peterbird.name/guide/grd_format.htm.

Files needed to compute SHIFT/GSRM forecasts for other threshold magnitudes:

SHIFT_GSRM.f90 is Fortran 90 source code for the program.

tectonic_areas.dat defines quadrilaterals (in longitude/latitude space) which collectively make up each of the four deformation regimes defined by Kreemer et al. (2002). The following abbreviations are used: C = Continental, O = diffuse Oceanic, R = Ridge-transform, and S = Subduction. Each quadrilateral is represented by 5 corner points (the last being the same as the first), which are quoted in counterclockwise order. Longitudes are positive to the East, and latitudes are positive to the North. Areas not covered by any of these quadrilaterals are Intraplate areas.

average_strain.dat is version 1.2 (May 2004) of the Global Strain Rate Map, described by Kreemer et al. (2003). Specifically, this table lists horizontal-plane (three-component) strain-rate tensors which are average values, stated at the centers, of 0.6-degree by 0.5-degree longitude/latitude rectangles forming a regular grid. Rectangles not described in this file are intraplate regions with zero assumed strain-rate.

References Cited:

Kreemer, C., W. E. Holt, and A. J. Haines (2002) The global moment rate distribution within plate boundary zones. In: Plate Boundary Zones, edited by S. Stein and J. T. Freymueller, Geodynamics Series 30, American Geophysical Union, Washington, 173-190.

Kreemer, C., W. E. Holt, and A. J. Haines (2003) An integrated global model of present-day plate motions and plate boundary deformation, Geophys. J. Int. 154, 8-34.

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