Supplementary Information

doi: 10.1038/nature08502 SUPPLEMENTARY INFORMATION

1. Sources for aftershock data in Fig. 1

a) Loma Prieta earthquake: http://neic.usgs.gov/neis/epic/ b) Dixie Valley earthquakes: http://www.seismo.unr.edu/Catalog/search.html c) New Madrid seismic zone: http://www.ceri.memphis.edu/seismic/catalogs/cat_nm.html http://www.eas.slu.edu/Earthquake_Center/earthquake_dos.html

2. Data, sources, and references for Fig. 2. Reference numbers are the same as in the paper, with the addition of ones listed below labeled “S.” Where rate data are not available, we use a nearby measurement. Rate uncertainties are difficult to precisely estimate, but are about 0.2 mm/yr for plate interior faults, 2 mm/yr for plate boundary zone faults, and 5 mm/yr for plate boundary faults. For the aftershock sequences constrained only for the upper or lower bounds, we arbitrarily plot the unconstrained upper and lower limits as 5,000 and 100 years, respectively, for intraplate earthquakes, and 500 and 50 years for events in broad plate boundary zones.

Location Date(y/m/d) Magnitude Duration (yr) Loading rate and (mm/yr) and references references Eastern Reelfoot, ~4000 BC ~M 7 < 6,000 (16) < 0.2 (14) central US New Madrid, 1811/12/16 Mw 7.2 > 197 < 0.2 (14) central US 1812/01/23 Mw 7.0 1812/02/07 Mw 7.4 Meers Fault, ~800 AD ~M 7 < 1,200 (17) < 0.2 (14) Oklahoma Charlevoix, 1663/02/05 M 7.0 > 346 0.7 (15) Canada Haicheng, China 1975/02/04 M 7.0 > 35 1 (S1, S2) Tangshan, China 1976/07/28 M 7.5 > 34 2 (S1) Hebgen Lake, 1959/08/17 M 7.3 > 50 3 (9) Montana Wasatch, Utah ~ 1375 AD ~ M 7 < 600 3 (9)

Nevada (and 1872/03/26 M > 7 ~ 100 (10) 4 (7) neighboring 1915/10/02 regions) 1932/12/20

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1954/12/16 Kern County, 1952/07/21 Mw 7.3 > 57 5 (8) California Landers, California 1992/06/28 Mw 7.3 8-12 (6) 12 (S3)

San Francisco, 1906/04/18 Mw 7.7 5-10 (3) 17 (S4) California Loma Prieta, 1989/10/17 Mw 6.9 3-10 (5,6) 17 (S4) California Kanto, Japan 1923/09/01 Ms 7.9 10-20 (S5) 30 (S6) Alaska 1964/03/27 Ms 8.4 5-10 (3) 53 (S7) Rat Island, Alaska 1965/02/04 Mw 8.7 4-8 (3) 72 (S7)

Additional References

S1. Shen, Z. K., Zhao, C., Yin, A. & Jackson, D. Contemporary crustal deformation in east Asia constrained by Global Positioning System measurements. J. Geophys. Res. 105, 5721-5734 (2000).

S2. Hsiao, L. Y. et al. Seismic reflection imaging of a major strike-slip fault zone in a rift system: Paleogene structure and evolution of the Tan-Lu fault system, Liaodong Bay, Bohai, offshore China, Amer. Assoc. Petroleum Geolog. Bull., 88, 71-97 (2004).

S3. Sauber, J., Thatcher, W., Solomon, S. C. & Lisowski, M. Geodetic slip rate for the eastern California shear zone and the recurrence time of Mojave desert earthquakes, Nature 367, 264 - 266 (1994). S4. Field, E. et al. The Uniform California Earthquake Rupture Forecast, Version 2, USGS Open File Report 2007- 1437 (2008). (http://pubs.usgs.gov/of/2007/1437/)

S5. Hamada, N., et al. A comprehensive study of aftershocks of the 1923 Kanto earthquake, J. Seismol. Soc. Japan, 54, 251-265 (2001).

S6. Seno, T., Stein, S. & Gripp, A. A model for the motion of the Philippine Sea Plate consistent with NUVEL-1 and geological data, J. Geophys. Res, 98, 17941-17948 (1993).

S7. DeMets, C., Gordon, R. G., Argus, D. F. & Stein, S., Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motion, Geophys. Res. Lett. 21, 2191-2194 (1994).