Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit


Our understanding of the earthquake process requires detailed insights into how the tectonic stresses are accumulated and released on seismogenic faults. We derive the full vector displacement field due to the Bam, Iran, earthquake of moment magnitude 6.5 using radar data from the Envisat satellite of the European Space Agency. Analysis of surface deformation indicates that most of the seismic moment release along the 20-km-long strike-slip rupture occurred at a shallow depth of 4–5 km, yet the rupture did not break the surface. The Bam event may therefore represent an end-member case of the ‘shallow slip deficit’ model, which postulates that coseismic slip in the uppermost crust is systematically less than that at seismogenic depths (4–10 km). The InSAR-derived surface displacement data from the Bam and other large shallow earthquakes suggest that the uppermost section of the seismogenic crust around young and developing faults may undergo a distributed failure in the interseismic period, thereby accumulating little elastic strain.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Coseismic deformation caused by the Bam earthquake as imaged by the Envisat ASAR data.
Figure 2: Displacements along a profile A–A′ perpendicular to the Bam earthquake rupture (Fig. 1).
Figure 3: Distribution of seismic potency averaged along the fault length L.


  1. 1

    Massonnet, D. et al. The displacement field of the Landers earthquake mapped by radar interferometry. Nature 364, 138–142 (1993)

    ADS  Article  Google Scholar 

  2. 2

    Peltzer, G., Crampe, F. & King, G. Evidence of nonlinear elasticity of the crust from the M w 7.6 Manyi (Tibet) earthquake. Science 286, 272–276 (1998)

    Article  Google Scholar 

  3. 3

    Simons, M., Fialko, Y. & Rivera, L. Coseismic deformation from the 1999 M w 7.1 Hector Mine, California, earthquake, as inferred from InSAR and GPS observations. Bull. Seismol. Soc. Am. 92, 1390–1402 (2002)

    Article  Google Scholar 

  4. 4

    Fialko, Y. Probing the mechanical properties of seismically active crust with space geodesy: Study of the co-seismic deformation due to the 1992 M w 7.3 Landers (southern California) earthquake. J. Geophys. Res. 109, doi:10.1029/2003JB002756 (2004)

    ADS  Google Scholar 

  5. 5

    Feigl, K. L. et al. Estimating slip distribution for the Izmit mainshock from coseismic GPS, ERS-1, RADARSAT and SPOT measurements. Bull. Seismol. Soc. Am. 92, 138–160 (2002)

    Article  Google Scholar 

  6. 6

    Cakir, Z. et al. Coseismic and early post-seismic slip associated with the 1999 Izmit earthquake (Turkey), from SAR interferometry and tectonic field observations. Geophys. J. Int. 155, 93–110 (2003)

    ADS  Article  Google Scholar 

  7. 7

    Jonsson, S., Zebker, H., Segall, P. & Amelung, F. Fault slip distribution of the 1999 M w 7.1 Hector Mine, California, earthquake, estimated from satellite radar and GPS measurements. Bull. Seismol. Soc. Am. 92, 1377–1389 (2002)

    Article  Google Scholar 

  8. 8

    Fialko, Y., Simons, M. & Agnew, D. The complete (3-D) surface displacement field in the epicentral area of the 1999 M w 7.1 Hector Mine earthquake, southern California, from space geodetic observations. Geophys. Res. Lett. 28, 3063–3066 (2001)

    ADS  Article  Google Scholar 

  9. 9

    Tse, S. T. & Rice, J. R. Crustal earthquake instability in relation to the depth variation of frictional slip properties. J. Geophys. Res. 91, 9452–9472 (1986)

    ADS  Article  Google Scholar 

  10. 10

    Thatcher, W. Nonlinear strain build-up and the earthquake cycle on the San Andreas fault. J. Geophys. Res. 88, 5893–5902 (1983)

    ADS  Article  Google Scholar 

  11. 11

    Savage, J. & Svarc, J. Postseismic deformation associated with the 1992 M w = 7.3 Landers earthquake, southern California. J. Geophys. Res. 102, 7565–7577 (1997)

    ADS  Article  Google Scholar 

  12. 12

    Manning, C. & Ingebritsen, S. Permeability of the continental crust: Implications of geothermal data and metamorphic systems. Rev. Geophys. 37, 127–150 (1999)

    ADS  Article  Google Scholar 

  13. 13

    Byerlee, J. Friction of rock. Pure Appl. Geophys. 116, 615–626 (1978)

    ADS  Article  Google Scholar 

  14. 14

    Marone, C. Laboratory-derived friction laws and their application to seismic faulting. Annu. Rev. Earth Planet. Sci. 26, 643–696 (1998)

    ADS  CAS  Article  Google Scholar 

  15. 15

    Lyons, S. & Sandwell, D. Fault creep along the southern San Andreas from interferometric synthetic aperture radar, permanent scatterers, and stacking. J. Geophys. Res. 108, doi:10:1029/2002JB001831 (2003)

  16. 16

    Tatar, M. et al. Aftershocks study of the 26 December 2003 Bam earthquake. J. Seismol. Earthquake Eng. (in the press)

  17. 17

    Rosen, P. et al. Synthetic aperture radar interferometry. Proc. IEEE 88, 333–382 (2000)

    Article  Google Scholar 

  18. 18

    Michel, R. & Avouac, J.-P. Measuring ground displacements from SAR amplitude images: Application to the Landers earthquake. Geophys. Res. Lett. 26, 875–878 (1999)

    ADS  Article  Google Scholar 

  19. 19

    Peltzer, G., Rosen, P., Rogez, F. & Hudnut, K. Poroelastic rebound along the Landers 1992 earthquake surface rupture. J. Geophys. Res. 103, 30131–30145 (1998)

    ADS  Article  Google Scholar 

  20. 20

    Jacobs, A., Sandwell, D., Fialko, Y. & Sichoix, L. The 1999 (M w 7.1) Hector Mine, California, earthquake: Near-field postseismic deformation from ERS interferometry. Bull. Seismol. Soc. Am. 92, 1433–1442 (2002)

    Article  Google Scholar 

  21. 21

    Fialko, Y. Evidence of fluid-filled upper crust from observations of post-seismic deformation due to the 1992 M w 7.3 Landers earthquatek. J. Geophys. Res. 109, doi:10.1029/2004JB002985 (2004)

  22. 22

    Chinnery, M. A. The deformation of the ground around surface faults. Bull. Seismol. Soc. Am. 51, 355–372 (1961)

    Google Scholar 

  23. 23

    Talebian, M. et al. The 2003 Bam (Iran) earthquake: Rupture of a blind strike-slip fault. Geophys. Res. Lett. 31, L11611, doi:10.1029/2004GL020058 (2004)

    ADS  Article  Google Scholar 

  24. 24

    Heaton, T. Evidence for and implications of self-healing pulses of slip in earthquake rupture. Phys. Earth Planet. Inter. 64, 1–20 (1990)

    ADS  Article  Google Scholar 

  25. 25

    Boatwright, J. Spectral theory for circular seismic sources—simple estimates of source dimension, dynamic stress drop, and radiated seismic energy. Bull. Seismol. Soc. Am. 70, 1–27 (1980)

    Google Scholar 

  26. 26

    Savage, J. & Lisowski, M. Inferred depth of creep on the Hayward fault, central California. J. Geophys. Res. 98, 787–793 (1993)

    ADS  Article  Google Scholar 

  27. 27

    Delouis, B., Giardini, D., Lundgren, P. & Salichon, J. Joint inversion of InSAR, GPS, teleseismic, and strong-motion data for the spatial and temporal distribution of earthquake slip: Application to the 1999 Izmit mainshock. Bull. Seismol. Soc. Am. 92, 278–299 (2002)

    Article  Google Scholar 

  28. 28

    Okada, Y. Surface deformation due to shear and tensile faults in a half-space. Bull. Seismol. Soc. Am. 75, 1135–1154 (1985)

    Google Scholar 

  29. 29

    Wang, R., Martin, F. & Roth, F. Computation of deformation induced by earthquakes in a multi-layered elastic crust—FORTRAN programs EDGRN/EDCMP. Comp. Geosci. 29, 195–207 (2003)

    Article  Google Scholar 

  30. 30

    Marone, C., Scholz, C. & Bilham, R. On the mechanics of earthquake afterslip. J. Geophys. Res. 96, 8441–8452 (1991)

    ADS  Article  Google Scholar 

  31. 31

    Williams, P., McGill, S., Sieh, K., Allen, C. & Louie, J. Triggered slip along the San Andreas fault after the 8 July 1986 North Palm-Springs earthquake. Bull. Seismol. Soc. Am. 78, 1112–1122 (1988)

    Google Scholar 

  32. 32

    Bilham, R. Surface slip subsequent to the 24 November 1987 Superstition Hills, California, earthquake monitored by digital creepmeters. Bull. Seismol. Soc. Am. 79, 424–450 (1989)

    Google Scholar 

  33. 33

    Sandwell, D., Sichoix, L., Agnew, D., Bock, Y. & Minster, J.-B. Near real-time radar interferometry of the M w 7.1 Hector Mine Earthquake. Geophys. Res. Lett. 27, 3101–3104 (2000)

    ADS  Article  Google Scholar 

  34. 34

    Sharp, R., Rymer, M. & Lienkaemper, J. Surface displacement on the Imperial and Superstition Hills faults triggered by the Westmoreland, California, earthquake of 26 April 1981. Bull. Seismol. Soc. Am. 76, 949–965 (1986)

    Google Scholar 

  35. 35

    Bürgmann, R. et al. Earthquake potential along the northern Hayward fault, California. Science 289, 1178–1182 (2000)

    ADS  Article  Google Scholar 

  36. 36

    Peltzer, G., Crampe, F., Hensley, S. & Rosen, P. Transient strain accumulation and fault interaction in the Eastern California shear zone. Geology 29, 975–978 (2001)

    ADS  Article  Google Scholar 

  37. 37

    Lettis, W., Wells, D. & Baldwin, J. Empirical observations regarding reverse earthquakes, blind thrust faults, and quaternary deformation: Are blind thrust faults truly blind? Bull. Seismol. Soc. Am. 87, 1171–1198 (1997)

    Google Scholar 

  38. 38

    Dolan, J., Christofferson, S. & Shaw, J. Recognition of paleoearthquakes on the Puente Hills blind thrust fault, California. Science 300, 115–118 (2003)

    ADS  CAS  Article  Google Scholar 

  39. 39

    Sylvester, A. Strike-slip faults. Geol. Soc. Am. Bull. 100, 1666–1703 (1988)

    ADS  Article  Google Scholar 

  40. 40

    Ben-Zion, Y. et al. A shallow fault-zone structure illuminated by trapped waves in the Karadere-Duzce branch of the North Anatolian Fault, western Turkey. Geophys. J. Int. 152, 699–717 (2003)

    ADS  Article  Google Scholar 

  41. 41

    Fialko, Y. et al. Deformation on nearby faults induced by the 1999 Hector Mine earthquake. Science 297, 1858–1862 (2002)

    ADS  CAS  Article  Google Scholar 

  42. 42

    Hickman, S. & Zoback, M. Stress orientations and magnitudes in the SAFOD pilot hole. Geophys. Res. Lett. 31, L15S12, doi:10.1029/2004GL20043 (2004)

    Article  Google Scholar 

  43. 43

    Sieh, K. E. & Jahns, R. H. Holocene activity of the San Andreas fault at Wallace Creek, California. Geol. Soc. Am. Bull. 95, 883–896 (1984)

    ADS  Article  Google Scholar 

  44. 44

    Oskin, M. & Iriondo, A. Large-magnitude transient strain accumulation on the Blackwater fault, Eastern California shear zone. Geology 32, 313–316 (2004)

    ADS  Article  Google Scholar 

  45. 45

    Rosen, P., Hensley, S., Peltzer, G. & Simons, M. Updated repeat orbit interferometry package released. Eos 85, 47 (2003)

    ADS  Article  Google Scholar 

  46. 46

    Scharoo, R. & Visser, P. Precise orbit determination and gravity field improvement for the ERS satellites. J. Geophys. Res. 103, 8113–8127 (1998)

    ADS  Article  Google Scholar 

  47. 47

    Farr, T. & Kobrick, M. Shuttle Radar Topography Mission produces a wealth of data. AGU Eos 81, 583–585 (2000)

    ADS  Article  Google Scholar 

Download references


We thank R. Bürgmann for comments. This work was supported by the National Science Foundation and the Southern California Earthquake Center. Original Envisat ASAR data are copyright of the European Space Agency, acquired under CAT-1 research category. Aftershock locations were provided by M. Tatar, and coordinates of the geologically mapped faults by M. Heydari. P.R. conducted his work at JPL/Caltech, under contract with NASA.

Author information



Corresponding author

Correspondence to Yuri Fialko.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Figure 1

Shaded relief map of the epicentral area of the Bam earthquake. (JPG 41 kb)

Supplementary Figure 2

Slip distribution from the inversion of the Envisat ASAR data for the layered elastic half-space model. (JPG 24 kb)

Supplementary Figure 3

Sub-sampled ASAR data used in the inversion; best-fitting models; and residuals after subtracting the best-fitting models from the data. (JPG 80 kb)

Supplementary Legends

Legends for Supplementary Figs 1-3. (DOC 19 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Fialko, Y., Sandwell, D., Simons, M. et al. Three-dimensional deformation caused by the Bam, Iran, earthquake and the origin of shallow slip deficit. Nature 435, 295–299 (2005).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Sign up for the Nature Briefing newsletter for a daily update on COVID-19 science.
Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing