The 1999 (Mw 7.1) Hector Mine, California, Earthquake: Near-Field Postseismic Deformation from ERS Interferometry

Interferometric synthetic aperture radar (InSAR) data over the area of the Hector Mine earthquake (Mw 7.1, 16 October 1999) reveal postseismic defor- mation of several centimeters over a spatial scale of 0.5 to 50 km. We analyzed seven SAR acquisitions to form interferograms over four time periods after the event. The main deformations seen in the line-of-sight (LOS) displacement maps are a region of subsidence (60 mm LOS increase) on the northern end of the fault, a region of uplift (45 mm LOS decrease) located to the northeast of the primary fault bend, and a linear trough running along the main rupture having a depth of up to 15 mm and a width of about 2 km. We correlate these features with a double left-bending, right- lateral, strike-slip fault that exhibits contraction on the restraining side and extension along the releasing side of the fault bends. The temporal variations in the near-fault postseismic deformation are consistent with a characteristic time scale of 135 42 or 25 days, which is similar to the relaxation times following the 1992 Landers earthquake. High gradients in the LOS displacements occur on the fault trace, con- sistent with afterslip on the earthquake rupture. We derive an afterslip model by inverting the LOS data from both the ascending and descending orbits. Our model indicates that much of the afterslip occurs at depths of less than 3 to 4 km.

[1]  Charles Werner,et al.  On the derivation of coseismic displacement fields using differential radar interferometry: The Landers earthquake , 1994 .

[2]  Kenneth W. Hudnut,et al.  Preliminary Report on the 16 October 1999 M 7.1 Hector Mine, California, Earthquake , 2000 .

[3]  E. Hauksson,et al.  The 1999 Mw 7.1 Hector Mine, California, Earthquake Sequence: Complex Conjugate Strike-Slip Faulting , 2002 .

[4]  Michael Church,et al.  On the misuse of regression in earth science , 1977 .

[5]  P. Rosen,et al.  On the derivation of coseismic displacement fields using differential radar interferometry: The Landers earthquake , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[6]  D. Agnew,et al.  The complete (3‐D) surface displacement field in the epicentral area of the 1999 MW7.1 Hector Mine Earthquake, California, from space geodetic observations , 2001 .

[7]  Didier Massonnet,et al.  Detection of postseismic fault-zone collapse following the Landers earthquake , 1996, Nature.

[8]  E. J. Price,et al.  Coseismic and postseismic deformations associated with the 1992 Landers, California, earthquake measured by synthetic aperture radar interferometry , 1999 .

[9]  William A. Bryant,et al.  Primary Surface Rupture Associated with the Mw 7.1 16 October 1999 Hector Mine Earthquake, San Bernardino County, California , 2002 .

[10]  A. Treiman,et al.  Primary Surface Rupture Associated with the M w 7 . 1 16 October , 2002 .

[11]  P. Visser,et al.  Precise orbit determination and gravity field improvement for the ERS satellites , 1998 .

[12]  Kanamori,et al.  Viscoelastic flow in the lower crust after the 1992 landers, california, earthquake , 1998, Science.

[13]  Yehuda Bock,et al.  Postseismic deformation following the Landers earthquake, California, 28 June 1992 , 1994, Bulletin of the Seismological Society of America.

[14]  L. Rivera,et al.  Coseismic Deformation from the 1999 Mw 7.1 Hector Mine, California, Earthquake as Inferred from InSAR and GPS Observations , 2002 .

[15]  F. Pollitz,et al.  Mantle Flow Beneath a Continental Strike-Slip Fault: Postseismic Deformation After the 1999 Hector Mine Earthquake , 2001, Science.

[16]  J. C. Crowell.  Origin of Late Cenozoic Basins in Southern California: ABSTRACT , 1973 .

[17]  David T. Sandwell,et al.  The 1999 Hector Mine Earthquake, Southern California: Vector Near-Field Displacements from ERS InSAR , 2002 .

[18]  Duncan Carr Agnew,et al.  Coseismic Displacements from the Hector Mine, California, Earthquake: Results from Survey-Mode Global Positioning System Measurements , 2002 .

[19]  George H. Davis,et al.  Structural geology of rocks and regions , 1984 .

[20]  C. Werner,et al.  Satellite radar interferometry: Two-dimensional phase unwrapping , 1988 .

[21]  Fuk K. Li,et al.  Synthetic aperture radar interferometry , 2000, Proceedings of the IEEE.

[22]  Yehuda Bock,et al.  Near real‐time radar interferometry of the Mw 7.1 Hector Mine Earthquake , 2000 .

[23]  T. W. Dibblee,et al.  Geologic map of the Lavic quadrangle, San Bernardino County, California , 1966 .

[24]  James C. Savage,et al.  Postseismic deformation associated with the 1992 M ω=7.3 Landers earthquake, southern California , 1997 .

[25]  Kenneth W. Hudnut,et al.  Poroelastic rebound along the Landers 1992 earthquake surface rupture , 1998 .

[26]  Paul Rosen,et al.  Postseismic Rebound in Fault Step-Overs Caused by Pore Fluid Flow , 1996, Science.

[27]  Roy K. Dokka,et al.  Role of the Eastern California Shear Zone in accommodating Pacific‐North American Plate motion , 1990 .

[28]  Michael B. Heflin,et al.  The coseismic geodetic signature of the 1999 Hector Mine earthquake , 2000 .

[29]  K. Feigl,et al.  Radar interferometry and its application to changes in the Earth's surface , 1998 .

[30]  K. Feigl,et al.  Radar interferometric mapping of deformation in the year after the Landers earthquake , 1994, Nature.

[31]  Duncan Carr Agnew,et al.  Early Postseismic Deformation from the 16 October 1999 Mw 7.1 Hector Mine, California, Earthquake as Measured by Survey-Mode GPS , 2002 .

[32]  K. Feigl,et al.  The displacement field of the Landers earthquake mapped by radar interferometry , 1993, Nature.

[33]  Ian Parsons,et al.  Surface deformation due to shear and tensile faults in a half-space , 1986 .

[34]  J. Haldane,et al.  Organic correlation and allometry. , 1950, Biometrika.

[35]  Kenneth W. Hudnut,et al.  Southern California Permanent GPS Geodetic Array: Continuous measurements of regional crustal deformation between the 1992 Landers and 1994 Northridge earthquakes , 1997 .