Eastern California Shear Zone

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Eastern California Shear Zone
SCEC
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Eastern California Shear Zone

• Landers 1992
• Hector Mine 1999

SCEC
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Look! Its an Earthquake!

• InSAR
• Interferometric Synthetic Aperture Radar
• Differences 2 images to reveal changes in
  displacement

Peltzer, Crampe, Rosen 2000
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Defining the ECSZ

• GPS networks along a small circle about North
  American-Pacific pole of rotation
• Strain rates are very similar in orientation and
  magnitude
• Conclusion existence of a broad zone of shear

Savage et al., 1990
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ECSZ velocity field

• GPS arrays measure relative positions of stations
  over time
• position data are inverted for velocity field
• Relative to an arbitrary fixed point

McClusky et al., 2001
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About Block Models single fault

• Geologic Slip long term slip over geologic
  time
• Includes Interseismic Coseismic Deformation
• Calculate Interseismic deformation by subtracting
  Coseismic slip from Geologic slip

Meade et al., 2002
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Fault Slip from Block Model

• Block edges defined by faults, motion from GPS
• Blocks move in reference to a fixed point away
  from deformation zone
• Slip rate is calculated by projection of block
  velocity vector onto the fault plane
• Path integral constraint relative velocity
  between any two points is not dependent upon the
  path

Meade et al., 2002
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ECSZ Block Model with residuals

• Data and Model are consistent
• Blocks are bounded by major faults
• Slip rate calculated at locations along faults

McClusky et al., 2001
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Fault Slip Rate

• East west profiles should sum to 11 mm/yr
• Half of ECSZ shear north of Garlock is on Airport
  Lake/Owens Valley
• More than half of ECSZ shear south of Garlock is
  in Eastern Mojave
• Mojave Block has a clockwise rotation

McClusky et al., 2001