TEAC2007 FAULTING IN EASTERN SIERRASDan Jalbert Theresa Cawthorn

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TEAC-2007 FAULTING IN EASTERN
SIERRAS Dan Jalbert Theresa
Cawthorn

• What are faults?
• Fractures in crust where noticeable movement
  has occurred

CAUSE OF FAULTS? Stress forces at work on the
earth Three kinds Tensional Compressional Shea
ring
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NORMAL FAULTING
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STRIKE-SLIP FAULTING
Shearing (scissor-type) stress causes one block
to slide past the other Two types right and
left lateral
Aerial view of right-lateral fault. Near Las
Vegas, Nevada.
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Tahoe Basin

• Tahoe is a graben formed by an extensional fault
  between tha Sierra Nevada range and the Carson
  Range.
• Faults in the area include the Tahoe Sierra
  frontal fault zone, West Tahoe fault, North Tahoe
  fault Incline Village all normal faults
• Possible left lateral strike slip on faults in
  moraines in Meeks Bay (controversial)

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Walker Lane

• Discontinuous sets of right-lateral strike-slip
  faults a combination of crustal rotation with
  localized left-lateral strike-slip faults
  (Wesnousky, 2005)
• Normal faulting from the Wassuk Range westward to
  Lake Tahoe since 15 Mya.
• Fairview Peak December 1954. Normal displacement
  5 meters of normal slip with about 4 meters of
  right-lateral slip.
• Dixie Valley December 1954. Nearly all normal
  slip about 2-3 meters of offset.
• Candelaria Hills region transition to NE
  striking left-lateral strike-slip faults. (NE
  striking faults are left-lateral strike-slip and
  NW striking faults are right-lateral strike-slip)
  

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From Wesnousky, 2005
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Southern Walker Lane Belt

• Fish Lake Valley, Owens Valley, Furnace Creek,
  White Mountains faults right-lateral strike
  slip faults.
• Higher slip rates than northern Walker Lane
  faults.
• Deep Springs Valley half-graben between the Fish
  Lake Valley and Owens Valley fault

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Long Valley Caldera

• 760,000 yrs ago The Long Valley Caldera
  continuously exploded for a week.
• Creating a ring fracture (normal) fault system.
  This fault is intersected by Hilton Creek fault
  coming down from McGee Canyon.
• Swarm activity in the south moat is on an e-w
  right lateral strike-slip fault zone

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Long Valley Caldera, continued

• The Inyo-Mono chain may be on a n-s striking
  fault system
• Seismicity south of the caldera is on
  left-lateral strike-slip faults
• Only 1 of the 4 May 1980 magnitude 6 earthquakes
  was on a mapped fault

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