Stanford Geothermal Workshop

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Methodology for Obtaining Constraints on Ground
Motion from Precariously Balanced Rocks 
Rasool Anooshehpoor, James N. Brune and Yuehua
Zeng
Nevada Seismological Laboratory University of
Nevada, Reno
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Groups of precariously balanced rocks near active
faults 

• are effectively low-resolution seismoscopes
• have the potential to provide constraints on
  ground motions

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Qualifications 

• Evolve naturally
• Have time scales for evolution and stability much
  longer than the recurrence time for large
  earthquakes in the region

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Honey Lake, Northern California
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Yucca Mountain, Southern Nevada
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Methodology 

• Date the age of the rock surface
• Determine the quasi-static toppling acceleration
  and rock dimensions in the field
• Estimate dynamic toppling accelerations from 2-D
  rocking-motion simulations

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Important Parameters a and R
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Free Rocking Motion
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Shake Table Tests of Real Rocks
Input Motions 

• Horizontal components of the 17 August 1999
  Turkey earthquake recorded in Izmit, Turkey.
• Horizontal components of two M8 synthetic
  accelerograms at 15 km from the San Andreas
  fault.
• Chancellor nuclear explosion record scaled to an
  equivalent 1000 kt at 10 km

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Input Motions
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LJB-N x 0.6
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LJB-N x 1.3
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LJB-E x
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Izmit-N x 1.4
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Izmit-N x 1.7
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Izmit-E x 1.9
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Calibration of Methodology Using  

• A previously identified precarious rock possibly
  toppled by the 16 October 1999 Hector Mine
  earthquake
• Toppled tombstones during the 26 September 2003
  Tokachi-Oki earthquake, Japan

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Kushiro Cemetery About 5000 tombs 10
damaged Closest Strong Motion Station 1 km
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Kushiro Cemetery About 5000 tombs,
10 Damaged. Closest strong motion is 1 km away.
PGA0.42g
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Located at the weather station, North of Reno.
This station is used as a telemetry node, as well.
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.and in case you were wondering..
New Zealand precarious rocks 
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Shake Table Tests
Comparisons of Numerical and Shake-Table Results 
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Input Motions
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Izmit-N x 1.6
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Izmit-N x 1.0
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Izmit-N x 1.1
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LJB-E x ?
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LJB-E x 0.6
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Makubetsu Nukanai Cemetery A total of 49
tombs 31 toppled 8 rotated/translated Closest
Strong Motion Station 16 km
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Makubetsu Cemetery A total of 520 tombs 59
toppled 31 rotated/translated Closest Strong
Motion Station 6 km