gretchen c. schmauder 1,2 , john n. louie 1,3 ,
Post on 23-Feb-2016
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Simulation of Seismic-Wave PropagationThrough the Lake Tahoe Basin,
Calif.-Nevada: A Scenario Approach toProbabilistic Shaking Hazard
Gretchen C. Schmauder1,2, John N. Louie1,3,Satish Pullammanappallil2, Kyle Gray1, Kevin McBean1,
Alexa McBean1, & Graham M. Kent1
1. Nevada Seismological Lab. & Dept. Geol. Sci. & Engin., Univ. of Nevada, Reno NV, USA2. Optim SDS, 200 S. Virginia St. Suite 560, Reno, NV USA; gretchens@optimsds.com
3. visiting Victoria University of Wellington to August 2014
Thanks to: J. M. Maloney (Univ. of Calif.
San Diego); Edgetech; Watershed Sciences; Tahoe Regional Planning Agency;
U.S. Forest Service
crack.seismo.unr.edu/NSZ
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1) FindingEarthquake Source Faults:Marine CHIRP under Lake TahoeDense LiDAR under trees
LV
LA
SF
Results:Only 3 faults!
(Pyramid L. has 100s)All normal, N-
strike, E-dip, E-W extension
M7.5 events in record
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CHIRP images sediments to 70 m below lake bottom with 25 cm resolution
Edgetech acousticCompressed HighIntensity RadarPulse (CHIRP)
With Univ. of California,San Diego
Slide/gravity deposits seen throughout Tahoe; dated & correlated by Shane Smith.
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Watershed Sciences airborne Light Detection and Ranging (LiDAR) imagery over 232,000 acres in the Tahoe basin
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2) Gravity and ReMi™ Assess Wave Trappingin Basins, and Geotechnical Amplification
AssembledBasinThickness
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AssembledVs30
200-mGrid Vs
AssembledVs30 Map
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Intense 3Dbasin effects
NSZ WTDPFRupture
from South
Large motions for: Steep slopes Small subbasins
3) Shake- Zoning
Scenario Predictions
Using Physics and
GeologyPGVShaking
Map
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How to explain hazard to the community?4) Probabilistic Mapping with ShakeZoning Scenarios
Frankel et al. USGS Seattle Basin – Annual Probability of Exceedance λ:
Sum up a limited number of scenarios: faults; rupture directivities. Examine Annual Rate of Exceedance (A.R.E.) of μ0=30 cm/s. Conflate PGV > 30 cm/s with higher A.R.E.; <30 cm/s, lower A.R.E.
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Shaking Map to Hazard Map
PGVShaking
Map
7x10-5/year
PGV rate
PGV rate A.R.E.Map
WTDPFSo. Rupture, One Scenario
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Now add up the A.R.E.s for the 6 fault scenarios:Result: a simple tool promoting resilience
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