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ReMi Applied Geophysics Spring Break 2010. Fariha Islam Gretchen Schmauder. Question. Can the ReMi method be used to locate faults in the Reno Basin?. Area Geology. NE trending faults Lacustrine, fluvial, and alluvial fan deposits Tertiary volcanic basement Active hot springs. - PowerPoint PPT Presentation
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ReMi Applied GeophysicsSpring Break 2010
Fariha IslamGretchen Schmauder
Question
• Can the ReMi method be used to locate faults in the Reno Basin?
Area Geology
• NE trending faults• Lacustrine, fluvial, and alluvial fan
deposits• Tertiary volcanic basement• Active hot springs
Abbott and Louie (2000)
Project Constraints
• Sedimentary cover can be greater than 1000 meters thick (Abbott and Louie, 2000).
• ReMi method typically used to depths less than 100 meters.
ReMi Method
• Surface wave velocity spectral analysis used to determine shallow earth structures
– Typically used to determine IBC site classification, rippability, void detection, and fault mapping.
ReMi Method
Fundamental Mode Rayleigh Wave
Transect 3 along lakeside dr.
ReMi Survey
Transect 4 along lakeside dr.
Survey location
Scott et al. (2004)
20 Transects along Manzanita Ln and adjacent streets
First order: shear velocity correlates to surficial geology
Tr ansect 14 Vs30 Model
-200
-150
-100
-50
00 500 1000 1500
Shear Wave Vel ocity (m/ s)
Depth
(m
)
Vs30 = 827 m/ s
NEHRP C l ass B
Tr ansect 2 Vs Model
-200
-150
-100
-50
00 100 200 300 400 500
Shear Wave Vel ocity (m/ s)
Depth
(m
)
Vs30 = 301 m/ s
NEHRP C l ass D
Tr ansect 5 Vs Model
-200
-150
-100
-50
00 500 1000
Shear Wave Vel ocity (m/ s)
Depth
(m
)
Vs30 = 407 m/ s
NEHRP C l ass C
Frary (2009)
Abbott and Louie (2000)
Second order: shear velocity correlates to depth to bedrock
Third order: correlation between shear velocity and faults?
Conclusions
• Transect velocity models reflect regional geology and depth to bedrock
• Correlation between velocity models and faults is inconclusive
• Indication that the alluvium has a lower shear velocity due to faulting
Further Work
• Additional ReMi lines south of Manzanita Lane to verify higher velocity in alluvium
• Better constraint on area faulting
references