sierra nevada earthscope project results - geological society of washington meeting 11/13/13
TRANSCRIPT
The Unusual The Unusual Lithosphere Beneath Lithosphere Beneath
the Sierra Nevadathe Sierra NevadaResults from Results from
the First Major the First Major EarthScope EarthScope
Seismic Seismic DeploymentDeployment
“Simple” Mountains
“Complicated” Mountains
The (Western) Sierra Nevada
~100 meters
The (Eastern) Sierra Nevada
~3 km
A Complex Geologic Story
Modern data,new ideas
Few recent geophysical constraints
Time Dependent Mantle
After Ducea, 1998 & 2002
Zandt et al., 2004
Lithospheric Foundering
Seismic Fieldwork
Example Event
P
Receiver Functions
Iterdecon Method
Ligorría & Ammon, 1999
1: u(t)z u(t)r g(t)r
Progressively finds time lag for largest difference between two signals.
2: u(t)r – (g(t)r ∗ u(t)z) u(t)r
Repeat 1 until the misfit of 2 is very small.
MATHMATH
Example Receiver Functions
P
CCP Stacking
Southern Sierra
N
Central Sierra
N
Central Sierra
N
Northern Sierra
N
Western SierraN
Eastern Sierra FlankN
IncreasesE to W
Deepest under westernSierra
Moho Depth
SNEP Tomography
SNEP Tomography
Jones et al., In Review
A Live View
A Live View
Overall Interpretation
George Zandt, Hersh Gilbert, Tom Owens, Craig Jones, Susan Beck, Jon Patchett, Mihai Ducea, Clem Chase, Rick Bennett, Josh Calkins, Ian Bastow, Ken Dueker, Matt Fouch, Philip Crotwell, Megan Anderson, Lara Wagner, Arda Ozacar, Berk Biryol, Christine Gans, Lepolt Linkimer, Ryan Porter, Koichi Sakaguchi, Aaron Wech, Steve Hansen, Josh Stachnik, John Jasbinsek, Chris Harig, Owen Hurd, Nickles Badger, Will Huff, Serkan Arca, Soledad Velasco
“The Frassettos”: Ron, Gale, Kendra
My friends in Tucson and elsewhere: Anna, Keeler, Tibs, Toby especially
Our National Science Foundation, in awards of different forms and amounts to me and others
And …Megan (of Fogarty.m)
EarthScope-USArray
EarthScope-USArray
Iterdecon Method
Ligorría & Ammon, 1999
1: u(t)z u(t)r g(t)r
Progressively finds time lag for largest difference between two signals.
2: u(t)r – (g(t)r ∗ u(t)z) u(t)r
Repeat 1 until the misfit of 2 is very small.
Southern Sierra
N
Central Sierra
N
Northern Sierra
N
FoothillsN
Eastern SierraN
Basin and RangeN
Regional and local trends
Multiple proxies
Crustal Vp/Vs
DecreasesE to W
Correlates with crustal thickness
Moho Amplitu
de
Interface Resolution
Moho Sensitivity
Forward Modeling
SNEP Local Earthquakes
>30
20-30
depth (km)10-20
<10
Recent Sierra Uplift - GPS
Hammond et al., 2012
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