sierra nevada earthscope project results - geological society of washington meeting 11/13/13

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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