Lithospheric Structure of the Gulf of California – Salton Trough Region,

NARS-Baja Array

Working Group:Robert Clayton, CaltechDon Forsyth, BrownAntonio Gonzalez-Fernandez, CICESECraig Jones, ColoradoCecillio Rebollar, CICESEJose Romo-Jones, CICESE

Science Questions:•What is the rifting process and how does it vary from north to south in the Gulf•What is the role of the remnant slab – where does it exist.

Methods•Map of the Moho from seismic and other geophysical methods.•Map of the lithosphere/asthenosphere boundary.•Velocity Variations from tomography studies.•Flow directions from anisotropy•Current strain from earthquakes

Products•3D regional-scale velocity model•Earthquake catalogue.

Lewis et al, 2001

Ichinose et al, 1996

Receiver Functions

Receiver Functions – Southern California Seismic Network

Yan and Clayton, 2006

Crustal Thickness From Surface Waves

Yang and Forsyth, 2005

NARS-Baja / RESBAN Array

April, 2002 – April, 2007

http://www.data.scec.org/NARS-Baja/

Receiver Functions – Gulf of California

Persaud, Perez-Campos and Clayton, 2005

NARS-Baja Station NE71 – Northern Baja Pennisula

NARS-Baja Stations NE78 & NE79 – Southern Baja Peninsula

NARS-Baja Station NE75 – Central Baja Peninsula

Cross-Peninsula Profile

Lopez-Pineda et al, 2005

I II IIIAlong Peninsula Profiles

Romo, Gomez-Trevino, Esparza, Garcia-Abdesiem, and Flores-Luna, 2003

Electrical Profile

Regional 3D Velocity From Surface Waves and Receiver Functions

DiLuccio, Clayton, Persaud, Perez-Campos, 2005

Rayliegh Wave Group Velocity Dispersion Curves for Four Events

DiLuccio, Clayton and Persaud, AGU, UGM, 2005

3D Regional-scale velocity model for the Gulf of California

DiLuccio, Clayton and Persaud, AGU, UGM, 2005

Gonzalez-Fernandez et al, 2005

The 2002 Gulf of California Seismic Experiment Lizarralde et al

Column

Moho

Top

col 23.456 -117.234 123.0 SAMPLE1 lay 0.0 DEN 2700 VS 3.5 DVS 0.015 VP 5.0 DVP 0.015 TOP lay 5.0 DEN 2700 DDEN 10.0 VS 3.6 VP 6.0 DVP -0.02 lay 8.0 DEN 2800 VS 4.5 VP 7.0 MOHO

Interface Names

Column Description

Column Description

DEN, DDEN - densityVS, DVS - shear velocityVP, DVP - P-wave velocityQS, DQS - S attenuationQP, DQP - P attenuation???? - anisotropy

Parameters

Moho

Top

(lat,lon,z)

SCSN Station JCS – Rapid Variations in Moho

Rayleigh waves

Love waves

7071-R7071-L8081-R8081-L

Initial model

Flow Direction From S-Wave Anisotropy – Rayleigh Vs Love Waves

Noise CorrelationMicroseism – 6 sec – station NE81

Infrasonic – 30-100 sec – NE82

Receiver Functions of Deeper Interfaces

Perez-Campos, Persaud and Clayton, UGM, AGU 2004

Song and Helmberger, 2002