This presentation provides a brief introduction to the seismic data, teleseismic migration imaging method, and preliminary imaging results/interpretation that would later form the basis of Chapter 2 of my Ph.D. thesis. It was given in 2010 at the SSA meeting in Portland, OR, and won a Student Presentation Award. The final versions of the images and details of their interpretation are available in Pearce et al., JGR 2012 and Chapter 2 of my Ph.D. thesis (see LinkedIn profile for references).

1. Imaging with sca-ered teleseismic waves:
data, method and applica7on to
the Hellenic subduc7on zone
F.D. Pearce1 and S. Rondenay1
1 Dept. of Earth, Atmospheric,
and Planetary Sciences, MIT
Frederick D. Pearce Modified aKer Project MEDUSA proposal

2. Subducted
Crust
Surface
Seismics
Seismic images of lithosphere and upper-mantle structure
provide key constraints on large-scale tectonic processes
Travel7me
Tomography
Mo7va7on
Moho
Teleseismic
Migra7on
40 km
Frederick D. Pearce

3. Bostock et al., JGR 2001
Teleseismic migra7on of sca-ered waves
Objec7ve
Frederick D. Pearce

4. Data
Northern Line (NL)
* 71 events
Southern Line (SL)
* 51 events
SS
NS
CTF
Frederick D. Pearce

5. Method
Rondenay, Survey Geophysics 2009
I) Isolate sca-ered teleseismic body waves
0
50
0
50
0
50
0
50
0
50
Time [sec]
1) Align wavefields
2) Isolate incident P
3) Isolate sca-ered
P, SV, and SH
Frederick D. Pearce

6. Method
II) Apply teleseismic migra7on algorithm
P
* Propaga7on within a 1D background model
* 2D Generalized Radon transform inversion Frederick D. Pearce
Rondenay, Survey Geophysics 2009

7. XSL [km]
Depth [km]
SL Imaging*
Δβ = +/- 5% Δα = +/- 10%
XSL [km]
Frederick D. Pearce * Early version of images, see final in Pearce et al., JGR 2012

8. XSL [km]
Depth [km]
SL Imaging*
P S
XSL [km]
P P S
P S Sv P S Sh
Frederick D. Pearce * Early version of images, see final in Pearce et al., JGR 2012

9. SL Lateral Varia7ons*
Depth [km]
1T
3T
2T
2T
XSL [km]
Frederick D. Pearce * Early version of images, see final in Pearce et al., JGR 2012

10. XSL [km]
Depth [km]
SL Imaging*
Subducted
Crust
Con3nental
Moho
Eclogi3za3on
Oceanic
Moho
Δβ from -5% (red) to 5% (blue)
Frederick D. Pearce * Early version of image, see final in Pearce et al., JGR 2012

11. NL Imaging*
XNL [km]
Depth [km]
Δβ from -5% (red) to 5% (blue)
Subducted
Crust
Con3nental
Moho
Frederick D. Pearce * Early version of image, see final in Pearce et al., JGR 2012

12. Results: NL vs. SL*
Moho Contour Map
CROP Project
Finee, 2005
XST
Frederick D. Pearce * Early version of schema7c, see final in Pearce et al., JGR 2012

13. Conclusions
Teleseismic migra7on provides high-resolu7on images
of lithosphere and upper-mantle structure
Images from the western Hellenic subduc7on zone show
* oceanic crust beneath southern segment
* con3nental crust beneath northern segment
* differen7al rollback between SS and NS
Frederick D. Pearce