School of Earth and EnvironmentSchool of Earth and EnvironmentFACULTY OF ENVIRONMENTFACULTY OF ENVIRONMENT

Scattering of PKKP and PScattering of PKKP and P''PP'' --

A tool for mapping fineA tool for mapping fine--scale scale

mantle heterogeneitymantle heterogeneity

Sebastian RostSebastian Rost University of LeedsUniversity of Leeds

Paul Earle Paul Earle USGSUSGS

Leon Leon FoksFoks University of Leeds/Colorado School of MinesUniversity of Leeds/Colorado School of Mines

Peter ShearerPeter Shearer Scripps Institution of OceanographyScripps Institution of Oceanography

Stacking stacks experimentStacking stacks experiment::

> 1200 earthquakes > 1200 earthquakes EQEQ’’ss, aligned by origin time, aligned by origin time

Slowness info retained in a global stackSlowness info retained in a global stack

Important potential for scattering analysesImportant potential for scattering analysesRost,,Thorne, Garnero [SRL, 2005]

[[HedlinHedlin and Shearer, 2000]and Shearer, 2000]

Why scattering?Why scattering?

•• Sensitive to smallSensitive to small--scale heterogeneities of velocity and densityscale heterogeneities of velocity and density

•• CMB topography (roughness)CMB topography (roughness)

•• PKP; PKP; PcPPcP; ; PPdiffdiff; PKKP; PKKP

4 scattering layers: 4 scattering layers: 0 0 –– 200 200 2%2% 4 km4 km200 200 –– 600600 2%2% 4 km4 km

600 600 –– 17001700 0.5%0.5% 8 km8 km

1700 1700 –– 2890 2890 0.5%0.5% 8 km8 km

VelocityVelocity CorrelationCorrelation

Depth [km] Depth [km] contrastcontrast Length [km]Length [km]

[Shearer and Earle, 2004][Shearer and Earle, 2004]

PKKPPKKP

PKKP ScatteringPKKP Scattering

PKPKbcbc to to PKPKbcbc

PKK to PPKK to P

PKP to PPKP to P

P to PKPP to PKP

PKKP ScatteringPKKP Scattering

[after Earle, 2002][after Earle, 2002]

[Earle, 2002][Earle, 2002]

PKKP scattering characteristicsPKKP scattering characteristics

0101--MAYMAY--1990_16:12 1990_16:12 ⇒⇒ YKAYKA

Lat: Lat: 58.8258.82°°

Lon: Lon: --156.86156.86°°

H:H: 211 km211 km

MMbb:: 6.36.3

∆∆:: 20.5820.58°°

ΘΘ:: 278.82278.82°°

Energy MaximumEnergy Maximum

uumaxmax= 3.7 s/= 3.7 s/°°

ΘΘmaxmax = 146= 146°°

1717--JUNJUN--1996_11:221996_11:22

Lat: Lat: --7.147.14°°

Lon: Lon: 122.59122.59°°

H:H: 587 km587 km

MMbb:: 7.97.9

∆∆:: 49.3549.35°°

ΘΘ:: 111.95111.95°°

Energy MaximaEnergy Maxima

uumaxmax= 2.7 s/= 2.7 s/°° and 2.4 s/and 2.4 s/°°

ΘΘmaxmax = 218= 218°° and 28and 28°°

PKKP scattering example PKKP scattering example -- GBAGBA

PP''PP'' (PKPPKP)(PKPPKP)

PP''PP'' scatteringscattering

PKPPKPbcbc to to PKPPKPbcbc scatteringscattering

PP''PP'' (PKPPKP) Scattering(PKPPKP) Scattering

PP''PP'' scatteringscattering

Vertical profilingVertical profiling

ConclusionsConclusions

� Scattered Scattered wavefieldwavefield contains important information contains important information

about the smallabout the small--scale heterogeneity of the Earthscale heterogeneity of the Earth

�� PKKP scattering resolves CMB (DPKKP scattering resolves CMB (D") scattering") scattering

�� PP'P' scattering can be used to sample heterogeneities in 'P' scattering can be used to sample heterogeneities in

the upper, mid and lower mantlethe upper, mid and lower mantle

�� Combined PKKP and PCombined PKKP and P'P' can allow vertical profiles of 'P' can allow vertical profiles of

mantle heterogeneities from CMB to surfacemantle heterogeneities from CMB to surface

�� Preliminary results indicate regional variation of Preliminary results indicate regional variation of

scattering potentialscattering potential