introduction to the receiver function method · 2018. 2. 6. · 1introduction. 2crustal vp/vs ratio...

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Introduction to the receiver function method Frederik Tilmann (+ material from Rainer Kind) 4D-MB SPP Short Course, 1 February 2018 Tilmann (GFZ,FUB) Receiver Functions 1/0

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Page 1: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Introduction to the receiver function method

Frederik Tilmann (+ material from Rainer Kind)

4D-MB SPP Short Course, 1 February 2018

Tilmann (GFZ,FUB) Receiver Functions 1 / 0

Page 2: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Outline

1 Introduction

2 Crustal Vp/Vs ratio and Moho depth from stacking of multiples

3 Common Conversion Point Stacks (CCCP)

paired with lecture on seismic anisotropy (Georg Rumpker)

Tilmann (GFZ,FUB) Receiver Functions 2 / 0

Page 3: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Outline

1 Introduction

2 Crustal Vp/Vs ratio and Moho depth from stacking of multiples

3 Common Conversion Point Stacks (CCCP)

Tilmann (GFZ,FUB) Receiver Functions 3 / 0

Page 4: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Target: Imaging subsurface structure, discontinuities

TRANSALP profile Vibroseis+Explosion+passive 1998,2001 [TRANSALP Working Group, 2002]

Controlled source reflectionseismology:

Use reflections of P energy

Method of choice for shallowstructure but energy does mostlynot penetrate deeply

No information on S velocity

Very expensive to carry out

⇒ Use earthquakes as energy source

⇒ The energy is coming from below

⇒ We need to use conversionsinstead of reflections

Tilmann (GFZ,FUB) Receiver Functions 4 / 0

Page 5: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Target: Imaging subsurface structure, discontinuities

TRANSALP profile Vibroseis+Explosion+passive 1998,2001 [TRANSALP Working Group, 2002]

Controlled source reflectionseismology:

Use reflections of P energy

Method of choice for shallowstructure but energy does mostlynot penetrate deeply

No information on S velocity

Very expensive to carry out

⇒ Use earthquakes as energy source

⇒ The energy is coming from below

⇒ We need to use conversionsinstead of reflections

Tilmann (GFZ,FUB) Receiver Functions 4 / 0

Page 6: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Moho depth and Vp/Vs ratios

Lombardi et al. [2008]

VP/VS varies typically 1.6–2.0, stronglyindicative of lithology,felsic ⇒ mafic implies small ⇒ large VP/VS

values.

Tilmann (GFZ,FUB) Receiver Functions 5 / 0

Page 7: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Basics: P and S waves

VP =

√K + 4

ρ

K Bulk modulus

µ Shear modulus

ρ Density

VS =

õ

ρ

At the same period S wavelength is shorter due to shorter propagation velocity

Tilmann (GFZ,FUB) Receiver Functions 6 / 0

Page 8: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Basics: P and S waves

VP =

√K + 4

ρ

K Bulk modulus

µ Shear modulus

ρ Density

VS =

õ

ρ

At the same period S wavelength is shorter due to shorter propagation velocity

Tilmann (GFZ,FUB) Receiver Functions 6 / 0

Page 9: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P and S wave: interaction with interface

Incident P

Incident P ⇒ converted SV wave(except when exactly verticallyincident)

No SH wave (T component)converted by flat interface

Also works the other way round:incident SV ⇒ converted P

Note that in reality the different types of motion overlap and affect the same volume.

Tilmann (GFZ,FUB) Receiver Functions 7 / 0

Page 10: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P and S wave: interaction with interface

Incident P

R

Z

Incident P ⇒ converted SV wave(except when exactly verticallyincident)

No SH wave (T component)converted by flat interface

Also works the other way round:incident SV ⇒ converted P

Note that in reality the different types of motion overlap and affect the same volume.

Tilmann (GFZ,FUB) Receiver Functions 7 / 0

Page 11: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P and S wave: interaction with interface

Incident P

R

Z

Refracted P

Converted S

V

Incident P ⇒ converted SV wave(except when exactly verticallyincident)

No SH wave (T component)converted by flat interface

Also works the other way round:incident SV ⇒ converted P

Note that in reality the different types of motion overlap and affect the same volume.

Tilmann (GFZ,FUB) Receiver Functions 7 / 0

Page 12: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P and S wave: interaction with interface

Incident P

R

Z

Refracted P

Converted S

V

Ref

lect

ed P

Ref

lect

/con

v S

V

Incident P ⇒ converted SV wave(except when exactly verticallyincident)

No SH wave (T component)converted by flat interface

Also works the other way round:incident SV ⇒ converted P

Note that in reality the different types of motion overlap and affect the same volume.

Tilmann (GFZ,FUB) Receiver Functions 7 / 0

Page 13: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P and S wave: interaction with interface

Incident P

R

Z

Refracted P

Converted S

V

Ref

lect

ed P

Ref

lect

/con

v S

V

Incident P ⇒ converted SV wave(except when exactly verticallyincident)

No SH wave (T component)converted by flat interface

Also works the other way round:incident SV ⇒ converted P

Note that in reality the different types of motion overlap and affect the same volume.

Tilmann (GFZ,FUB) Receiver Functions 7 / 0

Page 14: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P and S wave: interaction with interfaceTechnical details

Wavefronts along interface need to stay in phase: ⇒ Snell’s law: sin ι1P

VP= sin ι2S

VS

⇒ Converted S waves propagate more steeply than their originating P waves

Tilmann (GFZ,FUB) Receiver Functions 8 / 0

Page 15: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Using RF for imaging discontinuity depths

P wave from earthquake

Direct P

P-converted-SV at D

Seismic discontinuities

M

D

P-converted-SV at M

Use time-separation of waves converted fromP-to-S at discontinuities underneath thereceiver.

Take home

Interface with velocity increase with depthshows up as positive wiggle, velocity decrease asnegative wiggle.

Fast-to-slow (e.g. Moho)

Slow-to-fast (e.g. magma chamber, LAB)

Page 16: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Using RF for imaging discontinuity depths

P wave from earthquake

Direct P

P-converted-SV at D

Seismic discontinuities

M

D

P-converted-SV at M

Use time-separation of waves converted fromP-to-S at discontinuities underneath thereceiver.

Take home

Interface with velocity increase with depthshows up as positive wiggle, velocity decrease asnegative wiggle.

Fast-to-slow (e.g. Moho)

Slow-to-fast (e.g. magma chamber, LAB)

Page 17: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Diffractions

Ryberg&Weber (2000) Rondenay [2009]

Anything that is not a smooth horizontal interface will give rise to diffractions, in particular also

topography of any interface.

Tilmann (GFZ,FUB) Receiver Functions 10 / 0

Page 18: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Incident P wave in a simple crust

R component(SV+P)

T component(SH)

Z component(P+SV)

P (norm.)

SV (norm.)

Page 19: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Incident P wave in a simple crust

R component(SV+P)

T component(SH)

Z component(P+SV)

P (norm.)

SV (norm.)

What are multiples?

Fig: A. Frassetto

NB: such a clean signal is rarelyachieved

Page 20: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P- and S-receiver functions

Methods – P and S Receiver Functions

P S Surface Waves

Tilmann (GFZ,FUB) Receiver Functions 12 / 0

Page 21: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

The making of a receiver functionMultiple effects build the seismograms

R component traces at station in Australia

[Kennett, 2002]

But: the conversions are hard to see in raw data becausein addition to the sequence of interfaces, the seismogramsare influenced by

Instrument response

Source complexity

Near-source structure (e.g. surface reflections)

Each effect is combined with the others by a processcalled convolution.Here, We are interested in receiver structure⇒ we do not need to know these effects in detail.

Tilmann (GFZ,FUB) Receiver Functions 13 / 0

Page 22: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Refresher: convolution and deconvolutionNoise-free synthetic data (T0 = 10s)

0 20 40 60 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Time (s)

Acc

eler

atio

n (m

/s)

∗Conv.

0 20 40 60 800

0.2

0.4

0.6

0.8

1

Time (s)

V

0 20 40 60 80

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Time (s)

V

NB Deconvolution is inherently unstable and needs to be regularised (different methods

available)! Aster et al. [2005]

Page 23: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Refresher: convolution and deconvolutionNoise-free synthetic data (T0 = 10s)

0 20 40 60 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Time (s)

Acc

eler

atio

n (m

/s)

∗Conv.

0 20 40 60 800

0.2

0.4

0.6

0.8

1

Time (s)

V

0 20 40 60 80

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Time (s)

V

−−−→Decon

NB Deconvolution is inherently unstable and needs to be regularised (different methods

available)! Aster et al. [2005]

Page 24: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Refresher: convolution and deconvolutionNoise-free synthetic data (T0 = 10s)

0 20 40 60 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Time (s)

Acc

eler

atio

n (m

/s)

∗Conv.

0 20 40 60 800

0.2

0.4

0.6

0.8

1

Time (s)

V

0 20 40 60 80

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Time (s)

V

−−−→Decon

−20 0 20 40 60 80 100−0.2

0

0.2

0.4

0.6

0.8

1

1.2

Time (s)

Acc

eler

atio

n (m

/s)

NB Deconvolution is inherently unstable and needs to be regularised (different methods

available)! Aster et al. [2005]

Page 25: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Refresher: convolution and deconvolutionNoisy synthetic data (T0 = 10s)

0 20 40 60 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Time (s)

Acc

eler

atio

n (m

/s)

∗Conv.

0 20 40 60 800

0.2

0.4

0.6

0.8

1

Time (s)

V

0 20 40 60 800

1

2

3

4

5

Time (s)

V

−−−→Decon

NB Deconvolution is inherently unstable and needs to be regularised (different methods

available)! Aster et al. [2005]

Page 26: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Refresher: convolution and deconvolutionNoisy synthetic data (T0 = 10s)

0 20 40 60 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Time (s)

Acc

eler

atio

n (m

/s)

∗Conv.

0 20 40 60 800

0.2

0.4

0.6

0.8

1

Time (s)

V

0 20 40 60 800

1

2

3

4

5

Time (s)

V

−−−→Decon

0 20 40 60 80

−4

−3

−2

−1

0

1

2

3

4

5

Time (s)

Acc

eler

atio

n (m

/s)

NB Deconvolution is inherently unstable and needs to be regularised (different methods

available)! Aster et al. [2005]

Page 27: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Refresher: convolution and deconvolutionNoisy synthetic data (T0 = 10s)

0 20 40 60 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Time (s)

Acc

eler

atio

n (m

/s)

∗Conv.

0 20 40 60 800

0.2

0.4

0.6

0.8

1

Time (s)

V

0 20 40 60 800

1

2

3

4

5

Time (s)

V

−−−→Decon

0 20 40 60 80

−4

−3

−2

−1

0

1

2

3

4

5

Time (s)

Acc

eler

atio

n (m

/s)

NB Deconvolution is inherently unstable and needs to be regularised (different methods

available)! Aster et al. [2005]

Page 28: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

The making of a receiver functionIsolating the receiver effect by deconvolution

The ‘receiver function’ idea: Use the P wave as proxy for the incident wavesignature (source∗ near source∗mantle propagation∗instrument) [Vinnik, 1977,

Langston, 1979].

Deconvolve vertical component from radial component to obtain RF

Deconvolution

Deconvolution - division in freq domain (fourier transformed time series)

Rf (ω) = c(ω)R(ω)

Z(ω)

The deconvolution removes source and instrument effects (cancel in division)

⇒ RF is only dependent on the structure below receiver and incidence angle

Page 29: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

The making of a receiver functionIsolating the receiver effect by deconvolution

The ‘receiver function’ idea: Use the P wave as proxy for the incident wavesignature (source∗ near source∗mantle propagation∗instrument) [Vinnik, 1977,

Langston, 1979].

Deconvolve vertical component from radial component to obtain RF

Deconvolution

Deconvolution - division in freq domain (fourier transformed time series)

Rf (ω) = c(ω)R(ω)

Z(ω)

The deconvolution removes source and instrument effects (cancel in division)

⇒ RF is only dependent on the structure below receiver and incidence angle

Page 30: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

The making of a receiver functionIsolating the receiver effect by deconvolution

The ‘receiver function’ idea: Use the P wave as proxy for the incident wavesignature (source∗ near source∗mantle propagation∗instrument) [Vinnik, 1977,

Langston, 1979].

Deconvolve vertical component from radial component to obtain RF

Deconvolution

Deconvolution - division in freq domain (fourier transformed time series)

Rf (ω) = c(ω)R(ω)

Z(ω)

The deconvolution removes source and instrument effects (cancel in division)

⇒ RF is only dependent on the structure below receiver and incidence angle

Page 31: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

The making of a receiver functionVariants: component decomposition

— —[Rondenay, 2009]

Deconvolve Z from R, or L from Q.

Take-home

ZRT RF will have large peak at 0 s/0 km. Sedimentary basins can lead to a slight shift of

LQT RF will have nearly zero amplitude at 0 s/0 km. In presence of thick sediments, strongamplitudes near 0 km / 0 s.

For deeper structures no strong difference between both methods.

Tilmann (GFZ,FUB) Receiver Functions 16 / 0

Page 32: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

The making of a receiver functionVariants: component decomposition

— —[Rondenay, 2009]

Deconvolve Z from R, or L from Q.

Take-home

ZRT RF will have large peak at 0 s/0 km. Sedimentary basins can lead to a slight shift of

LQT RF will have nearly zero amplitude at 0 s/0 km. In presence of thick sediments, strongamplitudes near 0 km / 0 s.

For deeper structures no strong difference between both methods.

Tilmann (GFZ,FUB) Receiver Functions 16 / 0

Page 33: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P- and S receiver functions

Crustal multiples in P-RF obscure mantle discontinuities

As conversion appear before main phase, this does not affect S-RF (buthigher noise level, lower frequency, potential contamination by other phases)

Page 34: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Outline

1 Introduction

2 Crustal Vp/Vs ratio and Moho depth from stacking of multiples

3 Common Conversion Point Stacks (CCCP)

Tilmann (GFZ,FUB) Receiver Functions 18 / 0

Page 35: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Moveout of direct phases and multiples

[Kind and Yuan, 2011]

Fig: A. Frassetto

Tilmann (GFZ,FUB) Receiver Functions 19 / 0

Page 36: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

H − κ stacking methodIntroduced by Zhu [2000] – κ = VP/VS

Observables:

∆tPs = H(ηS − ηP ) (1)

∆tPpPms = h(ηS + ηP ) (2)

∆tPsPms = 2hηS (3)

(Definitions:

ηP =√

V −2P − p2, ηS =

√V −2

S − p2)

p is given by distance of earthquakeUnknowns:

H Depth to Moho

VP Average P velocity crust

VS Average S velocity crust

Redundant equations ⇒ only 2 param.can bedetermined independently.Usually one fixes VP and searches forcombinations of H and κ = VP/VS that fit theobserved RFs.Based on trial values, calculate ∆tPS,PpmS,PsPms

and calculate

A(H, κ) = 0.7Rf (∆tPs )+0.2Rf (∆tPpPs )−0.1Rf (∆tPpSs )Tilmann (GFZ,FUB) Receiver Functions 20 / 0

Page 37: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Good data: permanent stations in CaliforniaZhu and Kanamori [2000]

Tilmann (GFZ,FUB) Receiver Functions 21 / 0

Page 38: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile (Southern Madagascar)Rindraharisaona et al. [2017]

44˚ 46˚ 48˚

-24˚

-22˚

-20˚

A

B

C

MS

01

MS

02

MS

03

MS

04

MS

05

MS

06

MS

07

MS

08

MS09

MS

10

MS11

MS

12

MS

13

MS

14

MS

15

MS

16 M

S17 M

S18 M

S19

MS

20

MS

21

MS

22

MS

23

MS24

VO

I

LO

NA

AM

01

AM04

AM

05

AM06

AM07

AM08

AM

09 AM10

AM12

AM13

AM

14

AM

15

AM16

AM

17

AM18

AM19

AM

20

AM21

AM22

AM23

RUM1

RUM2

RUM3

RUM4

RUM5

FOMA

MAHA

Archean

Proterozoic

Morondava basin

Br

Bg-Rn

Bg-Rn

Zz

If

If

Am

Ej

Cn

Cr Cb-Jr

Vb

Ad

An

Ik

ItAt

Ag

Vl

SELASOMA

SELASOMA

RHUM-RUM

MACOMO

Permanent

44˚ 46˚ 48˚ 50˚-26˚

-24˚

-22˚

-20˚

-18˚

-16˚

-14˚

-12˚

30

60

90

120

150

180

Typical temporary array data (1-2 years deployment)

Tilmann (GFZ,FUB) Receiver Functions 22 / 0

Page 39: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile (Southern Madagascar)ZR Receiver function stacks

0 5 10 15 20 25

time(s)

MS01 (05)

MS02 (09)

MS03 (12)

MS04 (12)

LONA (12)

MS05 (10)

Cenozoic-Cretaceous

0 5 10 15 20 25

time(s)

MS06 (10)

Carboniferous-Jurassic

MS07 (12)

MS08 (12)

AM21 (08)

MS09 (13)

0 5 10 15 20 25

time(s)

MS24 (21)

Cretaceous volcanic

AM02 (02)

AM01 (07)

RUM2 (9)

RUM1 (14)

MAHA (14)

RUM3 (10)

0 5 10 15 20 25

time(s)

MS10 (20)

Androyen domain

MS11 (11)

AM20 (02)

AM22 (13)

MS12 (16)

0 5 10 15 20 25

time(s)

MS13 (16)

Anosyen domain

AM19 (09)

AM23 (09)

AM17 (12)

MS14 (05)

FOMA (36)

RUM4 (22)

RUM5 (21)

0 5 10 15 20 25

time(s)

MS15 (24)

Ikalamavony domain

MS16 (16)

AM16 (10)

AM18 (08)

0 5 10 15 20 25

time(s)

VOI (51)

Antananarivo domain

AM14 (10)

AM13 (08)

MS17 (16)

AM15 (07)

MS18 (08)

AM08 (06)

MS19 (20)

AM06 (11)

AM07 (14)

MS20 (16)

MS21 (11)

AM09 (10)

AM11 (02)

MS22 (16)

AM04 (07)

MS23 (24)

AM12 (10)

AM10 (06)

Tilmann (GFZ,FUB) Receiver Functions 23 / 0

Page 40: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile (Southern Madagascar)ZR Receiver function stacks

Archaean:

0 5 10 15 20 25

time(s)

MS01 (05)

MS02 (09)

MS03 (12)

MS04 (12)

LONA (12)

MS05 (10)

Cenozoic-Cretaceous

0 5 10 15 20 25

time(s)

MS06 (10)

Carboniferous-Jurassic

MS07 (12)

MS08 (12)

AM21 (08)

MS09 (13)

0 5 10 15 20 25

time(s)

MS24 (21)

Cretaceous volcanic

AM02 (02)

AM01 (07)

RUM2 (9)

RUM1 (14)

MAHA (14)

RUM3 (10)

0 5 10 15 20 25

time(s)

MS10 (20)

Androyen domain

MS11 (11)

AM20 (02)

AM22 (13)

MS12 (16)

0 5 10 15 20 25

time(s)

MS13 (16)

Anosyen domain

AM19 (09)

AM23 (09)

AM17 (12)

MS14 (05)

FOMA (36)

RUM4 (22)

RUM5 (21)

0 5 10 15 20 25

time(s)

MS15 (24)

Ikalamavony domain

MS16 (16)

AM16 (10)

AM18 (08)

0 5 10 15 20 25

time(s)

VOI (51)

Antananarivo domain

AM14 (10)

AM13 (08)

MS17 (16)

AM15 (07)

MS18 (08)

AM08 (06)

MS19 (20)

AM06 (11)

AM07 (14)

MS20 (16)

MS21 (11)

AM09 (10)

AM11 (02)

MS22 (16)

AM04 (07)

MS23 (24)

AM12 (10)

AM10 (06)

0 5 10 15 20 25

time(s)

MS01 (05)

MS02 (09)

MS03 (12)

MS04 (12)

LONA (12)

MS05 (10)

Cenozoic-Cretaceous

0 5 10 15 20 25

time(s)

MS06 (10)

Carboniferous-Jurassic

MS07 (12)

MS08 (12)

AM21 (08)

MS09 (13)

0 5 10 15 20 25

time(s)

MS24 (21)

Cretaceous volcanic

AM02 (02)

AM01 (07)

RUM2 (9)

RUM1 (14)

MAHA (14)

RUM3 (10)

0 5 10 15 20 25

time(s)

MS10 (20)

Androyen domain

MS11 (11)

AM20 (02)

AM22 (13)

MS12 (16)

0 5 10 15 20 25

time(s)

MS13 (16)

Anosyen domain

AM19 (09)

AM23 (09)

AM17 (12)

MS14 (05)

FOMA (36)

RUM4 (22)

RUM5 (21)

0 5 10 15 20 25

time(s)

MS15 (24)

Ikalamavony domain

MS16 (16)

AM16 (10)

AM18 (08)

0 5 10 15 20 25

time(s)

VOI (51)

Antananarivo domain

AM14 (10)

AM13 (08)

MS17 (16)

AM15 (07)

MS18 (08)

AM08 (06)

MS19 (20)

AM06 (11)

AM07 (14)

MS20 (16)

MS21 (11)

AM09 (10)

AM11 (02)

MS22 (16)

AM04 (07)

MS23 (24)

AM12 (10)

AM10 (06)

Direct wave at 0 s

Clear mid-crustaldiscontinuity (uppercrust/lower crust)

Clear but relatively weakMoho conversion andmultiples

Proterozoic:0 5 10 15 20 25

time(s)

MS01 (05)

MS02 (09)

MS03 (12)

MS04 (12)

LONA (12)

MS05 (10)

Cenozoic-Cretaceous

0 5 10 15 20 25

time(s)

MS06 (10)

Carboniferous-Jurassic

MS07 (12)

MS08 (12)

AM21 (08)

MS09 (13)

0 5 10 15 20 25

time(s)

MS24 (21)

Cretaceous volcanic

AM02 (02)

AM01 (07)

RUM2 (9)

RUM1 (14)

MAHA (14)

RUM3 (10)

0 5 10 15 20 25

time(s)

MS10 (20)

Androyen domain

MS11 (11)

AM20 (02)

AM22 (13)

MS12 (16)

0 5 10 15 20 25

time(s)

MS13 (16)

Anosyen domain

AM19 (09)

AM23 (09)

AM17 (12)

MS14 (05)

FOMA (36)

RUM4 (22)

RUM5 (21)

0 5 10 15 20 25

time(s)

MS15 (24)

Ikalamavony domain

MS16 (16)

AM16 (10)

AM18 (08)

0 5 10 15 20 25

time(s)

VOI (51)

Antananarivo domain

AM14 (10)

AM13 (08)

MS17 (16)

AM15 (07)

MS18 (08)

AM08 (06)

MS19 (20)

AM06 (11)

AM07 (14)

MS20 (16)

MS21 (11)

AM09 (10)

AM11 (02)

MS22 (16)

AM04 (07)

MS23 (24)

AM12 (10)

AM10 (06)

Direct wave at 0 s

Only weak conversionfrom within the crust

Distinct Moho conversionand (at some stations)multiples

Sedimentary basin:

0 5 10 15 20 25

time(s)

MS01 (05)

MS02 (09)

MS03 (12)

MS04 (12)

LONA (12)

MS05 (10)

Cenozoic-Cretaceous

0 5 10 15 20 25

time(s)

MS06 (10)

Carboniferous-Jurassic

MS07 (12)

MS08 (12)

AM21 (08)

MS09 (13)

0 5 10 15 20 25

time(s)

MS24 (21)

Cretaceous volcanic

AM02 (02)

AM01 (07)

RUM2 (9)

RUM1 (14)

MAHA (14)

RUM3 (10)

0 5 10 15 20 25

time(s)

MS10 (20)

Androyen domain

MS11 (11)

AM20 (02)

AM22 (13)

MS12 (16)

0 5 10 15 20 25

time(s)

MS13 (16)

Anosyen domain

AM19 (09)

AM23 (09)

AM17 (12)

MS14 (05)

FOMA (36)

RUM4 (22)

RUM5 (21)

0 5 10 15 20 25

time(s)

MS15 (24)

Ikalamavony domain

MS16 (16)

AM16 (10)

AM18 (08)

0 5 10 15 20 25

time(s)

VOI (51)

Antananarivo domain

AM14 (10)

AM13 (08)

MS17 (16)

AM15 (07)

MS18 (08)

AM08 (06)

MS19 (20)

AM06 (11)

AM07 (14)

MS20 (16)

MS21 (11)

AM09 (10)

AM11 (02)

MS22 (16)

AM04 (07)

MS23 (24)

AM12 (10)

AM10 (06)

Strongest peak fromsediment basementconversion, not directwave (at most stations)

‘Messier’ RF

Moho difficult to separatefrom sediment multiples

Page 41: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Working with less-than-perfect dataWhat can go wrong?

Multiples too weak, or scatteredin time

Cause Lateral heterogeneity(dipping boundary,small-scale heterogeneity),gradual transition

Consequence Result iscontrolled solely by Psconversion, perfect trade-off,need to assume VP/VS ratioto get H or vice versa.

Ambiguous phase identification

Cause Most prominentdiscontinuity might not bethe target one (e.g. Moho);

Consequence Misinterpretation.Completely wrongmeasurements notrepresentative of eitherdiscontinuity can result frominterference of multiples.

Precambrian crust - Madagascar [Rindraharisaona et al., 2017]

Well constrained Strong trade-off

Tilmann (GFZ,FUB) Receiver Functions 25 / 0

Page 42: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Working with less-than-perfect dataWhat can go wrong?

Multiples too weak, or scatteredin time

Cause Lateral heterogeneity(dipping boundary,small-scale heterogeneity),gradual transition

Consequence Result iscontrolled solely by Psconversion, perfect trade-off,need to assume VP/VS ratioto get H or vice versa.

Ambiguous phase identification

Cause Most prominentdiscontinuity might not bethe target one (e.g. Moho);

Consequence Misinterpretation.Completely wrongmeasurements notrepresentative of eitherdiscontinuity can result frominterference of multiples.

Synthetic example [Wolbern and Rumpker, 2017]Sharp Moho Transitional Moho

Tilmann (GFZ,FUB) Receiver Functions 25 / 0

Page 43: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Working with less-than-perfect dataWhat can go wrong?

Multiples too weak, or scatteredin time

Cause Lateral heterogeneity(dipping boundary,small-scale heterogeneity),gradual transition

Consequence Result iscontrolled solely by Psconversion, perfect trade-off,need to assume VP/VS ratioto get H or vice versa.

Ambiguous phase identification

Cause Most prominentdiscontinuity might not bethe target one (e.g. Moho);

Consequence Misinterpretation.Completely wrongmeasurements notrepresentative of eitherdiscontinuity can result frominterference of multiples.

Cretaceous volcanics - Madagascar [Rindraharisaona et al., 2017]

Upper crust - lower crust Moho

Tilmann (GFZ,FUB) Receiver Functions 25 / 0

Page 44: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Working with less-than-perfect dataWhat can go wrong?

Multiples too weak, or scatteredin time

Cause Lateral heterogeneity(dipping boundary,small-scale heterogeneity),gradual transition

Consequence Result iscontrolled solely by Psconversion, perfect trade-off,need to assume VP/VS ratioto get H or vice versa.

Ambiguous phase identification

Cause Most prominentdiscontinuity might not bethe target one (e.g. Moho);

Consequence Misinterpretation.Completely wrongmeasurements notrepresentative of eitherdiscontinuity can result frominterference of multiples.

Cretaceous volcanics - Madagascar [Rindraharisaona et al., 2017]

Upper crust - lower crust Moho

Tilmann (GFZ,FUB) Receiver Functions 25 / 0

Page 45: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Working with less-than-perfect dataWhat can go wrong?

Multiples too weak, or scatteredin time

Cause Lateral heterogeneity(dipping boundary,small-scale heterogeneity),gradual transition

Consequence Result iscontrolled solely by Psconversion, perfect trade-off,need to assume VP/VS ratioto get H or vice versa.

Ambiguous phase identification

Cause Most prominentdiscontinuity might not bethe target one (e.g. Moho);

Consequence Misinterpretation.Completely wrongmeasurements notrepresentative of eitherdiscontinuity can result frominterference of multiples.

Cretaceous volcanics - Madagascar [Rindraharisaona et al., 2017]

Upper crust - lower crust Moho

Tilmann (GFZ,FUB) Receiver Functions 25 / 0

Page 46: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile (Southern Madagascar)

Moho depth VP/VS ratio

44˚ 46˚ 48˚

-24˚

-22˚

-20˚

A

B

C

Archean

Proterozoic

Morondava basin

Volcanic

Br

Bg-Rn

Bg-Rn

Zz

If

If

Am

Ej

Cn

Cr Cb-Jr

Vb

Ad

An

Ik

ItAt

Ag

24

23

25

25

24 29

30

29

31 33

35

36 36 36

36

35

40 39

39 40

39

38

38

33

40

40

24

26

29

29

41 4040

40

41

38

38

39

36

38

38

38

37

38

39

36

34

31 35

35

30

29

31

38

37

36

33

35

20 25 30 35 40Moho Depth(km)

44˚ 46˚ 48˚

-24˚

-22˚

-20˚

A

B

C

Archean

Proterozoic

Morondava basin

Volcanic

Br

Bg-Rn

Bg-Rn

Zz

If

If

Am

Ej

Cn

Cr Cb-Jr

Vb

Ad

An

Ik

ItAt

Ag

1.85

1.82 1.80 1.82

1.81 1.80

1.78

1.73

1.76

1.81

1.78

1.72 1.75

1.76

1.78

1.82

1.69

1.75

1.75

1.76

1.76

1.73

1.73

1.98

1.70

1.81

1.97

1.82

1.81

1.67

1.781.74

1.76

1.71

1.761.79

1.751.76

1.69

1.71

1.77

1.81

1.72

1.69

1.71

1.76

1.78

1.77

1.76

1.94

1.80

1.96

1.69

1.69

1.72

1.82

1.68 1.72 1.76 1.80 1.84 1.88Vp/Vs ratio

Page 47: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile (Southern Madagascar)

44 45 46 47 48

−500

0

500

1000

1500

Ele

vati

on (

m)

−100

−50

0

50

100

Bouguer

anom

aly

(m

Gal)

Morondava basin Proterozoic Archean Volcanic

Elevation

Bouguer Anomaly

computed Bouguer Anomaly

44 45 46 47 48Longitude

15

20

25

30

35

40

Moho D

epth

(km

)

Cenozoic-CretaceousCarboniferious-Jurassic

Adro

yen

Anosyen BR

SZ

Ikala

mavony

AntananarivoCretaceousVolcanic

1.6

1.7

1.8

1.9

2.0

2.1

Vp/V

s

Moho

Vp/Vs

44 45 46 47 48Longitude

0

10

20

30

40

50

60

Depth

(km

)

Sediment Upper crust

Middle crust

Lower crust

Mantle

2.0

2.4

2.8

3.2

3.6

4.0

4.4

4.8

vs(

km/s

)

Contributions of crustallayers to bulk VP/VS

Interpretation

The recovered VP/VS represents an whole-crust average - it generally cannot be used to directlyidentify lithologies but needs to take into account the varying crustal layers but can inform onthe dominant bulk composition

NB The VP/VS ratio measurement is generally less reliable than Moho depth measurement

Page 48: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile (Southern Madagascar)

44 45 46 47 48

−500

0

500

1000

1500

Ele

vati

on (

m)

−100

−50

0

50

100

Bouguer

anom

aly

(m

Gal)

Morondava basin Proterozoic Archean Volcanic

Elevation

Bouguer Anomaly

computed Bouguer Anomaly

44 45 46 47 48Longitude

15

20

25

30

35

40

Moho D

epth

(km

)

Cenozoic-CretaceousCarboniferious-Jurassic

Adro

yen

Anosyen BR

SZ

Ikala

mavony

AntananarivoCretaceousVolcanic

1.6

1.7

1.8

1.9

2.0

2.1

Vp/V

s

Moho

Vp/Vs

44 45 46 47 48Longitude

0

10

20

30

40

50

60

Depth

(km

)

Sediment Upper crust

Middle crust

Lower crust

Mantle

2.0

2.4

2.8

3.2

3.6

4.0

4.4

4.8

vs(

km/s

)

Contributions of crustallayers to bulk VP/VS

Interpretation

The recovered VP/VS represents an whole-crust average - it generally cannot be used to directlyidentify lithologies but needs to take into account the varying crustal layers but can inform onthe dominant bulk composition

NB The VP/VS ratio measurement is generally less reliable than Moho depth measurement

Page 49: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile (Southern Madagascar)

44 45 46 47 48

−500

0

500

1000

1500

Ele

vati

on (

m)

−100

−50

0

50

100

Bouguer

anom

aly

(m

Gal)

Morondava basin Proterozoic Archean Volcanic

Elevation

Bouguer Anomaly

computed Bouguer Anomaly

44 45 46 47 48Longitude

15

20

25

30

35

40

Moho D

epth

(km

)

Cenozoic-CretaceousCarboniferious-Jurassic

Adro

yen

Anosyen BR

SZ

Ikala

mavony

AntananarivoCretaceousVolcanic

1.6

1.7

1.8

1.9

2.0

2.1

Vp/V

s

Moho

Vp/Vs

44 45 46 47 48Longitude

0

10

20

30

40

50

60

Depth

(km

)

Sediment Upper crust

Middle crust

Lower crust

Mantle

2.0

2.4

2.8

3.2

3.6

4.0

4.4

4.8

vs(

km/s

)

Contributions of crustallayers to bulk VP/VS

Interpretation

The recovered VP/VS represents an whole-crust average - it generally cannot be used to directlyidentify lithologies but needs to take into account the varying crustal layers but can inform onthe dominant bulk composition

NB The VP/VS ratio measurement is generally less reliable than Moho depth measurement

Page 50: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Outline

1 Introduction

2 Crustal Vp/Vs ratio and Moho depth from stacking of multiples

3 Common Conversion Point Stacks (CCCP)

Tilmann (GFZ,FUB) Receiver Functions 28 / 0

Page 51: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

CCCP - Basic principle

Geometry for P-RF S-RF

Assume conversions occur at subhorizontal interfaces

Write seismogram amplitudes into bins along expected ray path of converted phase

⇒ Ignores diffraction (equiv. to assuming specular reflection in reflection problems)

Tilmann (GFZ,FUB) Receiver Functions 29 / 0

Page 52: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Synthetic example – One-layer crust (Movie)Single earthquake

kpcrst

8

−1.0−0.8−0.6−0.4−0.20.0 0.2 0.4 0.6 0.8 1.0

Amplitude

0

100

200

Dep

th (k

m)

0 100 200

Distance (km)

MultiplesDiffraction

Tilmann (GFZ,FUB) Receiver Functions 30 / 0

Page 53: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Case study: SELASOMA profile Southern MadagascarP-RF - Rindraharisaona et al. [2017]

Colors represent discontinuities, not absolute velocities (here: red: sudden increase withdepth)

In PS stack, multiples cause artifacts at larger depths, in PpPs and PpSs stack, artifactsfrom direct conversion at shallower depths

CCCP stacks of multiples can give additional confidence

Tilmann (GFZ,FUB) Receiver Functions 31 / 0

Page 54: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P-RF vs S-RFExample: Himalaya-Tibet continental collision

P-RF (high frequency):

Nabelek et al. [2009]

Detailed images of the crustal interfaces and Moho. Deeperstructure obscured by multiples and not shown.

S-RF (low-frequency):

Zhao et al. [2010]

Only low-resolution Moho, nointernal crustal structure. Imagesmantle discontinuties, e.g. LAB(lithosphere-asthenosphereboundary)

Note that the cross-sections are not exactly from the same profile.

Tilmann (GFZ,FUB) Receiver Functions 32 / 0

Page 55: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P-RF vs S-RFExample: Himalaya-Tibet continental collision

P-RF (high frequency):

Nabelek et al. [2009]

Detailed images of the crustal interfaces and Moho. Deeperstructure obscured by multiples and not shown.

S-RF (low-frequency):

Zhao et al. [2010]

Only low-resolution Moho, nointernal crustal structure. Imagesmantle discontinuties, e.g. LAB(lithosphere-asthenosphereboundary)

Note that the cross-sections are not exactly from the same profile.

Tilmann (GFZ,FUB) Receiver Functions 32 / 0

Page 56: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

P-RF vs S-RF direct comparisonExample: North Chile subduction zone

Time section P-RF vs S-RF

Sodoudi et al. [2011]

For reference: P-RF CCCP

Tilmann (GFZ,FUB) Receiver Functions 33 / 0

Page 57: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

What can go wrong?Dipping interfaces [Schneider et al., 2013]

PRF - Pamir continental subduction

Because the assumption of conversion athorizontal interfaces, dipping structure areshown at too shallow dip (significant effect fordips>∼ 30◦)

CCCP stacking under assumption of dippinginterface images the steeply dipping structurecorrectly but will show horizontal interfaces(here the flat Moho) more shallow than inreality.

Tilmann (GFZ,FUB) Receiver Functions 34 / 0

Page 58: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Dipping interfacesSynthetic tests [Schneider et al., 2013]

Tilmann (GFZ,FUB) Receiver Functions 35 / 0

Page 59: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

What can go wrong?Dipping interfaces [Schneider et al., 2013]

PRF - Pamir continental subduction

Because the assumption of conversion athorizontal interfaces, dipping structure areshown at too shallow dip (significant effect fordips>∼ 30◦)

CCCP stacking under assumption of dippinginterface images the steeply dipping structurecorrectly but will show horizontal interfaces(here the flat Moho) more shallow than inreality.

Tilmann (GFZ,FUB) Receiver Functions 36 / 0

Page 60: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migration

Make no assumptions on smoothness or geometry of discontinuites/anomalies.Trace seismic energy to all possible locations where conversion might havehappened. ⇒ Constructive interference at real conversion points, destructiveinterference at all others.

[Rondenay, 2009]

Tilmann (GFZ,FUB) Receiver Functions 37 / 0

Page 61: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migrationComparing (horizontal) CCCP to migration

6 in-plane incident waves at different slownesses[Rondenay, 2009]Tilmann (GFZ,FUB) Receiver Functions 38 / 0

Page 62: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migration

However:

Requires very good information on velocitymodel:Correct velocity

Ryberg&Weber (2000)

Get frowns & smiles

Require a high density of receivers:

Sodoudi et al. [2011]

Otherwise: more smiles!

Tilmann (GFZ,FUB) Receiver Functions 39 / 0

Page 63: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migration

However:

Requires very good information on velocitymodel:Too slow:

Ryberg&Weber (2000)

Get frowns & smiles

Require a high density of receivers:

Sodoudi et al. [2011]

Otherwise: more smiles!

Tilmann (GFZ,FUB) Receiver Functions 39 / 0

Page 64: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migration

However:

Requires very good information on velocitymodel:Too fast:

Ryberg&Weber (2000)

Get frowns & smiles

Require a high density of receivers:

Sodoudi et al. [2011]

Otherwise: more smiles!

Tilmann (GFZ,FUB) Receiver Functions 39 / 0

Page 65: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migration

However:

Requires very good information on velocitymodel:Too fast:

Ryberg&Weber (2000)

Get frowns & smiles

Require a high density of receivers:

Sodoudi et al. [2011]

Otherwise: more smiles!

Tilmann (GFZ,FUB) Receiver Functions 39 / 0

Page 66: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migration

However:

Requires very good information on velocitymodel:Too fast:

Ryberg&Weber (2000)

Get frowns & smiles

Require a high density of receivers:

Sodoudi et al. [2011]

Otherwise: more smiles!

Tilmann (GFZ,FUB) Receiver Functions 39 / 0

Page 67: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

A more general approach: migration

However:

Requires very good information on velocitymodel:Too fast:

Ryberg&Weber (2000)

Get frowns & smiles

Require a high density of receivers:

Sodoudi et al. [2011]Otherwise: more smiles!

Tilmann (GFZ,FUB) Receiver Functions 39 / 0

Page 68: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Effect of gradual transitions and frequency dependence

Kind et al. [2012]

At long periods Moho peak shifted because of interference with intra-crustal (Conrad)discontinuity

Transitional discontinuity (here LAB) disappears

In addition to 1D effects shown, 2D - 3D effects can influence frequency dependence

Tilmann (GFZ,FUB) Receiver Functions 40 / 0

Page 69: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Not covered because of lack of time:

Waveform inversion (1D, 2D, 3D)

P - RF CCCP - discontinuities shown

Japan [Kawakatsu et al., 2009]

Inversion - actual velocity diffwrt reference shown

Cascadia [Rondenay, 2009]

Deconvolution methods and sidelobes

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Page 70: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

Summary (of sorts)

P receiver functions - high-to-medium frequency Crustal and slab imaging ⇒ CCCPimaging/migration with direct conversion, maybe supplementary use of multiplesAverage crustal velocities ⇒ H − κ-stackingDetailed crustal velocity model ⇒ 1D waveform inversion (in combination with surfacewave dispersion from ambient noise)‘Slab’ velocity model: ⇒ 2D, 3D waveform inversion

P receiver functions - medium-to-low frequency Target: Mantle transition zone (410, 660discontinuites) ⇒ Station or CCCP stacking with direct conversions)

S receiver functions - low frequency Mantle lithosphere imaging(lithosphere-asthenosphere-boundary (LAB) - mid-lithopheric discontinuities (MLD)

Pay attention to:

Artifacts from in- and out-of plane diffractions, processing

Separation of primaries from multiples

RF-methods sensitive to discontinuities not absolute velocities - subject to velocity-depthtradeoff!

Page 71: Introduction to the receiver function method · 2018. 2. 6. · 1Introduction. 2Crustal Vp/Vs ratio and Moho depth from stacking of multiples. 3Common Conversion Point Stacks (CCCP)

References I

R. C. Aster, B. Borchers, and C. H. Thurber. Parameter estimation and inverse problems. Elsevier, 1st edition,2005.

H. Kawakatsu, P. Kumar, Y. Takei, M. Shinohara, T. Kanazawa, E. Araki, and K. Suyehiro. Seismic evidencefor sharp lithosphere-asthenosphere boundaries of oceanic plates. Science, 324:499–502, 2009. doi:10.1126/science.1169499.

B. Kennett. The seismic wavefield, volume II: Interpretation of seismograms on regional and global scales.Cambridge University Press, 2002.

R. Kind and H. Yuan. Encyclopedia of Solid Earth Geophysics, chapter Seismic Receiver Function Technique,pages 1258–1269. Springer, 2011.

R. Kind, X. H. Yuan, and P. Kumar. Seismic receiver functions and the lithosphere-asthenosphere boundary.Tectonophysics, 536:25–43, April 2012. doi: 10.1016/j.tecto.2012.03.005.

C.A. Langston. Structure Under Mount Rainier, Washington, Inferred From Teleseismic Body Waves. J.Geophys.Res., 84:4749–4762, 1979.

D. Lombardi, Braunmiller J., E. Kissling, and D. Giardini. Moho depth and Poisson’s ratio in theWestern?Central Alps from receiver functions. Geophys. J. Int., 2008. doi:10.1111/j.1365-246X.2007.03706.x.

J. Nabelek, Hetenyi G., J. Vergne, S. Sapkota, B. Kafle, M. Jiang, H. Su, J. Chen, B. S. Huang, andHi-Climb-Team. Underplating in the Himalayan-Tibet collision zone revealed by the Hi-CLIMB experiment.Science, 325:1371–1374, 2009. doi: 10.1126/science.1167719.

E. J. Rindraharisaona, F. Tilmann, X. Yuan, G. Rumpker, J. Giese, G. Rambolamanana, and G. Barruol.Crustal structure of southern Madagascar from receiver functions and ambient noise correlation:Implications for crustal evolution. J. Geophys. Res., 122(2):1179–1197, 2017. doi:10.1002/2016jb013565.

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References II

S. Rondenay. Upper mantle imaging with array recordings of converted and scattered teleseismic waves. Surv.Geophys., 30:377–405, 2009. doi: 10.1007/s10712-009-9071-5.

F. M. Schneider, X. Yuan, B. Schurr, J. Mechie, C. Sippl, C. Haberland, V. Minaev, I. Oimahmadov,M. Gadoev, N. Radjabov, U. Abdybachaev, S. Orunbaev, and S. Negmatullaev. Seismic imaging ofsubducting continental lower crust beneath the pamir. Earth Planet. Sci. Let., 375:101–112, 2013. doi:10.1016/j.epsl.2013.05.015.

F. Sodoudi, X. Yuan, G. Asch, and R. Kind. High?resolution image of the geometry and thickness of thesubducting nazca lithosphere beneath northern Chile. J. Geophys. Res., 116:B04302, 2011. doi:10.1029/2010JB007829.

TRANSALP Working Group. First deep seismic reflection images of the eastern alps reveal giant crustalwedges and transcrustal ramps. Geophys. Res. Let., 29, 2002. doi: 10.1029/2002GL014911.

L. P. Vinnik. Detection of waves converted from P to SV in the mantle. Phys. Earth Planet. Int., 15:39–45,1977.

I. Wolbern and G. Rumpker. Limitations of h − κ stacking: ambiguous results caused by crustal layering. J.Seismol., 21:221–235, 2017. doi: 10.1007/s10950-016-9599-z.

Junmeng Zhao, Xiaohui Yuan, Hongbing Liu, Prakash Kumar, Shunping Pei, Rainer Kind, Zhongjie Zhang,Jiwen Teng, Lin Ding, Xing Gao, Qiang Xu, and Wei Wang. The boundary between the Indian and Asiantectonic plates below Tibet. Proc. Nat. Acad. Sci., 107(25):11229–11233, 2010. doi:10.1073/pnas.1001921107.

L. Zhu. Crustal structure across the San Andreas Fault, Southern California from teleseismic converted waves.Earth Planet. Sci. Let., 179:183–190, 2000.

L. Zhu and H. Kanamori. Moho depth variation in southern California from teleseismic receiver functions. J.Geophys. Res., 105(B2):2969–2980, 2000.

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