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1The Nature of the Global Wavefield
Illustration of the development of the seismic wavefield using examples from the great shallow
earthquake in Peru in June 2001, and an intermediate depth event (114 km) in Vanuatu in January 2001.
• wavefront diagrams for body waves and surface waves
• observations of long period seismograms from Geoscope stations
• synthetic seismogram simulations of shallow and deep sources
• global record sections (3-component) of the major phases
1
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P
PKP
PKIKPPKiKP
S
SKIKS
SKS
SKiKS
Figure 1.1. Ray paths from the Peru event for major P and S phases traced through the ak135 model
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600. 1200.Time [s]
Pn Sn Z
R PEL 17.03˚
T
P PnPn S SnSn Z
R SPB 25.67˚
T
P PnPn S SnSn LR
LQ
Z
R HDC
28.07˚
T
P PnPn PcP
S SnSn Z
R FDF
33.18˚
T
Figure 1.2. Three-component broad-band records from the 2001 vi 23 Peru event, rotated to the great circle direction,at stations with epicentral distances less than 35◦: (a) PEL (Peldehue, Chile), 17.03◦; (b) SPB (Sao Paulo, Brazil), 25.67◦;(c) HDC (Heredia, Costa Rica), 28.07◦; (d) FDF (Fort de France, Martinique), 33.18◦. The expected phase arrival timesfrom the ak135 model are indicated.
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600. 1200. 1800. 2400. 3000.
Time [s]
P PP S SS
LQ
LR
Z
R SCZ 69.24˚
T
P PP S SKSAC SS
LR
LQ
Z
T
R PPT 72.17˚
P PP SKSACS
SS
LR
LQ
Z
R KIP 90.76˚
T
P PP SKSACS SP
SS
LR
LQ
Z
R SSB 93.33˚
T
Figure 1.3. Three-component long-period records from the 2001 vi 23 Peru event, rotated to the great circle direction,at stations with epicentral distances from 65◦ to 95◦: (a) SCZ (Santa Cruz, California), 69.24◦; (b) PPT (Papeete, Tahiti),72.17◦; (c) KIP (Kipapa, Hawaii), 90.76◦; (d) SSB (Saint Saveure, France), 93.33◦. The expected phase arrival times fromthe ak135 model are indicated.
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1200. 1800. 2400. 3000. 3600.
Time [s]
Pdiff PKiKP PP
SKSACSKKSAC
Sdiff SP
SS
LR
LQ
Z
R NOUC
110.00˚
T
Pdiff PKiKP PP SKPDF
SKSACSKKSAC
SP SS
LR
LQ
Z
R CAN
114.69˚
T
Pdiff PKPDFPP SKPDF
SKSACSKKSAC
SP SS
LR
LQ
Z
R RER
117.97˚
T
PKPDFPP PKKPDF
SKKSACSKKPDF
SS Z
R INU 146.68
T
Figure 1.4. Three-component long-period records from the 2001 vi 23 Peru event, rotated to the great-circle direction,at stations with epicentral distances between 110◦ and 147◦: (a) NOUC (Noumea, New Caledonia), 110.00◦; (b) CAN(Canberra, Australia), 114.69◦; (c) RER (Reunion, Indian Ocean), 117.97◦; (d) INU (Inuyama, Japan), 146.68◦. The expectedphase arrival times from the ak135 model are indicated.
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P PP
SSS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PS
ICB
CMB
Figure 1.5. Wavefronts from the Peruvian event at 180 s after source initiation, body waves in cross-section at the leftand the wavefronts at the surface including the Rayleigh and Love waves at the right. The epicentre is indicated by across.
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PPP
SSS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PPcP
PP
PK
SPS
PcS
360 s
PPcP
PP
PK
SPS
PcS
Figure 1.6. Wavefronts for the Peruvian event at 360 s after source initiation, together with a snapshot of the wavefieldfrom a numerical simulation.
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P
PPPPP
PcP
S
SS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PPcP
PP
PKPKI
PKiK
SScSPS
PcS SK
ScP
Figure 1.7. Wavefronts from the Peruvian event at 540 s after source initiation, body waves in cross-section at the leftand the wavefronts at the surface including the Rayleigh and Love waves at the right.
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P
PPPPP
PcP
PcS
S
SS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
P
PP
PKPKIK
PKiK
S
ScS
SK
PcS ScP
720 s P
PP
PK
S
ScS
SK
ScP
Figure 1.8. Wavefronts for the Peruvian event at 720 s after source initiation, together with a snapshot of the wavefieldfrom a numerical simulation.
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PPPPP
S
SSFDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
(PcP)2
PP
PK
PPP
S
SSScS
PS
PPS
PcPS
SKiK
SK
SKK
SKI
PKS
Figure 1.9. Wavefronts from the Peruvian event at 900 s after source initiation, body waves in cross-section at the leftand the wavefronts at the surface including the Rayleigh and Love waves at the right.
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PPPPP
S
SSScS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PKKPP
PPP
PKP
S
SS
ScSS
SKS
SKKS
SK
SKKPS
PKS
SKP
PcPScS
PPS
1080 s
PP
PPP
PKP
PcPK
S
SS
ScSS
SKS
SKKS
SK
SKKPS
PKS
SKP
Figure 1.10. Wavefronts for the Peruvian event at 1080 s after source initiation, together with a snapshot of the wavefieldfrom a numerical simulation.
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PPP
S
SS
SSS
SKSScS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PKPP
PKK
PP
PPP
S
SS
ScSS
SKS
SKKS
PPS
SKK
PKS SKP
Figure 1.11. Wavefronts from the Peruvian event at 1260 s after source initiation, body waves in cross-section at theleft and the wavefronts at the surface including the Rayleigh and Love waves at the right.
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S
SS
SSS
SKSScS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PKK
PP
PPPPKPP
SS
SSS
SKS
SKKS
(ScS)2
SKK
PKPS
SKSP
1440 s
PP
PPPPKPP
SS
SSS
SKS
SKKS
(ScS)2
SKK
SKSP
Figure 1.12. Wavefronts for the Peruvian event at 1440 s after source initiation, together with a snapshot of the wavefieldfrom a numerical simulation.
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SS
SSS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PKK
PKKP
PPP
PKPPK
SS
SSS
SKKS
(ScS)2
SKK
Figure 1.13. Wavefronts from the Peruvian event at 1620 s after source initiation, body waves in cross-section at theleft and the wavefronts at the surface including the Rayleigh and Love waves at the right.
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SS
SSS
FDFHDC
KIP
PEL
PPT
SCZ
SPB
SSB
PKKP
PKPPKSS
SSS
SKKS
SKSS
SKK
1800 s(ScS)2K
SS
SSS
SKKS
Figure 1.14. Wavefronts for the Peruvian event at 1800 s after source initiation, together with a snapshot of the wavefieldfrom a numerical simulation.
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ATDFDFHDC
PEL
SCZ
SPB
SSB
FDF
HDC
KIP
NOUC
PEL
PPT
SCZ
SPB
Figure 1.15. Wavefronts for the surface waves at 2160 s (36 min).
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ATDFDFHDC
PEL
SCZ
SPB
SSB
FDF
HDC
KIP
NOUC
PEL
PPT
SCZ
SPB
Figure 1.16. Wavefronts for the surface waves at 2700 s (45 min).
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ATD
CAN
INU
NOUCRER
Figure 1.17. Wavefronts for the surface waves at 3600 s (60 min).
