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Teleseismic Event with Depth Phases

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Presentation on theme: "Teleseismic Event with Depth Phases"— Presentation transcript:

1 Teleseismic Event with Depth Phases

2 Honshu (Japan), 23.10.2004, Mb=6.8 Mainshock (6.8) aftershock 1 (6.4)

3 Records of Gräfenberg Array Honshu (Japan), 23.10.2004, Mb=5.8

4 Result of f-k Analysis Slowness: 4.57 Azimuth: 45°

5 Beam forming P pP depth = 21 km

6 Records of GRSN Honshu (Japan), 23.10.2004, Mb=5.8

7 Plane-wave Method

8 Lokalisierungen: SZGRF NEIC (USA) Historical Seismicity

9 Long Period Filter (SRO-LP):
T = 21.6 s, A = nm  MS = 6.8 Calculation of surface wave magnitude: MS = log (A/T)max log D for 18s < T < 22s body waves surface waves

10 Core phase distance range
(100° – 180°)

11 Body and core phases

12 Long-period filtered (SRO_LP simulation) three-component seismogram from an earthquake at PAPUA NEW GUINEA on July 17, 1998 recorded at station GRA1 in Germany at an epicentral distance of 117.5°. The horizontal components (RT) are rotated into the epicentral direction. Phases Pdiff, PP SP, SKS, SKKS, PS, Sdiff, SS and SSS are denoted.

13 outer core: PKPbc: 145° - 153° PKPab: 145° - 177° inner core: PKPdf: 122° - 180° core-mantle boundary: Pdiff: 98° - 144°

14 Core phases: PKPdf, PKPbc and PKPab

15

16 Short-period filtered (WWSSN_SP simulation) seismogram recorded at 9 GRSN stations from an earthquake in the Fiji Islands region at a depth of 643 km on September 30, (mb 5.1). All traces are shifted and aligned with respect to PKPdf and sorted according to distance. The epicentral distance for CLL is 148.4 and for the most distant station BFO . Core phases PKPdf, PKPbc and PKPab are easy to analyse in this distance range. Traveltime curves allow the epicentral distance to be determined with an precision of better than 1.

17 Fig Left: Records of the direct core phases PKPdf, PKPbc and PKPab as well as of the diffracted phase PKPdif from a Kermadec Island earthquake at stations of the GRSN in the distance range between 153° and 159°; right: ray paths through the Earth and along a map view of the Earth surface.

18 Slowness and raypaths of PKP phases

19 Core Phases Body waves in mantle Slowness > 4.5 Body waves in core
Different branches of PKP phase: e.G. at an epicentral distance of 150° PKPdf  Slowness ~ 1.6 s/° PKPbc  Slowness ~ 2.6 s/° PKPab  Slowness ~ 4.1 s/°

20 Aufzeichnung des GRSN Netzes Fiji Islands, 23.11.2004, Mb=5.9

21 Aufzeichnung des GRSN Netzes Fiji Islands, 23.11.2004, Mb=5.9

22 Aufzeichnung des GRSN Netzes Fiji Islands, 23.11.2004, Mb=5.9

23 Lokalisierungen:

24 Aufzeichnung des GRSN Netzes Fiji Islands, 23.11.2004, Mb=5.9
Tiefenphase pPKPbc identifiziert und gepickt  Tiefe: 550 km

25 Late and very late core phases

26 First onsets (P or PKP) -- Reflected phases -- Ray paths

27 First onsets (P or PKP) -- Reflected phases nPKP -- Ray paths


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