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Passive seismic reflection imaging, on the earth and on the moon Kees Wapenaar Delft University of Technology.

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Presentation on theme: "Passive seismic reflection imaging, on the earth and on the moon Kees Wapenaar Delft University of Technology."— Presentation transcript:

1 Passive seismic reflection imaging, on the earth and on the moon Kees Wapenaar Delft University of Technology

2 Structural trends in the subsurface of the Netherlands, with recent sources of seismicity (white circles) and contours of constant depth of the Mohorovic discontinuity (Beekman and Stephenson).

3 25% of antennas in central core High speed data transport Antenna cluster (Station) Central processor X Lofar / Persimmon (Permanent Seismic Imaging and Monitoring Network)

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5 Test-site Exloo

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7 Experiments for optimal receiver responses Experiments for optimal receiver responses Zoomed-in dynamite recordings at : - 12.5 m (left) - 6.25m (middle) - surface (right)

8 Lofar / Persimmon (Permanent Seismic Imaging and Monitoring Network) Partners: Delft University of Technology Free University of Amsterdam Utrecht University TNO-NITG KNMI NAM Shell MIT

9 Lofar / Persimmon (Permanent Seismic Imaging and Monitoring Network) Delft University of Technology Seismic Interferometric Imaging

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11 Cross-correlation

12 Cross-correlation result is equal to impulsive reflection response

13 Cross-correlation

14 Simplifying assumptions: Direct arrival at x A correlated with primary at x B Single diffractor Primaries only x A is the specular reflection point

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18 1500 m/s 2000 m/s

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21 Cross-correlation > one virtual source Repeat for all receivers > many virtual sources Imaging

22 Applications Persimmon Basin analysis Global seismology Lunar seismology ?

23 Artist impression of reflection imaging of global seismology data

24 receiver array traveltime tomography Cross-correlation of transmission responses source array reflection imaging Artist impression of reflection imaging of global seismology data

25 Applications Persimmon Basin analysis Global seismology Lunar seismology ?

26 Here is a bit of background on the seismology of Moonquakes. The info comes from the book "EARTHQUAKES" by G.A. EIBY the retired superintendant of the New Zealand Seismological Observatory in Wellington city.

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28 Three causes of lunar seismicity: Impacts Shallow: 0-60 km (crustal stresses) Deep : 600 – 900 km (tidal forces) Features: ‘High’ frequency (0.1 – 1.0 Hz) Small amplitudes (0.5 – 1.3 Richter) Low damping Long reverberations (~ 60 minutes)

29 VectorSeis ® Digital Sensor - No tilt limitations

30 Frequency Response Geophone & VectorSeis ® simultaneously shaken, table motion measured by Laser Vibrometer, Geophone and VectorSeis outputs normalized to Vibrometer -30 -25 -20 -15 -10 -5 0 5 -30 -25 -20 -15 -10 -5 0 5 110100 Frequency (Hz) Amplitude Response in dB VectorSeis sensor maintains dynamic range at extreme low frequencies Laser Vibrometer Geophone VectorSeis

31 Applications Persimmon Basin analysis Global seismology Lunar seismology ?


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