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Passive seismic reflection imaging, on the earth and on the moon Kees Wapenaar Guy Drijkoningen Deyan Draganov Elmer Ruigrok Delft University of Technology
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25% of antennas in central core High speed data transport Antenna cluster (Station) Central processor X Lofar: LOw Frequency ARray
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Combined monitoring the universe and the subsurface: Different applications; shared infrastructure
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25% of antennas in central core High speed data transport Antenna cluster (Station) Central processor X Permanent Seismic Imaging and Monitoring Network Lofar / Persimmon
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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).
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Test-site Exloo
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Hydrophones: Records of 8 seconds, Groups of 12 put next to each other Time: 30 May 2005, 15:36:45 GMT Magnitude: 2.3 Location (KNMI estimate): RD(x,y)=(243,595)
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Horizontal_x Geophone: Records of 8 seconds, Groups of 24 put next to each other Time: 30 May 2005, 15:36:45 GMT Magnitude: 2.3 Location (KNMI estimate): RD(x,y)=(243,595)
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Vertical Geophone: Records of 8 seconds, Groups of 24 put next to each other Extra filter 5-10 Hz to compensate for different characteristic with hydrophone Time: 30 May 2005, 15:36:45 GMT Magnitude: 2.3 Location (KNMI estimate): RD(x,y)=(243,595)
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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
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Lofar / Persimmon (Permanent Seismic Imaging and Monitoring Network) Delft University of Technology Seismic Interferometric Imaging
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1500 m/s 2000 m/s
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1500 m/s 2000 m/s
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1500 m/s 2000 m/s
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1500 m/s 2000 m/s
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Cross-correlation > one virtual source Repeat for all receivers > many virtual sources Imaging
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Seismic Interferometry Cross-correlation of received signals Man-made or natural sources (noise or transients) Differences with astronomy: Strongly inhomogeneous propagation model No far field assumptions Absolute instead of relative receiver positions Reflection instead of source imaging
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Applications Persimmon Basin analysis Global seismology Lunar seismology
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Interpretation
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Applications Persimmon Basin analysis Global seismology Lunar seismology
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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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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)
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VectorSeis ® Digital Sensor - No tilt limitations
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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
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Applications Persimmon Basin analysis Global seismology Lunar seismology
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