Modulation de l'énergie sismique par la marée

Présentation d'Eric Beucler (LPG Nantes) aux 2èmes Rencontres Scientifiques et Techniques Résif | 12-14 octobre 2015, La Grande Motte

Transcript

1. Modulation de l’énergie sismique par la marée Éric Beucler, Antoine Mocquet, Martin Schimmel, Sébastien Chevrot, Jérôme Vergne, Matthieu Sylvander, Pierrick Gernigon & Olivier Quillard† eric.beucler@univ-nantes.fr Laboratoire de Planétologie et Géodynamique Observatoire des Sciences de l’Univers Nantes Atlantique /data/eric/img/logo/logoresifquadri.jpg PYROPE Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 1 / 17
2. The seismic signal, the seismic noise and vice-versa 2015 Oct 06 20:41:49 4˚W 4˚W 2˚W 2˚W 0˚ 0˚ 46˚N 47˚N 48˚N 49˚N 50˚N −400 −350 −300 −250 −200 −150 −100 −50 0 50 100 150 200 250 300 350 400 Altitude (m) NANTES LA ROCHELLE BREST RENNES CAEN LA ROCHE/YON SAINT−BRIEUC LE MANS SAINTES ANGOULÊME ANGERS NIORT POITIERS LORIENT VANNES CARHAIX PY41 PY42 PY43 PY44 PY45 PY45A PY46 PY47 PY48 PY49 CEA/DASE (LB+CP) RESIF−CLB PYROPE/VIBRIS 24 h of the Earth’s surface displacement (Feb. 26th, 2012) at PY43 (ANR PYROPE). Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 2 / 17
3. The seismic signal, the seismic noise and vice-versa 24 h of the Earth’s surface displacement (Feb. 26th, 2012) at PY43. Which part of the seismic signal is interesting? Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 3 / 17
4. The seismic signal, the seismic noise and vice-versa The seismic signal/noise: temporal vs spectral. Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 4 / 17
5. The seismic signal, the seismic noise and vice-versa Spectral estimate of the continuous seismic energy over 24h at TAM (http://geoscope.ipgp.fr). The microseismic noise Wiechert (1904) Linke (1909) Gutenberg (1931) Bernard (1941) Longuet-Higgins (1950) Hasselmann (1963) Burg & Burrell (1967) Haubrich & Mc Camy (1969) Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 5 / 17
6. The microseismic noise Primary peak (PM) period ∼11-16 s oceanic waves on the shores less energetic comparatively Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 6 / 17
7. The microseismic noise Secondary peak (SM) period ∼2-12 s constructive interferences of almost opposing waves much more energetic a In the open ocean (moving storm) b Near the coastlines c In the open ocean (simultaneous storms) Ardhuin et al. (2011) Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 7 / 17
8. Short-duration PSD Coastal and continental seismic stations (+buoy data +tidal ranges) window length 360 s (with overlap 60 s) → SR @ 0.8333 mHz (1 point every 20’) PY48 PY41 Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 8 / 17
9. Short-duration PSD Coastal and continental seismic stations (+buoy data +tidal ranges) - vertical component Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 9 / 17
10. Short-duration PSD Coastal and continental seismic stations (+buoy data +tidal ranges) - North/South component Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 10 / 17
11. Short-duration PSD variations PY41 vertical component Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 11 / 17
12. Short-duration PSD variations PY41 vertical component Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 11 / 17
13. Short-duration PSD variations PY41 vertical component PY41 vertical component. a. Time PSD variations, b. Spectral PSD variations. Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 11 / 17
14. Short-duration PSD variations PY41 vertical component PY41 vertical component. a. Time PSD variations, b. Spectral PSD variations. Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 11 / 17
15. Short-duration PSD variations PY41 vertical component PY41 vertical component. a. Time PSD variations, b. Spectral PSD variations. Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 11 / 17
16. Short-duration PSD variations Sea level near PY41. PY41 vertical component. a. Time PSD variations, b. Spectral PSD variations. Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 11 / 17
17. Short-duration PSD variations M2 modulations are computed for all components at PY41, PY48, VAL and ECH between 0.014 and 0.2 Hz (2-70 s period). Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 12 / 17
18. Tracking SM sources Short-duration PSD vs numerical wave models (http://www.previmer.org). Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 13 / 17
19. Tracking SM sources Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 14 / 17
20. Summary North Atlantic seismic noise sources Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 15 / 17
21. Summary Coastal and inland stations Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 16 / 17
22. Summary The SM energy (∼2-12 s) is generated in shallow waters (shores) and in the deep ocean; can be due to multiple and simultaneous sources; is time/frequency dependent due to the swell period variations (over a day/week/year?); is location dependent due to attenuation; depends on the coupling efficiency between water depth column and solid ground; depends on the site quality (geology) beneath the receivers. Very simple process indeed. . . work in progress More details in Beucler, É., A. Mocquet, M. Schimmel, S. Chevrot, O. Quillard, J. Vergne & M. Sylvander (2014). Observation of deep water microseisms in the North Atlantic Ocean using tide modulations. Geophys. Res. Lett., 2014GL062347. Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 17 / 17
23. Summary Coastal and continental seismic stations (+buoy data +tidal ranges) - East/West component Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 17 / 17
24. Short-duration PSD variations Buoy data Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 17 / 17
25. Short-duration PSD variations Normalized M2 modulations for all components at PY41, PY48, VAL and ECH between 0.014 and 0.2 Hz (2-70 s period). Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 17 / 17
26. Tracking SM sources Short-duration PSD vs numerical wave models (http://www.previmer.org). Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 17 / 17
27. Microseism sources Éric Beucler (LPG) Tidal modulation of the seismic energy JST RESIF (13 oct. 2015) 17 / 17