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NEAREST Meeting 9-10 Oct., 2008 - Berlin

NEAREST - WP4 Tsunami signal detection.

brooke-mueller
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NEAREST Meeting 9-10 Oct., 2008 - Berlin

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  1. NEAREST - WP4 Tsunami signal detection Leader: INGV Team: Laura Beranzoli*, Gianfranco Cianchini*, Francesco Chierici^, Mariagrazia De Caro*, Davide Embriaco*, Paolo Favali*, Francesco Frugoni*, Nadia Lo Bue*, Giuditta Marinaro*, Stephen Monna*, Luca Pignagnoli^, Tiziana Sgroi** INGV^ISMAR NEAREST Meeting 9-10 Oct., 2008 - Berlin

  2. WP4 - Tsunami signal detection Objectives To carry out geophysical and oceanographic measurements on the seafloor and in the water column in the nearby of near-shore tsunamigenic sources for the identifications of tsunami signals. To operate deep seafloor multiparameter observatory of GEOSTAR type, developed in previous EC projects, in order to perform measurements on the seafloor and in the water column.

  3. Partners involved in WP4 ISMAR-BO. FFCUL, CSIC  selection of the marine site for the pilot experiment and characterisation on the basis of the knowledge of the area ISMAR-BO cruises responsible AWI, UGR, IM  requirements of sensor sampling rates TFH  MODUS for the pilot experiment (deployment/recovery) INGV  Seafloor observatory (GEOSTAR)

  4. Sensors Effic. 100% 100% 0%* 99,8% 100% 100% 100% 100% 98% * failed

  5. GEOSTAR Tsunameter prototype Tsunami Detection automatic Algorithm is based on the continuous analysis of seismometer (broad-band, 3-comp., 100 Hz) and pressure sensor (Absolute Pressure Gauge, APG) measurements • Mission mode: normal acquisition, APG @ 1 sample/15 s (data storage, periodic messages) • Event mode: event messages, higher pressure sampling rate (1 sample/5 s)

  6. Mission Mode: periodic messages

  7. Event Detection Performance between 25 Aug. ’07 and 6 July ’08, 175 pressure and 502 seismic event messages generated (total 677) For each event GEOSTAR was able to: • Change Pressure acquisition rate (from 15 to 5 sec) generate and store pressure event data file (success 100% of expected event files) • Prepare event messages to be sent (success 100% of expected event files) • Each message file was filled with expected information on event (100%)

  8. Pressure Data from APG • 1290900 pressure measurements (~224 days) @15s • 455091 samples @ 5s (632 hours) in event mode • Efficiency: 99,8 %

  9. Pressure first data quality check • Pressure signal derivative (absolute value) Aug Sept Oct Nov Dec Jan Feb Mar Detected Pressure Events 0 166 8 1 2 5

  10. September ‘07 January ‘08

  11. Pressure Event detection • 175 pressure events mostly due to pressure sensor (test in real conditions) • 8 events during January-April 2008: - 4 Jan at 8:50 and 11:40 • 7 March from 22:15 to 8 March 6:30 (5 events) • 11 March 19:10

  12. 4 Jan 08 pressure event

  13. 4 Jan 08, 8:50h

  14. 4 Jan 08, 11:40h

  15. Pressure signal from 2 to 6 Jan 2008 120s 2 hours tsunami band High frequency noise (@ 30 s, see derivative signal)

  16. Gravity data: 3,4,5,8 Jan 2008 Period (s) 1000 100 10 tsunami band 5 Jan 3 Jan 4 Jan 8 Jan

  17. Comparison between APG and OBS25 (hydrophone)

  18. OBS25 H power spectrum3-6 Jan 2008 Period (s) 10 100 1000 tsunami band 4 Jan 5 Jan 6 Jan 3 Jan

  19. 4 Jan 08 pressure event • APG: high value of 4 Jan. power spectrum with respect to 3 and 5 Jan. • OBS25 (hydr.) and gravity-meter: analogous increase of power spectrum • Power spectrum increase in 50-1000 s band TDA detects tsunamis in the band 120-7200 sec.  TDA correctly declared EVENT

  20. DATA FORMAT, TIME CORRECTION AND COMPONENT ORIENTATION GEOSTAR SEISMOLOGICAL INSTRUMENTS GURALP CMG-40T 3 component broadband seismometer (30 s-50 Hz)‏ GURALP CMG-5T 3 component broadband accelerometer, strong motion (DC-100 Hz)‏ OAS E-2PD- Hydrophone 0- 5KHz 100 Hz sampling, 7 channels 24 bit + 3 mass channels 16 bit GURALP DM-24 Digitizer, 7 channels at 24 bit + 3 auxiliary OBS mass channels at 16 bit synchronization from SERCEL rubidium clock- input in GPS DM-24 channel + Gravitymeter samples at 1s

  21. DATA FORMAT, TIME CORRECTION AND COMPONENT ORIENTATION How was the drift measured After GEOSTAR recovery, on the ship, a date-time request to the rubidium clock was accomplished through a direct link via serial port: the response to the request was August, 19th 20:15:21, the current time. The drift was measured by standard procedures. A drift of 184 ms over almost 1 year was measured. The drift value agreed with values from previous experiments.

  22. SAMPLE OF RECORDED EVENTS Some statistics on the data analyzed so far on 97 days inspected: LOCAL + some REGIONAL EVENTS M > 1.2 RECORDED 57 Epic Areas: Golfo de Cadiz, Gorringe, SW Cabo S. Vicente, SW Albufeira, Mar de Marrocos. Reference bulletin: Boletim Sismologico Preliminar do Continente e Madeira (IMP)‏ TELESEISM M > 6 RECORDED 5 Reference bulletin: NEIC (hypocentral parameters)‏ Boletim Sismologico Preliminar do Continente e Madeira (IMP)

  23. SAMPLE OF RECORDED EVENTS Events recognized so far by GEOSTAR in 97 days

  24. SAMPLE OF RECORDED EVENTS EXAMPLE OF GEOSTAR EVENT TABLE

  25. WAVEFORMS AND PHASE RECOGNITION Origin Time 7/5/2008 15:12:56.66 Ml 3.5 Gorringe Bank P S 2 sec

  26. WAVEFORMS AND PHASE RECOGNITION Ml 3 Origin Time 07:41:42.9 Mar de Marrocos 4 – 12 Hz Time [s]

  27. WAVEFORMS AND PHASE RECOGNITION M 3.6 (MAR) SW Alhucemas example of T-phase from regional event 4 – 12 Hz Time [s]

  28. WAVEFORMS AND PHASE RECOGNITION M 6.9 Origin Time 09:38 Northern Mid-Atlantic Ridge Time [s] 0.5 – 2 Hz

  29. WAVEFORMS AND PHASE RECOGNITION M 6.2 Origin Time 05:14:37.2 Southern Greece Time [s] 0.5 – 2 Hz

  30. COMPARISON WITH OTHER INSTRUMENTS M 4.7 Origin Time 00:21:42.5 W of Gibraltar GEOS OBS ACC

  31. COMPARISON WITH OTHER INSTRUMENTS P arrival M 4.7 Origin Time 00:21:42.5 W of Gibraltar OBS ACC

  32. COMPARISON WITH OTHER INSTRUMENTS ACC Time [s]

  33. COMPARISON WITH OTHER INSTRUMENTS Ml 3.0 Origin Time 05:13:27.06 W GIBRALTAR EMSC ACC 4 – 25 Hz Time [s]

  34. COMPARISON WITH OTHER INSTRUMENTS Mw 7.7 Origin time 02:12:04.50 Sea of Okhotsk OBS25 GEOS OBS 5 s DT ~ 1.3 s

  35. COMPARISON WITH OTHER INSTRUMENTS Mw 6.4 Origin Time 12:35:30 Greece GRAV 2000 s

  36. COMPARISON WITH OTHER INSTRUMENTS Mw 7.7 Origin time 02:12:04.50 Sea of Okhotsk GRAV 0.05 – 0.3 Hz 1000 s

  37. DATA AND PROBLEMS Cleaning Seismological signals from disturbances OBS ACC H Time 100 s

  38. DATA AND PROBLEMS Origin Time 23/5/2008 11:39:11.90 Ml 2.1 SW Cabo S.Vicente P D2:1hz noise D1 144 sec. Trouble final part S 10 s

  39. DATA AND PROBLEMS Zoom of Ml 1.9 Origin time 05:01:46.10 Gorringe D2 4-12 Hz Time [s]

  40. REMEDIAL ACTIONS Dry test at Porto Marghera D1 (large disturbance) re-created in Lab. digitally Disturbance D2 (1 Hz frequency) Electronics origin Sensors + problem description to GURALP Problem is being solved by TECNOMARE further testing necessary Cause of D1 recognized: interrupt control line of levelling platform too sensitive to noise due to small capacitor Solution: increase capacitance 100 times Sensors sent to TECNOMARE Tests with all GEOSTAR system in mission mode before next deployment in Gulf of Cadiz (late May 2009)

  41. Sample 1 Sample 1 Sample 1 FIRST ATTEMPTS TO CLEAN THE SIGNAL Correction Stage Methods: 1/2“deterministic method for D1”

  42. FIRST ATTEMPTS TO CLEAN THE SIGNAL “deterministic method”Sample 1 - fit Fitting result A = 1.46e+6 +/- 9e+4 (6.179%)‏  = 0.0426 +/- 0.0014 (3.275%)‏ = 0.0320 +/- 0.0013 (4.058%)

  43. FIRST ATTEMPTS TO CLEAN THE SIGNAL “deterministic method”Sample 2 Sample 2

  44. FIRST ATTEMPTS TO CLEAN THE SIGNAL Deterministic Correction Summary A = 1.46e+6 +/- 9e+4 (6.179%)‏ = 0.0426 +/- 0.0014 (3.275%)‏  = 0.0320 +/- 0.0013 (4.058%) Sample 1 A = 1.46e+6 +/- 5e+4 (3.926%)‏ = 0.04309 +/- 0.0009 (2.124%)‏  = 0.0326 +/- 0.0008 (2.543%) Sample 2 A = 3.9e+6 +/- 1.9e+5 (4.879%)‏ = 0.0414 +/- 0.0011 (2.646%)‏ = 0.0321 +/- 0.0010 (3.198%) Sample 3

  45. FIRST ATTEMPTS TO CLEAN THE SIGNAL “Deterministic method” Result Step by step correction of every oscillation by fit zoom

  46. FIRST ATTEMPTS TO CLEAN THE SIGNAL Correction Stage Methods: 2/2 “Spline method for D1 and D2 ” “Lower frequency” features are fitted by a spline function calculated for each Disturbance (red curve) Event appears as background noise in comparison with D1

  47. FIRST ATTEMPTS TO CLEAN THE SIGNAL “Spline method” Particular Higher frequencies are not fitted

  48. FIRST ATTEMPTS TO CLEAN THE SIGNAL “Spline method”An Event Event Event

  49. FIRST ATTEMPTS TO CLEAN THE SIGNAL “Spline method”An Event Big Disturbance Noise

  50. FIRST ATTEMPTS TO CLEAN THE SIGNAL “Spline method”An Event …part of D1 cannot be entirely removed this way

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