Data Analysis and Results ! ! ! ! ! ! ! Recently deployed in the Vrancea epicentral area by National Institute for Earth Physics 2.5 km aperture (figure 1) 7 seismic sites (PLOR): PLOR1, PLOR2, PLOR3, PLOR4, PLOR5, PLOR6, PLOR7 7 infrasound elements (IPLOR): IPL2, IPL3, IPL4, IPH4, IPH5, IPH6, IPH7 Sites 2, 3 and 4 are additionally equipped with electrometers and 3C fluxgate sensors Collected data are continuously recorded and real-time transmitted to the Romanian National Data Centre (Bucharest) Main applications: (1) acoustic measurement, consisting of detection of the infrasound events (explosions, mine and quarry blasts, earthquakes, aircraft etc.) (2) seismic monitoring of the local and regional events Plostina Seismo - Acoustic Array Figure1 - Plostina seismo-acoustic array configuration ! ! Cansi, Y. (1995), An Automatic Seismic Event Processing for Detection and Location; the P.M.C.C. Method, Geophysical Research Letters, 22, 9, 1021-1024 Wessel P., Smith W .H .F. (1995). New version of the Generic Mapping Tool released. EOS Trans. AGU, p 329 (see also URL: gmt.soest.hawaii.edu) ! ! The data processing in this study was performed with a program kindly provided and supported Maps were created using GMT software (Wessel & Smith 1995) based on the Progressive Multi-Channel Correlation (PMCC) algorithm; this program was by the CTBTO PTS Summary References Acknowledgments ! ! ! ! ! ! ! ! Applying the PMCC algorithm, infrasonic waves can be detected as generated over a large effective source area surrounding the epicenter. The PMCC algorithm allows a precise description of the global wave train with complex variations of azimuth and velocity, based on the ability to obtain high-resolution continuous detection and propagation parameter measurements The infrasound data recorded with the IPLOR array are automatic processed using a program based on the Progressive Multi-Channel Correlation (PMCC) algorithm A standard detector DFX (Detection and Features eXtraction) used by the International Data Centre (IDC) is applied for the IPLOR data The results obtained by applying the typical detector for acoustic signals are presented Seasonal variation in the IPLOR detection back-azimuth are observed due to the winds fields during the year High-resolution continuous detection and propagation parameter measurements, i.e. accurate description of the wave train with complex variations of azimuth and velocity, are obtained from IPLOR data using PMCC algorithm ROMANIAN INFRASOUND STRUCTURE: DESIGN AND DATA PROCESSING 1 1 Constantin Ionescu and Daniela Ghica 1 National Institute for Earth Physics, 12 Calugareni St., PO Box MG-2, 077125 Magurele, Romania, Tel.: +4021 405 60 65, e-mail: [email protected] CTBT: Science and Technology 2011 T3 - P17 Element Latitude ( o N) Longitude ( o E) Altitude (m) Depth (m) Sensor type PLOR1 45.852 26.6466 648 3 BB-CGM40T Strong motion ES-T triaxial magnetometer MAG-03MS PLOR2 IPL2 45.850 26.644 647 3 BB-CGM40T Strong motion ES-T triaxial magnetometer MAG-03MS microbarometer PLOR3 IPL3 45.854 26.646 665 3 BB-CGM40T Strong motion ES-T triaxial magnetometer MAG-03MS microbarometer MBAZEL2007 PLOR4 IPL4 IPH4 45.851 26.650 616 3, 30, 50 SP-GS21, BB-STS2 Strong motion ES-T triaxial magnetometer MAG-03MS microbarometer Chaparal MBAZEL2007 PLOR5 IPH5 45.842 26.642 586 3 BB-CGM40T Strong motion ES-T microbarometer Chaparal PLOR6 IPH6 45.846 26.664 687 3 BB-CGM40T Strong motion ES-T microbarometer Chaparal PLOR7 IPH7 45.860 26.641 831 3 BB-CGM40T Strong motion ES-T microbarometer Chaparal Infrasound Infrastructure IPH4 IPH5 IPH6 IPH7 ! ! ! ! ! ! ! ! The infrasound data recorded with IPLOR during one year (1 May 2010 - 30 April 2011) were processed with a software kindly provided by CTBTO PTS, and based on the Progressive Multi-Channel Correlation (PMCC) algorithm (Cansi, 1995): - automatic infrasound detector DFX-PMCC for signal detection and characterization (back-azimuth, horizontal trace velocity, frequency content, amplitude duration) - interactive review of the data/results with GPMCC (part of Geotool software g r a p h i c a l interface) IPLOR infrasound detections were associated with a list compiled from the Reviewed Event Bulletins of CTBT International Data Centre, and Upper Silesian Coal Basin Bulletin 2010 and Lubin Copper Basin Bulletin 2010 The investigation of the IPLOR infrasound detections observed during the year shows (figure 4) strong seasonal variations of the back-azimuth: - during the summer prevails eastern directions in the observed events (see figure 5) - during the winter-spring, a large number of events coming mainly from the N-V direction are detected (see figure 5) This behavior seems to be in accordance with the ECMWF global atmospheric model on the winds fields during the year: seasonal changing in the wind direction is reflected in the yearly station performance 8 acoustic events (explosions) observed at IPLOR were selected in order to exemplify the variation of the detection capability of the acoustic array during the year (table 1 ) Results of the detected infrasound signals reviewed with GPMCC for these 8 events are depicted in figure 6 Monthly statistics of the IPLOR infrasound detections is plotted in figure 2 Yearly azimuthal distribution of the IPLOR infrasound detections is represented in figure 3 Figure 3 - Detected infrasound signals reviewed and displayed with GPMCC Figure 2 - Monthly statistics of the IPLOR infrasound detections 590 569 448 599 258 364 329 346 524 270 278 98 0 100 200 300 400 500 600 May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Dec-10 Jan-11 Feb-11 Mar-11 Apr-11 No. of detections 0 45 90 135 180 225 270 315 0 60 120 180 240 300 360 Day Figure 3 - Yearly azimuthal distribution of the IPLOR infrasound detections Back-azimuth (deg) Ev. No. Date Origin time Arrival time Latitude ( o N) Longitude ( o E) expected observed Horizontal trace velocity (km/s) Cfreq (Hz) 1 10/06/2010 12:59:28 14:03:10 51.218 40.746 55.03 38.96 0.345 0.98 2 13/06/2010 03:58:05 04:30:00 48.045 33.4078 62.20 60.92 0.355 0.80 3 18/06/2010 08:00:14 08:52:50 52.870 35.800 37.02 36.67 0.339 1.04 4 20/08/2010 15:14:33 16:09:50 45.404 38.418 88.89 83.38 0.344 1.40 5 03/10/2010 15:43:42 16:32:30 51.438 16.194 312.71 293.97 0.328 2.49 6 05/10/2010 12:49:16 13:23:50 50.362 18.921 313.89 288.83 0.327 1.54 7 16/12/2010 10:35:51 11:21:40 50.059 18.422 310.28 298.42 0.322 1.64 8 21/12/2010 15:29:28 15:58:40 50.073 19.168 312.76 302.09 0.331 2.04 Table 1 - Examples of IPLOR detected arrivals 0 45 90 135 180 225 270 315 0.3 0.4 speed (km/s) June 2010 0 45 90 135 180 225 270 315 0.3 0.4 speed (km/s) August 2010 0 45 90 135 180 225 270 315 0.3 0.4 speed (km/s) October 2010 0 45 90 135 180 225 270 315 0.3 0.4 speed (km/s) December 2010 Figure 5 0 45 90 135 180 225 270 315 0.3 0.4 speed (km/s) May 2010 - April 2011 Figure 4 Figure 6 Detected infrasound signals reviewed and displayed with GPMCC