Data Analysis and Results

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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

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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)

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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

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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 PROCESSING1 1Constantin Ionescu and Daniela Ghica

1National Institute for Earth Physics, 12 Calugareni St., PO Box MG-2, 077125 Magurele, Romania, Tel.: +4021 405 60 65, e-mail: daniela@infp.ro CTBT: Science and Technology 2011

T3 - P17

EElleemmeenntt LLaattiittuuddee

((ooNN))

LLoonnggiittuuddee ((ooEE))

AAllttiittuuddee ((mm))

DDeepptthh ((mm))

SSeennssoorr ttyyppee

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

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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)

- in teract ive rev iew 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

590569

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329346

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May-10 Jun-10 Jul-10 Aug-10 Sep-10 Oct-10 Nov-10 Dec-10 Jan-11 Feb-11 Mar-11 Apr-11

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Figure 3 - Yearly azimuthal distribution of the IPLOR infrasound detections

Back-azimuth (deg) Ev. No.

Date Origin time Arrival time Latitude

(oN) Longitude

(oE) 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

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June 20100

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August 20100

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December 2010

Figure 5

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May 2010 - April 2011

Figure 4

Figure 6 Detected infrasound signals reviewed and displayed with GPMCC