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  • IS37 Målselv
    Processing Example Explosion Database Regional Bulletin NUCLEAR TEST MONITORING INFRASOUND IS37 Målselv IS37 Infrasound station in Målselv The station is part of the International Monitoring System IMS with designated name I37NO The map to the right shows location of the new station as well as the operating seismic arrays PS27 and PS28 The station is now constructed and operating at the location Brannmoen in Målselv Norway The station consists of 10 measurement points each with one microbarometer of type MB2005 and a pipe array wind noise reduction system with dimension 18x18 meters A Central Facility building CRF is supplying all sites with electric power through buried copper cables Intra array communication is using fiber optic cables Each of the 10 sites will have single power and fiber cable to the CRF The fiber cables is installed in 40 mm pipes The lower right map shows the sites and the paths for the trenches required for the cables There are all together about 5200 meters of trenches and 9500 meters of cables both copper and fiber Each of the sites H0 H9 have an instrument vault plus a pipe array for wind noise suppression The site is surrounded by a 20x20

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2finfrasound%2fIS37%2f (2016-02-03)
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  • Current Installations - NORSAR
    the ARCES array Currently an experimental infrasound installation consisting of four sensors is installed at ARCES two sensors in the first ring located at ARA1 and ARA2 and two sensors in the second ring ARB2 and ARB3 Swedish network In addition to Apatity and ARCES NORSAR has access to the data from the Swedish Infrasound Network which has been in operation since the beginning of the 1970s Operated by the Swedish Institute of Space Physics the network has until recently comprised four infrasound stations Kiruna Jamton Lycksele and Uppsala The station in Uppsala was moved to Sodankyla Finland during the summer of 2006 The arrays in this network are triangular with a distance between sensors of only 75 meters The figure shows the current Nordic infrasound network along with two explosion sites Apatity Russia The Apatity seismic infrasonic array is one of the main infrasonic installations available in northern Europe The infrasonic component is a small aperture microbarographic array installed in conjunction with the seismic array near lake Imandra in the Kola Peninsula Data is digitized at the array site and transmitted in real time to a processing center in Apatity The figure shows the geometry of the combined Apatity

    Original URL path: http://www.norsar.no/monitoring/print/619/0/ (2016-02-03)
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  • Current Installations - NORSAR
    turned out to be quite sensitive to infrasound signals have been useful in our studies of infrasound waves The figure shows the geometry of the ARCES array Currently an experimental infrasound installation consisting of four sensors is installed at ARCES two sensors in the first ring located at ARA1 and ARA2 and two sensors in the second ring ARB2 and ARB3 Swedish network In addition to Apatity and ARCES NORSAR has access to the data from the Swedish Infrasound Network which has been in operation since the beginning of the 1970s Operated by the Swedish Institute of Space Physics the network has until recently comprised four infrasound stations Kiruna Jamton Lycksele and Uppsala The station in Uppsala was moved to Sodankyla Finland during the summer of 2006 The arrays in this network are triangular with a distance between sensors of only 75 meters The figure shows the current Nordic infrasound network along with two explosion sites Apatity Russia The Apatity seismic infrasonic array is one of the main infrasonic installations available in northern Europe The infrasonic component is a small aperture microbarographic array installed in conjunction with the seismic array near lake Imandra in the Kola Peninsula Data is digitized

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2finfrasound%2fOther-Installations%2f (2016-02-03)
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  • Processing Example - NORSAR
    two surface explosions Closer view of the Kiruna and Apatity data for the two surface explosions Click on image for larger version Although the Kiruna signals are clipped due to the limited dynamic range of the digitizer we have found that reliable azimuths can be easily estimated using either f k analysis or a cross correlation technique bottom left The fact that the array is very small 75 meters across

    Original URL path: http://www.norsar.no/monitoring/print/620/0/ (2016-02-03)
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  • Processing Example - NORSAR
    IS37 Målselv Other Installations Processing Example Explosion Database Regional Bulletin NUCLEAR TEST MONITORING INFRASOUND Processing Example Processing Example To illustrate the processing of infrasonic signals from stations in the Nordic network we show data for two of the stations Kiruna Sweden and Apatity Russia for two surface explosions in NW Russia near the Norwegian border These explosions were presumably conducted for the purpose of destroying old ammunition We record a number of such events each year from this site Kiruna data for two surface explosions Apatity data for two surface explosions Closer view of the Kiruna and Apatity data for the two surface explosions Click on image for larger version Although the Kiruna signals are clipped due to the limited dynamic range of the digitizer we have found that reliable azimuths can be easily estimated using either f k analysis or a cross correlation technique bottom left The fact that the array is very small 75 meters across does not seem to be a disadvantage at the frequencies of interest for this type of events 2 8 Hz For the Apatity array the dynamic range is much larger and the true signal can therefore be recorded The cross correlation analysis

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2finfrasound%2fProcessing-Example%2f (2016-02-03)
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  • Explosion Database - NORSAR
    approximately 175 km The top left panel shows waveforms on the central seismometer the seismic P phase A seismic Sphase B and an infrasonic arrival approximately 640 seconds after the estimated origin time C The broadband f k analysis plots right side indicate that all of these signals come from a backazimuth of about 173 degrees The bottom left panel shows P S and infrasonic array beams steered towards the epicenter and illustrates the gain in signal to noise ratio resulting from the beamforming process Click on image for larger version Time aligned signals The figure shows time aligned signals on the ARA0 sz sensor of the ARCES array for all the explosions at the northern Finland site which took place in the year 2002 The epicentral distance is 175 km A large amplitude acoustic signal approximately 600 seconds following the origin time is observed for almost all of these events but unlike the seismic signals which are almost identical for each explosion the temporal nature and amplitudes of the acoustic signals differ greatly from event to event Click on image for larger version Infrasound detection statistics The figure displays a color scaled indication of an infrasound detection statistic for

    Original URL path: http://www.norsar.no/monitoring/print/621/0/ (2016-02-03)
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  • Explosion Database - NORSAR
    Explosion site on the map below These explosions which are carried out annually in August September are presumably for the purpose of destroying old ammunition and generate unusually strong infrasonic signals in addition to seismic signals Typical seismic and infrasonic signals generated by these explosions The figure shows waveform data from the ARCES seismic array one minute prior to and 14 minutes after a surface explosion in northern Finland at a distance of approximately 175 km The top left panel shows waveforms on the central seismometer the seismic P phase A seismic Sphase B and an infrasonic arrival approximately 640 seconds after the estimated origin time C The broadband f k analysis plots right side indicate that all of these signals come from a backazimuth of about 173 degrees The bottom left panel shows P S and infrasonic array beams steered towards the epicenter and illustrates the gain in signal to noise ratio resulting from the beamforming process Click on image for larger version Time aligned signals The figure shows time aligned signals on the ARA0 sz sensor of the ARCES array for all the explosions at the northern Finland site which took place in the year 2002 The epicentral distance is 175 km A large amplitude acoustic signal approximately 600 seconds following the origin time is observed for almost all of these events but unlike the seismic signals which are almost identical for each explosion the temporal nature and amplitudes of the acoustic signals differ greatly from event to event Click on image for larger version Infrasound detection statistics The figure displays a color scaled indication of an infrasound detection statistic for the ARCES and Apatity arrays for a five minutes long time window following each event in the database of explosions at the northern Finland site during the

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2finfrasound%2fExplosion-Database%2f (2016-02-03)
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  • Regional Bulletin - NORSAR
    for which either the ARCES seismic array or the Apatity infrasound array observed infrasound signals The blue triangles show the GBF event locations and the red stars show the location of known sites with explosions either at the Earth s surface or in the atmosphere Note that the automatic GBF locations usually scatter over a larger area around these source regions Also note that the GBF locations employ a fixed

    Original URL path: http://www.norsar.no/monitoring/print/622/0/ (2016-02-03)
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