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  • Special Events - NORSAR
    completed comprise more than 300 monitoring stations Six of these stations among them some of the largest and most advance ones are situated on Norwegian territory and are operated by NORSAR The North Korean nuclear test on 9 October 2006 was the first and until now the only nuclear explosion that has taken place after the CTBT organization in Vienna began regular processing of signals from a global monitoring network The figure shows the recordings from one of NORSAR s seismic monitoring stations the ARCES array near Karasjok northern Norway Oct 9th 2006 01 44 40 GMT ARCES is located at a distance of 6260 km from the explosion site and the seismic pressure waves were recorded at this station 9 minutes and 43 seconds after the explosion took place The North Korean nuclear explosion was detected and located immediately after it took place and the global monitoring system thus passed this unforeseen test From radionuclide measurements it became clear that the explosion was nuclear and not chemical The size of the explosion was relatively moderate with a Richter magnitude of 4 2 This corresponds to approximately one kiloton of TNT if the explosion was fully coupled and carried out

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2fdetseis%2fCapability-Assessment%2fSpecial-Events%2f (2016-02-03)
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  • Monitoring North Korea's Nuclear Test Site - NORSAR
    test site for possible future explosions Our analysis is based upon the so called Site Specific Threshold Monitoring SSTM approach Using actual seismic data recorded by a given network SSTM calculates a continuous threshold trace which provides at any instance in time an upper magnitude bound on any seismic event that could have occurred at the target site at that time The above figure shows the operational IMS network for the North Korean test site on Oct 9th 2006 day 282 The network selected for this study comprises in general those IMS stations which had the best signal to noise ratio SNR for the 9 October explosion plus the Chinese station at Mudanjiang MDJ about 370 km north of the test site We also included the South Korean array KSRS which recorded the nuclear explosion but was not operational in the IDC at the time The figure to the right shows registrations from the KRSC array from 2007 282 01 35 30 and illustrates the procedure for tuning of the KSRS array for site specific monitoring of the North Korean test site All of the stations were tuned in a similar way The upper trace shows the short term average

    Original URL path: http://www.norsar.no/monitoring/print/633/0/ (2016-02-03)
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  • Monitoring North Korea's Nuclear Test Site - NORSAR
    North Korea conducted an underground nuclear explosion at a test site near Kimchaek The explosion was detected by several seismic stations in the International Monitoring System IMS and was also reported by the United States Geological Survey USGS The event magnitude was reported as 4 1 by the International Data Center IDC in Vienna Austria and 4 2 by the USGS NORSAR analyzed the recorded waveforms at selected seismic stations in order to investigate the capability of the global seismic network to monitor the North Korean test site for possible future explosions Our analysis is based upon the so called Site Specific Threshold Monitoring SSTM approach Using actual seismic data recorded by a given network SSTM calculates a continuous threshold trace which provides at any instance in time an upper magnitude bound on any seismic event that could have occurred at the target site at that time The above figure shows the operational IMS network for the North Korean test site on Oct 9th 2006 day 282 The network selected for this study comprises in general those IMS stations which had the best signal to noise ratio SNR for the 9 October explosion plus the Chinese station at Mudanjiang MDJ about 370 km north of the test site We also included the South Korean array KSRS which recorded the nuclear explosion but was not operational in the IDC at the time The figure to the right shows registrations from the KRSC array from 2007 282 01 35 30 and illustrates the procedure for tuning of the KSRS array for site specific monitoring of the North Korean test site All of the stations were tuned in a similar way The upper trace shows the short term average STA of the optimally filtered 3 8 Hz P beam steered towards the epicenter

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2fdetseis%2fCapability-Assessment%2fMonitoring-North-Koreas-Nuclear-Test-Site%2f (2016-02-03)
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  • The Capability to Monitor North Korea's Nuclear Test Site - NORSAR
    traditional analysis tools in detecting locating and characterizing the source of the disturbance Thus the threshold monitoring method is a supplement to and not a replacement of traditional method The figure to the right shows monitoring results from the operational IMS network for the North Korean test site for the day of the nuclear test 9 October 2006 In this figure we have used only those of our selected stations that were operational at the IDC during that day i e without KSRS The continuous detection threshold traces for three station P wave detection red are close to magnitude 4 0 or slightly below except for occasional increases during the nuclear test at 01 35 and during some interfering events later in the day The monitoring thresholds blue average about magnitude 3 0 The individual station P thresholds black are also shown The figure shows a one day plot of detection traces red and monitoring traces blue for 15 November 2006 when a large earthquake occurred in the Kurile Islands The top panel uses the IMS network including KSRS and the middle panel shows the effect of adding the MDJ station We find that the current IMS primary network supplemented

    Original URL path: http://www.norsar.no/monitoring/print/634/0/ (2016-02-03)
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  • The Capability to Monitor North Korea's Nuclear Test Site - NORSAR
    attention to any time instance when a given threshold is exceeded This will enable the analyst to focus efforts on those events that are truly of interest in a monitoring situation The analyst will then apply other traditional analysis tools in detecting locating and characterizing the source of the disturbance Thus the threshold monitoring method is a supplement to and not a replacement of traditional method The figure to the right shows monitoring results from the operational IMS network for the North Korean test site for the day of the nuclear test 9 October 2006 In this figure we have used only those of our selected stations that were operational at the IDC during that day i e without KSRS The continuous detection threshold traces for three station P wave detection red are close to magnitude 4 0 or slightly below except for occasional increases during the nuclear test at 01 35 and during some interfering events later in the day The monitoring thresholds blue average about magnitude 3 0 The individual station P thresholds black are also shown The figure shows a one day plot of detection traces red and monitoring traces blue for 15 November 2006 when a

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2fdetseis%2fCapability-Assessment%2fThe-Capability-to-Monitor-North-Koreas-Nuclear-Test-Site%2f (2016-02-03)
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  • Infrasound - NORSAR
    Norway is located in the European Arctic region This station will probably be installed in 2012 Another infrasound station IS18 on Greenland is in operation but is located too far away to give any significant contribution to the regional monitoring of low magnitude events in the European Arctic An important area of research at NORSAR is to develop methods for joint seismic infrasonic analysis of events recorded at regional distances

    Original URL path: http://www.norsar.no/monitoring/print/618/0/ (2016-02-03)
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  • Infrasound - NORSAR
    infrasonic arrays distributed globally As can be observed from the map only one of the stations in this network IS37 in Bardufoss northern Norway is located in the European Arctic region This station will probably be installed in 2012 Another infrasound station IS18 on Greenland is in operation but is located too far away to give any significant contribution to the regional monitoring of low magnitude events in the European

    Original URL path: http://www.norsar.no/Contents.aspx?PageUrl=monitoring%2finfrasound%2f (2016-02-03)
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  • 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

    Original URL path: http://www.norsar.no/monitoring/print/727/0/ (2016-02-03)
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