The CTBTO/WMO Atmospheric Backtracking Response System and the Data Fusion Exercise 2007

DTIC Science & Technology

2008-09-01

sensitivity of the measurement (sample) towards releases at all points on the globe . For a more comprehensive description, see the presentation from last...localization information, including the error ellipse, is comparatively small. The red spots on the right image mark seismic events that occurred on...hours indicated in the calendar of the PTS post-processing software WEB- GRAPE . 2008 Monitoring Research Review: Ground-Based Nuclear

The Comprehensive Nuclear Test Ban Treaty (Counterproliferation Papers, Future Warfare Series, Number 54)

DTIC Science & Technology

2010-06-01

parts to detect a nuclear explosion: seismic, hydroacoustic, infrasound and radionuclide. Figure 3. CTBTO International Monitoring System Sites26...Conference,” (Oct. 14, 2009), www.armscontrol.org.. [17] from earthquakes and mining explosions, but have proved effective in detecting past nuclear...hydroacoustic monitoring stations detect sound waves in the oceans, and the 60 infrasound stations detect above ground, ultra-low frequency sound waves

Influence of atmospheric transport patterns on xenon detections at the CTBTO radionuclide network

NASA Astrophysics Data System (ADS)

Krysta, Monika; Kusmierczyk-Michulec, Jolanta

2016-04-01

In order to fulfil its task of monitoring for signals emanating from nuclear explosions, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) operates global International Monitoring System (IMS) comprising seismic, infrasound, hydroacoustic and radionuclide measurement networks. At present, 24 among 80 radionuclide stations foreseen by the Comprehensive Nuclear-Test-Ban Treaty (CTBT) are equipped with certified noble gas measurement systems. Over a past couple of years these systems collected a rich set of measurements of radioactive isotopes of xenon. Atmospheric transport modelling simulations are crucial to an assessment of the origin of xenon detected at the IMS stations. Numerous studies undertaken in the past enabled linking these detections to non Treaty-relevant activities and identifying main contributors. Presence and quantity of xenon isotopes at the stations is hence a result of an interplay of emission patterns and atmospheric circulation. In this presentation we analyse the presence or absence of radioactive xenon at selected stations from an angle of such an interplay. We attempt to classify the stations according to similarity of detection patterns, examine seasonality in those patterns and link them to large scale or local meteorological phenomena. The studies are undertaken using crude hypotheses on emission patterns from known sources and atmospheric transport modelling simulations prepared with the FLEXPART model.

Maintenance and Logistics Support for the International Monitoring System Network of the CTBTO

NASA Astrophysics Data System (ADS)

Haslinger, F.; Brely, N.; Akrawy, M.

2007-05-01

The global network of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), once completed, will consist of 321 monitoring facilities of four different technologies: hydroacoustic, seismic, infrasonic, and radionuclide. As of today, about 65% of the installations are completed and contribute data to the products issued by the International Data Centre (IDC) of the CTBTO. In order to accomplish the task to reliably collect evidence for any potential nuclear test explosion anywhere on the planet, all stations are required to perform to very high data availability requirements (at least 98% data availability over a 12-month period). To enable reaching this requirement, a three-layer concept has been developed to allow efficient support of the IMS stations: Operations, Maintenance and Logistics, and Engineering. Within this concept Maintenance and Logistics provide second level support of the stations, whereby problems arising at the station are assigned through the IMS ticket system to Maintenance if they cannot be resolved on the Operations level. Maintenance will then activate the required resources to appropriately address and ultimately resolve the problem. These resources may be equipment support contracts, other third party contracts, or the dispatch of a maintenance team. Engineering Support will be activated if the problem requires redesign of the station or after catastrophic failures when a total rebuild of a station may be necessary. In this model, Logistics Support is responsible for parts replenishment and support contract management. Logistics Support also collects and analyzes relevant failure mode and effect information, develops supportability models, and has the responsibility for document management, obsolescence, risk & quality, and configuration management, which are key elements for efficient station support. Maintenance Support in addition is responsible for maintenance strategies, for planning and oversight of the execution of preventive maintenance programs by the Station Operators, and for review of operational troubleshooting procedures used in first level support. Particular challenges for the efficient and successful Maintenance and Logistics Support of the IMS network lie in the specific political boundary conditions regulating its implementation, in the fact that all IMS facilities and their equipment are owned by the respective host countries, and in finding the appropriate balance between outsourcing services and retaining essential in-house expertise.

Blind Source Separation of Seismic Events with Independent Component Analysis: CTBT related exercise

NASA Astrophysics Data System (ADS)

Rozhkov, Mikhail; Kitov, Ivan

2015-04-01

Blind Source Separation (BSS) methods used in signal recovery applications are attractive for they use minimal a priori information about the signals they are dealing with. Homomorphic deconvolution and cepstrum estimation are probably the only methods used in certain extent in CTBT applications that can be attributed to the given branch of technology. However Expert Technical Analysis (ETA) conducted in CTBTO to improve the estimated values for the standard signal and event parameters according to the Protocol to the CTBT may face problems which cannot be resolved with certified CTBTO applications and may demand specific techniques not presently used. The problem to be considered within the ETA framework is the unambiguous separation of signals with close arrival times. Here, we examine two scenarios of interest: (1) separation of two almost co-located explosions conducted within fractions of seconds, and (2) extraction of explosion signals merged with wavetrains from strong earthquake. The importance of resolving the problem related to case 1 is connected with the correct explosion yield estimation. Case 2 is a well-known scenario of conducting clandestine nuclear tests. While the first case can be approached somehow with the means of cepstral methods, the second case can hardly be resolved with the conventional methods implemented at the International Data Centre, especially if the signals have close slowness and azimuth. Independent Component Analysis (in its FastICA implementation) implying non-Gaussianity of the underlying processes signal's mixture is a blind source separation method that we apply to resolve the mentioned above problems. We have tested this technique with synthetic waveforms, seismic data from DPRK explosions and mining blasts conducted within East-European platform as well as with signals from strong teleseismic events (Sumatra, April 2012 Mw=8.6, and Tohoku, March 2011 Mw=9.0 earthquakes). The data was recorded by seismic arrays of the International Monitoring System of CTBTO and by small-aperture seismic array Mikhnevo (MHVAR) operated by the Institute of Geosphere Dynamics, Russian Academy of Sciences. Our approach demonstrated a good ability of separation of seismic sources with very close origin times and locations (hundreds of meters), and/or having close arrival times (fractions of seconds), and recovering their waveforms from the mixture. Perspectives and limitations of the method are discussed.

Improvement of IDC/CTBTO Event Locations in Latin America and the Caribbean Using a Regional Seismic Travel Time Model

NASA Astrophysics Data System (ADS)

Given, J. W.; Guendel, F.

2013-05-01

The International Data Centre is a vital element of the Comprehensive Test Ban Treaty (CTBT) verification mechanism. The fundamental mission of the International Data Centre (IDC) is to collect, process, and analyze monitoring data and to present results as event bulletins to Member States. For the IDC and in particular for waveform technologies, a key measure of the quality of its products is the accuracy by which every detected event is located. Accurate event location is crucial for purposes of an On Site Inspection (OSI), which would confirm the conduct of a nuclear test. Thus it is important for the IDC monitoring and data analysis to adopt new processing algorithms that improve the accuracy of event location. Among them the development of new algorithms to compute regional seismic travel times through 3-dimensional models have greatly increased IDC's location precision, the reduction of computational time, allowing forward and inverse modeling of large data sets. One of these algorithms has been the Regional Seismic Travel Time model (RSTT) of Myers et al., (2011). The RSTT model is nominally a global model; however, it currently covers only North America and Eurasia in sufficient detail. It is the intention CTBTO's Provisional Technical Secretariat and the IDC to extend the RSTT model to other regions of the earth, e.g. Latin America-Caribbean, Africa and Asia. This is particularly important for the IDC location procedure, as there are regions of the earth for which crustal models are not well constrained. For this purpose IDC has launched a RSTT initiative. In May 2012, a technical meeting was held in Vienna under the auspices of the CTBTO. The purpose of this meeting was to invite National Data Centre experts as well as network operators from Africa, Europe, the Middle East, Asia, Australia, Latin and North America to discuss the context under which a project to extend the RSTT model would be implemented. A total of 41 participants from 32 Member States were present. The Latin America and Caribbean region with a rapidly expanding group of advanced seismic networks was selected as a pilot project for the implementation of a regional RSTT initiative. This poster will assess the actions taken by the IDC in order to advance the RSTT project in the Latin America and Caribbean Region.

Recent development of infrasound monitoring network in Romania

NASA Astrophysics Data System (ADS)

Ghica, Daniela; Popa, Mihaela; Ionescu, Constantin

2017-04-01

The second half of 2016 was marked at National Institute for Earth Physics (NIEP) by a significant development of infrasound monitoring infrastructure in Romania. In addition to IPLOR, the 6-element acoustic array installed at Plostina, in the central part of Romania, since 2009, two other four-element arrays were deployed. The first one, BURARI infrasound research array, was deployed in late July 2016, under a joint effort of AFTAC, USA and NIEP, in the northern part of Romania, in Bucovina region. The sites, placed in vicinity of the central elements of BURAR seismic array (over 1.2 km aperture), are equipped with Chaparral Physics Model 21 microbarometers and Reftek RT 130 data loggers. The data, used mainly for research purposes within the scientific collaboration project between NIEP and AFTAC, are available to scientific community. The second one is a PTS portable infrasound array (I67RO) deployed for one year, starting with the end of September 2016, within a collaboration project between NIEP and PTS of the Preparatory Commission for CTBTO. This array is located in the western part of Romania, at Marisel, Cluj County, covering a 0.9 km aperture and being equipped with CEA/DAM MB2005 microbarometers and Reftek RT 130 data loggers. This joint experiment aims to contribute both to advanced understanding of infrasound sources in Central-Europe and to ARISE design study project, as an expansion of the spatial coverage of the European infrasound network. The data recorded by the three infrasound arrays deployed in Romania, during a same time interval (October - December 2016) were processed into detection arrival bulletins applying CEA/DASE PMCC algorithm embedded in DTK-GPMCC (extended CTBTO NDC-in-a-box) and WinPMCC software applications. The results were plotted and analyzed using DTK-DIVA software (extended CTBTO NDC-in-a-box), in order to assess detectability of each station, as well as the capacity of fusing detections into support of infrasound monitoring activity at NIEP. We present infrasound signals generated by an impulsive event (accidental explosion of a train carrying liquid petroleum gas in Hitrino, Bulgaria) recorded on these three arrays. The features calculated for the arrivals detected (backazimuth, arrival time, frequency and celerity) are used to associate signals with event and observe individually array performance.

Remote Calibration Procedure and Results for the Ctbto AS109 STS-2HG at Ybh

NASA Astrophysics Data System (ADS)

Uhrhammer, R. A.; Taira, T.; Hellweg, M.

2013-12-01

Berkeley Digital Seismic Station (BDSN) YBH, located in Yreka, CA, USA, is certified as Auxiliary Seismic Station 109 (AS109) by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty organization (CTBTO). YBH, sited in an abandoned hard rock mining drift, houses a Streckeisen STS-2HG triaxial broadband seismometer (the AS109 sensor) and a co-sited three-component set of Streckeisen STS-1 broadband seismometers and a Kinemetrics Episensor strong motion accelerometer (the BDSN sensors). CTBTO requested that we preform a remote calibration test of the STS-2HG (20,000 V/(m/s) nominal sensitivity) to verify its response and sensitivity. The remote calibration test was done successfully on June 17, 2013 and we report here on the procedure and results of the calibration. The calibration of the STS-2HG (s/n 30235) was accomplished using two Random Telegraph (RT) stimuli which were applied to the triaxial U,V,W component calibration coils through an appropriate series resistance to limit the drive current. The first was a four hour RT at 1.25 Hz (to determine the low-frequency response) and the second was a one hour RT at 25 Hz (to determine the high-frequency response). The RT stimulus signals were generated by the Kinemetrics Q330 data logger and both the stimuli and the response were recorded simultaneously with synchronous sampling at 100 sps. The RT calibrations were invoked remotely from Berkeley. The response to the 1.25 Hz RT stimulus was used to determine the seismometer natural period, fraction of critical damping and sensitivity of the STS-2HG sensors and the response to the 25 Hz RT stimulus was used to determine their corresponding high-frequency response. The accuracy of the sensitivity as determined by the response to the RT stimuli is limited by the accuracy of the calibration coil motor constant (2 g/A) provided on the factory calibration sheet. As a check on the accuracy of the sensitivity determined from the response to the RT stimuli, we also compare the ground motions inferred from the STS-2HG with the corresponding ground motions inferred from the co-sited STS-1's and the Episensor strong motion accelerometer using seismic signals which have adequate signal-to-noise ratios in passband common to both instruments.

Completing and sustaining IMS network for the CTBT Verification Regime

NASA Astrophysics Data System (ADS)

Meral Ozel, N.

2015-12-01

The CTBT International Monitoring System is to be comprised of 337 facilities located all over the world for the purpose of detecting and locating nuclear test explosions. Major challenges remain, namely the completion of the network where most of the remaining stations have either environmental, logistical and/or political issues to surmont (89% of the stations have already been built) and the sustainment of a reliable and state-of the-art network covering 4 technologies - seismic, infrasound , hydroacoustic and radionuclide. To have a credible and trustworthy verification system ready for entry into force of the Treaty, the CTBTO is protecting and enhancing its investment of its global network of stations and is providing effective data to the International Data Centre (IDC) and Member States. Regarding the protection of the CTBTO's investment and enhanced sustainment of IMS station operations, the IMS Division is enhancing the capabilities of the monitoring system by applying advances in instrumentation and introducing new software applications that are fit for purpose. Some examples are the development of noble gas laboratory systems to process and analyse subsoil samples, development of a mobile noble gas system for onsite inspection purposes, optimization of Beta Gamma detectors for Xenon detection, assessing and improving the efficiency of wind noise reduction systems for infrasound stations, development and testing of infrasound stations with a self-calibrating capability, and research into the use of modular designs for the hydroacoustic network.

The Analysis of North Korea's Nuclear Tests by Turkish National Data Center

NASA Astrophysics Data System (ADS)

Semin, K.; Meral Ozel, N.; Destici, T. C.; Necmioglu, O.; Kocak, S.

2013-12-01

The Democratic People's Republic of Korea (DPRK) announced the conduct of a third underground nuclear test on 12 February 2013 in the northeastern part of the country as the previous tests that were conducted in 2009 and 2006. The latest nuclear test is the best detected nuclear event by the global seismic networks. The magnitude estimates show that each new test increased in size when compared with the previous one. As Turkish NDC (National Data Center), we have analyzed the 2013 and 2009 nuclear tests using seismic data from International Monitoring System (IMS) stations through the International Data Center (IDC) located in Vienna. Discrimination analysis was performed based on mb:Ms magnitude ratio and spectral analysis. We have also applied array based waveform cross-correlation to show the similarity of the nuclear tests and precise arrival time measurements for relative location estimates and basic infrasound analysis using two IMS infrasound stations for the 2013 event. Seismic analysis were performed using softwares such as Geotool, EP (Event processor from Norsar) and Seismic Analysis Code (SAC) and the infrasound data were analyzed by using PMCC from CEA-France. The IMS network is operating under the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). The CTBTO verification system is under continuous development, also making use of the state of the art technologies and methodologies.

The GEOSCOPE Program : state of the art in 2004

NASA Astrophysics Data System (ADS)

Roult, G.; Lepine, J.; Rivera, L.; Stutzmann, E.; Group, G.

2004-12-01

The GEOSCOPE program was launched in 1982 by the National Institute of Sciences of Universe (INSU), a department of the French National Center of Scientific Research (CNRS), at the instigation of the Institute of Physics of the Earth of Paris (IPGP). The purpose of the GEOSCOPE program was the installation of about 25 stations well distributed worldwide (in particular in the southern hemisphere), in the standard configuration defined by the FDSN (very broad-band 24 bit, continuous recording at 20sps). The GEOSCOPE program is operating 28 digital very-broadband stations. Data from large events are teletransmitted for some stations (by phone line or through internet) and made available within one day. A satellite transmission system is now working, in cooperation with the french military agency CEA/DASE, in cooperation with CTBTO (Dzumac in New Caledonia). An agreement between GEOSCOPE and CTBTO allows us to get data continuously and with a low gain. The next CTBTO stations to be installed are ATD (Djibouti) and MBO (Senegal) in 2005. In terms of siting locations, the aim of the GEOSCOPE program is almost fulfilled; we plan to install a new station in MARQ (Marquesas Islands), one in Russia at high latitude at VOR (Vorkouta), one in Patagonia (COY in Chile), in order to fill some geographical gaps in the southern hemisphere. We installed in 2004 a joint station with IRIS and the CTBTO at TRIS (Tristan Da Cunha), in the southern Atlantic ocean. DCC in Antarctica is a joint EOST-Strasbourg/Concordia-Italy station. Our goal is now to replace our old digitizers by Quanterra ones, and to transmit all data in near real-time. At present 4 stations are sending their data in quasi-real time (DZM, ECH, SSB, FDF and RER). An inversion method for the fundamental mode Rayleigh wave spectra has made possible the rapid determination of the mechanism and the seismic moments. This determination is done routinely for all events with Ms > 6.5 from the teletransmitted stations data. The estimate Power Spectral Density plots have been computed for each station and are available on the Web site. Some small to medium earthquakes are not detected and thus are not referenced in the earthquake catalogues. Most of these events are in the southern hemisphere where the lack of seismic stations creates a detection sensitivity gap. We estimate that more than a hundred southern hemisphere events per year with magnitude between 4.5 and 5.5 go undetected by the worldwide networks. We use a surface wave analysis method to effectively detect and locate these earthquakes, particularly near-ridge events. Most GEOSCOPE stations are equipped with STS1 seismometers, only a few ones with STS2 seismometers. We are planning to move some stations from the northern hemisphere to the southern one, inorder to fill a geographical instrumental gap. We are equipping all stations with seismometers but also with microthermometers, microbarometers, in order to clean the seismic signal and to study potential correlations between the seismic signal and these environmental parameters. Some of our stations have long seismic time series (SSB in France and TAM in Algeria). Removing the atmospheric pressure effect is absolutely necessary for scientists using low frequency free oscillation modes, helping studies on the 'hum'.

2017 Guralp Affinity Digitizer Evaluation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.

Sandia National Laboratories has tested and evaluated two Guralp Affinity digitizers. The Affinity digitizers are intended to record sensor output for seismic and infrasound monitoring applications. The purpose of this digitizer evaluation is to measure the performance characteristics in such areas as power consumption, input impedance, sensitivity, full scale, self- noise, dynamic range, system noise, response, passband, and timing. The Affinity digitizers are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO).

IMS Infrasound Monitoring Test Site at Trafelberg, Austria: Preliminary Results from In-Situ Response Measurements of Infrasound Elements

DTIC Science & Technology

2010-09-01

IMS INFRASOUND MONITORING TEST SITE AT TRAFELBERG, AUSTRIA: PRELIMINARY RESULTS FROM IN-SITU RESPONSE MEASUREMENTS OF INFRASOUND ELEMENTS Thomas...The International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) has a unique infrasound test site...all four infrasound elements at I99 were made from 0.008 Hz to several Hz. For all four elements, from 0.01 to 0.1 Hz, the measured magnitude and

Ambient Noise Analysis from Selected CTBTO (Comprehensive Test Ban Treaty Organization) Sites

DTIC Science & Technology

2015-02-11

AGENCY NAME(S) AND ADDRESS(ES) Robert H. Headrick Office of Naval Research 875 North Randolph Street Arlington, VA 22203-1995 10. SPONSOR/MONITOR’S...Canada HA03 Juan Fernandez Island Chile HA04 Crozet Islands France HA05 Guadeloupe France Co HA06 Socorro Island Mexico HA07 Flores Portugal...2), 61- 73 (1974). 8. W.J. Pierson, Jr ., and R.A. Stacy. NASA Report CR-2247, National Technical Information Service, Springfield, VA 22151 (1973

Hyperion 5113/A Infrasound Sensor Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion John

2015-09-01

Sandia National Laboratories has tested and evaluated an infrasound sensor, the 5113/A manufactured by Hyperion. These infrasound sensors measure pressure output by a methodology developed by the University of Mississippi. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, and dynamic range. The 5113/A infrasound sensor is a new revision of the 5000 series intended to meet the infrasound application requirements for use in the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).

Evaluation of Two Guralp Preamplifiers for GS13 Seismometer Application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.

Sandia National Laboratories has tested and evaluated a new preamplifier, the Guralp Preamplifier for GS13, manufactured by Guralp. These preamplifiers are used to interface between Guralp digitizers and Geotech GS13 Seismometers. The purpose of the preamplifier evaluation was to measure the performance characteristics in such areas as power consumption, input impedance, sensitivity, full scale, self-noise, dynamic range, system noise, response, passband, and timing. The Guralp GS13 Preamplifiers are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO).

Production of pure 133mXe for CTBTO

NASA Astrophysics Data System (ADS)

Peräjärvi, K.; Eronen, T.; Gorelov, D.; Hakala, J.; Jokinen, A.; Kettunen, H.; Kolhinen, V.; Laitinen, M.; Moore, I. D.; Penttilä, H.; Rissanen, J.; Saastamoinen, A.; Toivonen, H.; Turunen, J.; Äystö, J.

2014-01-01

Underground nuclear weapon detonations release gaseous species into the atmosphere. The most interesting isotopes/isomers from the detection point of view are 131mXe, 133mXe, 133Xe and 135Xe. We have developed a method that employs high-precision Penning trap mass spectrometry at the JYFLTRAP facility, the University of Jyväskylä, to produce pure calibration samples of these isotopes/isomers. Among developments this work required a new mass resolution record of a few parts-per-million. Here the status and future plans of the project are reviewed.

Re-establishment of the IMS Hydroacoustic Station HA04, Crozet Islands, France.

NASA Astrophysics Data System (ADS)

Haralabus, Georgios; Stanley, Jerry; Zampolli, Mario; Grenard, Patrick; Nielsen, Peter; Le Bras, Ronan; Brown, David; Bittner, Paulina; Wang, Haijun; Gore, Jane; Amir, Menachem; Bereza, Slava

2017-04-01

The incorporation of the hydroacoustic station HA04, Crozet Islands, France, into the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) is a 17 year saga that had a happy ending on 29 December 2016. On that day, following a major engineering and logistical undertaking, the station was successfully installed. While still in its initial testing phase, HA04 sends continuously quality data at the International Data Centre (IDC), pending official certification and promotion to mainstream operational status. Similarly to most other cabled hydroacoustic stations in the IMS, HA04 is comprised of two triplets of moored hydrophones deployed on both sides of Possession Island (Crozet Islands) sending uninterrupted data to a shore facility via submarine fiber optic cables. The designed frequency pass-band is 1 - 100 Hz. Data are relayed to Vienna via a shore based satellite link in real time. According to CTBTO's standard requirements, the design life of HA04 is at least 20 years, maintenance-free for the underwater system. An outline of the main phases of this project, highlights from the installation operations and examples of received hydroacoustic signals associated with recent underwater seismic activity in the Indian Ocean as well as vocalizations from marine mammals acquired by the new HA04 are presented here. HA04 is scheduled to be fully integrated into the operational platform of IDC in the next six months, which will enable registered researchers to access archived monitoring data and processing software, or via the National Data Centres (NDCs).

Real-time Stack Monitoring at the BaTek Medical Isotope Production Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

McIntyre, Justin I.; Agusbudiman, A.; Cameron, Ian M.

2016-04-01

Radioxenon emissions from radiopharmaceutical production are a major source of background concentrations affecting the radioxenon detection systems of the International Monitoring System (IMS). Collection of real-time emissions data from production facilities makes it possible to screen out some medical isotope signatures from the IMS radioxenon data sets. This paper describes an effort to obtain and analyze real-time stack emissions data with the design, construction and installation of a small stack monitoring system developed by a joint CTBTO-IDC, BATAN, and PNNL team at the BaTek medical isotope production facility near Jakarta, Indonesia.

The GEOSCOPE Program: state of the art in 2003 and perspectives

NASA Astrophysics Data System (ADS)

Roult, G.; Lepine, J.; Stutzmann, E.; Montagner, J.; Geoscope Group,.

2003-12-01

The GEOSCOPE program was launched in 1982 by the National Institute of Sciences of Universe (INSU), a department of the French National Center of Scientific Research (CNRS), at the instigation of the Institute of Physics of the Earth of Paris (IPGP). The purpose of the GEOSCOPE program was the installation of about 25 stations well distributed worldwide, in particular in the southern hemisphere, in the standard configuration defined by the FDSN (very broad-band 24 bit, continuous recording at 20sps). The GEOSCOPE program is operating 28 digital very-broadband stations. Data from large events are teletransmitted for some stations (by phone line or through internet) and made available within one day. A satellite transmission system is now working, in cooperation with the french military agency CEA/DASE, in cooperation with CTBTO (Dzumac in New Caledonia ). An agreement between GEOSCOPE and CTBTO allows us to get data continuously and with a low gain. The next CTBTO stations to be installed are ATD (Djibouti) and MBO (Senegal) in 2004. In terms of siting locations, the aim of the GEOSCOPE program is almost fulfilled; we plan to install a new station in MARQ (Marquesas Islands), one in Russia at high latitude at VOR (Vorkouta), one in Patagonia (COY in Chile), a joint station with IRIS at TRIS (Tristan Da Cunha) in order to fill some geographical gaps in the southern hemisphere. DCC in Antarctica is a joint EOST-Strasbourg/Concordia-Italy station. Our goal is now to replace our old digitizers by Quanterra ones, and to transmit all data in near real-time. An inversion method for the fundamental mode Rayleigh wave spectra has made possible the rapid determination of the mechanism and the seismic moments.This determination is done routinely for all events with Ms>6.8 from the teletransmitted stations data. The estimate Power Spectral Density plots have been computed for each station and are available on the Web site. Some small to medium earthquakes are not detected and thus are not referenced in the earthquake catalogues. Most of these eve nts are in the southern hemisphere where the lack of seismic stations creates a detection sensitivity gap. We estimate that more than a hundred southern hemisphere events per year with magnitude between 4.5 and 5.5 go undetected by the worldwide networks. We use a surface wave analysis method to effectively detect and locate these earthquakes, particular ly near-ridge events. Most GEOSCOPE stations are equipped with STS1 seismometers, only a few ones with STS2 seismometers. We are planning to move some stations from the northern hemisphere to the southern one. We are equipping all stations with thermometers, and also with microbarometers in order to clean routinely the signal from the atmospheric pressure effect.

Argon Collection And Purification For Proliferation Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Achey, R.; Hunter, D.

2015-10-09

In order to determine whether a seismic event was a declared/undeclared underground nuclear weapon test, environmental samples must be taken and analyzed for signatures that are unique to a nuclear explosion. These signatures are either particles or gases. Particle samples are routinely taken and analyzed under the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) verification regime as well as by individual countries. Gas samples are analyzed for signature gases, especially radioactive xenon. Underground nuclear tests also produce radioactive argon, but that signature is not well monitored. A radioactive argon signature, along with other signatures, can more conclusively determine whether an event wasmore » a nuclear test. This project has developed capabilities for collecting and purifying argon samples for ultra-low-background proportional counting. SRNL has developed a continuous gas enrichment system that produces an output stream containing 97% argon from whole air using adsorbent separation technology (the flow diagram for the system is shown in the figure). The vacuum swing adsorption (VSA) enrichment system is easily scalable to produce ten liters or more of 97% argon within twelve hours. A gas chromatographic separation using a column of modified hydrogen mordenite molecular sieve has been developed that can further purify the sample to better than 99% purity after separation from the helium carrier gas. The combination of these concentration and purification systems has the capability of being used for a field-deployable system for collecting argon samples suitable for ultra-low-background proportional counting for detecting nuclear detonations under the On-Site Inspection program of the CTBTO verification regime. The technology also has applications for the bulk argon separation from air for industrial purposes such as the semi-conductor industry.« less

Application of Radioxenon Stack Emission Data in High-Resolution Atmospheric Transport Modelling

NASA Astrophysics Data System (ADS)

Kusmierczyk-Michulec, J.; Schoeppner, M.; Kalinowski, M.; Bourgouin, P.; Kushida, N.; Barè, J.

2017-12-01

The Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) has developed the capability to run high-resolution atmospheric transport modelling by employing WRF and Flexpart-WRF. This new capability is applied to simulate the impact of stack emission data on simulated concentrations and how the availability of such data improves the overall accuracy of atmospheric transport modelling. The presented case study focuses on xenon-133 emissions from IRE, a medical isotope production facility in Belgium, and air concentrations detected at DEX33, a monitoring station close to Freiburg, Germany. The CTBTO is currently monitoring the atmospheric concentration of xenon-133 at 25 stations and will further expand the monitoring efforts to 40 stations worldwide. The incentive is the ability to detect xenon-133 that has been produced and released from a nuclear explosion. A successful detection can be used to prove the nuclear nature of an explosion and even support localization efforts. However, xenon-133 is also released from nuclear power plants and to a larger degree from medical isotope production facilities. The availability of stack emission data in combination with atmospheric transport modelling can greatly facilitate the understanding of xenon-133 concentrations detected at monitoring stations to distinguish between xenon-133 that has been emitted from a nuclear explosion and from civilian sources. Newly available stack emission data is used with a high-resolution version of the Flexpart atmospheric transport model, namely Flexpart-WRF, to assess the impact of the emissions on the detected concentrations and the advantage gained from the availability of such stack emission data. The results are analyzed with regard to spatial and time resolution of the high-resolution model and in comparison to conventional atmospheric transport models with and without stack emission data.

Bayesian Inference for Signal-Based Seismic Monitoring

NASA Astrophysics Data System (ADS)

Moore, D.

2015-12-01

Traditional seismic monitoring systems rely on discrete detections produced by station processing software, discarding significant information present in the original recorded signal. SIG-VISA (Signal-based Vertically Integrated Seismic Analysis) is a system for global seismic monitoring through Bayesian inference on seismic signals. By modeling signals directly, our forward model is able to incorporate a rich representation of the physics underlying the signal generation process, including source mechanisms, wave propagation, and station response. This allows inference in the model to recover the qualitative behavior of recent geophysical methods including waveform matching and double-differencing, all as part of a unified Bayesian monitoring system that simultaneously detects and locates events from a global network of stations. We demonstrate recent progress in scaling up SIG-VISA to efficiently process the data stream of global signals recorded by the International Monitoring System (IMS), including comparisons against existing processing methods that show increased sensitivity from our signal-based model and in particular the ability to locate events (including aftershock sequences that can tax analyst processing) precisely from waveform correlation effects. We also provide a Bayesian analysis of an alleged low-magnitude event near the DPRK test site in May 2010 [1] [2], investigating whether such an event could plausibly be detected through automated processing in a signal-based monitoring system. [1] Zhang, Miao and Wen, Lianxing. "Seismological Evidence for a Low-Yield Nuclear Test on 12 May 2010 in North Korea". Seismological Research Letters, January/February 2015. [2] Richards, Paul. "A Seismic Event in North Korea on 12 May 2010". CTBTO SnT 2015 oral presentation, video at https://video-archive.ctbto.org/index.php/kmc/preview/partner_id/103/uiconf_id/4421629/entry_id/0_ymmtpps0/delivery/http

The National Data Center Preparedness Exercise 2009 - First Results

NASA Astrophysics Data System (ADS)

Gestermann, Nicolai; Bönnemann, Christian; Ceranna, Lars; Wotawa, Gerhard

2010-05-01

The NDC preparedness initiative was initiated by 8 signature states. It has now a history of more than 2 years with two successful exercises and subsequent fruitful discussions during the NDC Evaluation Workshops of the CTBTO. The first exercise was carried out in 2007 (NPE07). The objectives of and the idea behind this exercise have been described in the working paper CTBT/WGB-28/DE-IT/1 of the CTBTO. The exercise simulates a fictitious violation of the CTBT and all NDCs are invited to clarify the nature of the selected event. This exercise should help to evaluate the effectiveness of analysis procedures applied at NDCs, as well as the quality, completeness, and usefulness of IDC products. Moreover, the NPE is a measure for the readiness of the NDCs to fulfil their duties in regard of the CTBT verification: the treaty compliance based judgments about the nature of events as natural or artificial and chemical or nuclear, respectively. The NPE09 has started on 1 October 2009, 00:00 UTC. In addition to the previous exercises, three technologies (seismology, infrasound, and radionuclide) have been taken into account leading to tentative mock events generated by strong explosions in open pit mines. Consequently, the first event, which fulfils all previously defined criteria, was close to the Kara-Zhyra mine in Eastern Kazakhstan and occurred on 28 November 2009 at 07:20:31 UTC. It generated seismic signals as well as infrasound signals at the closest IMS stations. The forward atmospheric transport modelling indicated that a sufficient number of radionuclide stations were also affected to enable the application of a negative testing scenario. First results of the seismo-acoustic analysis of the NPE09 event were presented along with details on the event selection process.

Radionuclide observables during the Integrated Field Exercise of the Comprehensive Nuclear-Test-Ban Treaty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burnett, Jonathan L.; Miley, Harry S.; Milbrath, Brian D.

In 2014 the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) undertook the Integrated Field Exercise (IFE) in Jordan. The exercise consisted of a simulated 0.5 – 2 kT underground explosion triggering an On-site Inspection (OSI) to search for evidence of a Treaty violation. This research evaluates two of the OSI techniques, including laboratory-based gamma-spectrometry of soil samples and in situ gamma-spectrometry for 17 particulate radionuclides indicative of nuclear weapon tests. The detection sensitivity is evaluated using real IFE and model data. It indicates that higher sensitivity laboratory measurements are the optimum technique during the IFE and OSI timeframes.

MB3a Infrasound Sensor Evaluation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.; McDowell, Kyle D.

2014-11-01

Sandia National Laboratories has tested and evaluated a new infrasound sensor, the MB3a, manufactured by Seismo Wave. These infrasound sensors measure pressure output by a methodology developed by researchers at the French Alternative Energies and Atomic Energy Commission (CEA) and the technology was recently licensed to Seismo Wave for production and sales. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, dynamic range, seismic sensitivity, and self- calibration ability. The MB3a infrasound sensors are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO).

Acoustic-Seismic Coupling in Porous Ground - Measurements and Analysis for On-Site-Inspection Support

NASA Astrophysics Data System (ADS)

Liebsch, Mattes; Gorschlüter, Felix; Altmann, Jürgen

2014-05-01

During on-site inspections (OSI) of the Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO) a local seismic network can be installed to measure seismic aftershock signals of an assumed underground nuclear explosion. These signals are caused by relaxation processes in and near the cavity created by the explosion and when detected can lead to a localisation of the cavity. This localisation is necessary to take gas samples from the ground which are analysed for radioactive noble gas isotopes to confirm or dismiss the suspicion of a nuclear test. The aftershock signals are of very low magnitude so they can be masked by different sources, in particular periodic disturbances caused by vehicles and aircraft in the inspection area. Vehicles and aircraft (mainly helicopters) will be used for the inspection activities themselves, e.g. for overhead imagery or magnetic-anomaly sensing. While vehicles in contact with the ground can excite soil vibrations directly, aircraft and vehicles alike emit acoustic waves which excite soil vibrations when hitting the ground. These disturbing signals are of periodic nature while the seismic aftershock signals are pulse-shaped, so their separation is possible. The understanding of the coupling of acoustic waves to the ground is yet incomplete, a better understanding is necessary to improve the performance of an OSI, e.g. to address potential consequences for the sensor placement, the helicopter trajectories etc. In a project funded by the Young Scientist Research Award of the CTBTO to one of us (ML), we investigated the acoustic-seismic coupling of airborne signals of jet aircraft and artificially induced ones by a speaker. During a measurement campaign several acoustic and seismic sensors were placed below the take-off trajectory of an airport at 4 km distance. Therefore taking off and landing jet aircraft passed nearly straightly above the setup. Microphones were placed close to the ground to record the sound pressure of incident acoustic signals and geophones were buried in different depths to measure the soil velocity. Additionally, a wooden box coated with acoustic damping foam was placed over some acoustic and seismic sensors to reduce the power of incident acoustic signals and thus the locally created seismic vibrations (under the box). The reduced soil velocity measured by geophones under the box corresponds mainly to vibrations created by acoustic-seismic coupling outside the box which travel through the soil and reach the sensor. Under certain conditions of frequency and incident angle of acoustic signals an increased seismic response was observed. This might indicate the excitation of seismic surface waves and is of special interest for the evaluation. The project aims to deliver a better understanding of the interaction of acoustic waves with the ground when hitting the surface. Recommendations for sensitive seismic measurements during CTBTO on-site inspections will be developed to reduce disturbing vibrations caused by airborne sources.

Inverse modeling of April 2013 radioxenon detections

NASA Astrophysics Data System (ADS)

Hofman, Radek; Seibert, Petra; Philipp, Anne

2014-05-01

Significant concentrations of radioactive xenon isotopes (radioxenon) were detected by the International Monitoring System (IMS) for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in April 2013 in Japan. Particularly, three detections of Xe-133 made between 2013-04-07 18:00 UTC and 2013-04-09 06:00 UTC at the station JPX38 are quite notable with respect to the measurement history of the station. Our goal is to analyze the data and perform inverse modeling under different assumptions. This work is useful with respect to nuclear test monitoring as well as for the analysis of and response to nuclear emergencies. Two main scenarios will be pursued: (i) Source location is assumed to be known (DPRK test site). (ii) Source location is considered unknown. We attempt to estimate the source strength and the source strength along with its plausible location compatible with the data in scenario (i) and (ii), respectively. We are considering also the possibility of a vertically distributed source. Calculations of source-receptor sensitivity (SRS) fields and the subsequent inversion are aimed at going beyond routine calculations performed by the CTBTO. For SRS calculations, we employ the Lagrangian particle dispersion model FLEXPART with high resolution ECMWF meteorological data (grid cell sizes of 0.5, 0.25 and ca. 0.125 deg). This is important in situations where receptors or sources are located in complex terrain which is the case of the likely source of detections-the DPRK test site. SRS will be calculated with convection enabled in FLEXPART which will also increase model accuracy. In the variational inversion procedure attention will be paid not only to all significant detections and their uncertainties but also to non-detections which can have a large impact on inversion quality. We try to develop and implement an objective algorithm for inclusion of relevant data where samples from temporal and spatial vicinity of significant detections are added in an iterative manner and the inversion is recalculated in each iteration. This procedure should gradually narrow down the set of hypotheses on the source term, where the source term is here understood as an emission in both spatial and temporal domains. Especially in scenario (ii) we expect a strong impact of non-detections for the reduction of possible solutions. For these and also other purposes like statistical quantification of typical background values, measurements from all IMS noble gas stations north of 30 deg S for a period from January to June 2013 were extracted from vDEC platform. We would like to acknowledge the Preparatory Commission for the CTBTO for kindly providing limited access to the IMS data. This work contains only opinions of the authors, which can not in any case establish legal engagement of the Provisional Technical Secretariat of the CTBTO. This work is partially financed through the project "PREPARE: Innovative integrated tools and platforms for radiological emergency preparedness and post-accident response in Europe" (FP7, Grant 323287).

Tipping point analysis of a large ocean ambient sound record

NASA Astrophysics Data System (ADS)

Livina, Valerie N.; Harris, Peter; Brower, Albert; Wang, Lian; Sotirakopoulos, Kostas; Robinson, Stephen

2017-04-01

We study a long (2003-2015) high-resolution (250Hz) sound pressure record provided by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) from the hydro-acoustic station Cape Leeuwin (Australia). We transform the hydrophone waveforms into five bands of 10-min-average sound pressure levels (including the third-octave band) and apply tipping point analysis techniques [1-3]. We report the results of the analysis of fluctuations and trends in the data and discuss the BigData challenges in processing this record, including handling data segments of large size and possible HPC solutions. References: [1] Livina et al, GRL 2007, [2] Livina et al, Climate of the Past 2010, [3] Livina et al, Chaos 2015.

IDC Re-Engineering Phase 2 System Specification Document Version 1.5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Satpathi, Meara Allena; Burns, John F.; Harris, James M.

This document contains the system specifications derived to satisfy the system requirements found in the IDC System Requirements Document for the IDC Re-Engineering Phase 2 project. This System Specification Document (SSD) defines waveform data processing requirements for the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). The routine processing includes characterization of events with the objective of screening out events considered to be consistent with natural phenomena or non-nuclear, man-made phenomena. This document does not address requirements concerning acquisition, processing and analysis of radionuclide data but does include requirements for the dissemination of radionuclide datamore » and products.« less

A portable infrasound generator.

PubMed

Park, Joseph; Robertson, James

2009-04-01

The rotary subwoofer is a novel low frequency transducer capable of efficiently generating infrasound from a compact source. A field-deployable version of this device may find application as a calibration source for infrasound arrays of the International Monitoring System (IMS) [(2001). The Global Verification Regime and the International Monitoring System (CTBTO Preparatory Commission Vienna International Centre, Vienna, Austria)]. A prototype tested at the IMS infrasound array I59US demonstrated the ability to insonify all elements of the array from a standoff distance of 3.8 km. Signal-to-noise ratios of continuous wave signals ranged from 5 to 15 dB, indicating the utility of this source to transmit controllable infrasound signals over distances of 5 km.

Overview of the 2009 and 2011 Sayarim Infrasound Calibration Experiments

NASA Astrophysics Data System (ADS)

Fee, D.; Waxler, R.; Drob, D.; Gitterman, Y.; Given, J.

2012-04-01

The establishment of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has stimulated infrasound research and development. However, as the network comes closer to completion there exists a lack of large, well-constrained sources to test the network and its capabilities. Also, significant uncertainties exist in long-range acoustic propagation due to a dynamic, difficult to characterize atmosphere, particularly the thermosphere. In 2009 and 2011 three large scale infrasound calibration experiments were performed in Europe, the Middle East, Africa, and Asia. The goal of the calibration experiments were to test the IMS infrasound network and validate atmospheric and propagation models with large, well-constrained infrasound sources. This presentation provides an overview of the calibration experiments, including deployment, atmospheric conditions during the experiments, explosion characterization, infrasonic signal detection and identification, and a discussion of the results and implications. Each calibration experiment consisted of singular surface detonation of explosives with nominal weights of 82, 10.24, and 102.08 tons on 26 August 2009, 24 January 2011, and 26 January 2011, respectively. These explosions were designed and conducted by the Geophysical Institute of Israel at Sayarim Military Range, Israel and produced significant infrasound detected by numerous permanent and temporary infrasound arrays in the region. The 2009 experiment was performed in the summer to take advantage of the westerly stratospheric winds. Infrasonic arrivals were detected by both IMS and temporary arrays deployed to the north and west of the source, including clear stratospheric arrivals and thermospheric arrivals with low celerities. The 2011 experiment was performed during the winter, when strong easterly stratospheric winds dominated in addition to a strong tropospheric jet (the jet stream). These wind jets allowed detection out to 6500 km, in addition to multiple tropospheric, stratospheric, and thermospheric arrivals at arrays deployed to the east. These experiments represented a considerable, successful collaboration between the CTBTO and numerous other groups and will provide a rich ground-truth dataset for detailed infrasound studies in the future.

Analysis of recordings from underwater controlled sources in the Pacific Ocean received by the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO)

NASA Astrophysics Data System (ADS)

Yamada, Tomoaki; Zampolli, Mario; Haralabus, Georgios; Heaney, Kevin; Prior, Mark; Isse, Takeshi

2016-04-01

Controlled impulsive scientific underwater sound sources in the Northwestern Pacific were observed at two IMS hydroacoustic stations in the Pacific Ocean. Although these experiments were conducted with the aim of studying the physical properties of the plate boundaries inside the Earth, they are also suitable for the investigation of long range underwater acoustic detections. In spite of the fact that the energy of these controlled impulsive scientific sources is significantly smaller than that of nuclear explosions, the signals were obtained by IMS hydrophone stations thousands of kilometres away and also by distant ocean bottom instruments operated by various Institutes, such as the Earthquake Research Institute, University of Tokyo. These experiments provide calibrated (yield, time, location) long-range acoustic transmissions, which enable one to examine the physics of long-range acoustic propagation and to verify the capabilities of the CTBTO IMS network to detect even small explosions.The two IMS stations used are H03 (Juan Fernandez Island, Chile) off the coast of Chile in the Southeastern Pacific and H11 (Wake Island, USA) in the Western Pacific. Both stations consist of two triplets of hydrophones in the SOFAR channel, which monitor the oceans for signs of nuclear explosions. H03 detected low-yield explosions above flat terrain at distances of 15,000 km across the Pacific as well as explosions above the landward slope off the coast of Japan at distances above 16,000 km across the Pacific. These records showed that source signatures, such as short duration and bubble pulses, were preserved over the long propagation distances. It was found that the observed maximum amplitudes from each source exhibit order of magnitude variations even when the yield and detonation depth are the same. The experimental data and transmission loss simulations suggest that bathymetric features around the sources and between the sources and the receivers are the main causes for these variations.

Influence of atmospheric convection on the long and short-range transport of Xe133 emissions.

NASA Astrophysics Data System (ADS)

Kusmierczyk-Michulec, Jolanta; Krysta, Monika; Gheddou, Abdelhakim; Nikkinen, Mika

2014-05-01

The International Monitoring System (IMS) developed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is a global system of monitoring stations, using four complementary technologies: seismic, hydroacoustic, infrasound and radionuclide. Data from all stations, belonging to IMS, are collected and transmitted to the International Data Centre (IDC) in Vienna, Austria. The radionuclide network comprises 79 stations, of which more than 60 are certified. The aim of radionuclide stations is a global monitoring of radioactive aerosols and radioactive noble gases supported by the atmospheric transport modelling (ATM). The ATM system is based on the Lagrangian Particle Dispersion Model, FLEXPART, designed for calculating the long-range and mesoscale dispersion of air pollution from point sources. In the operational configuration only the transport of the passive tracer is simulated. The question arises whether including other atmospheric processes, like convection, will improve results. To answer this question a series of forward simulations was conducted, assuming the maximum transport of 14 days. Each time 2 runs were performed: one with convection and one without convection. The release point was at the ANSTO facility in Australia. Due to the fact that CTBTO has recently received a noble gas emission inventory from the ANSTO facility we had a chance to do more accurate simulations. Studies have been performed to link Xe133 emissions with detections at the IMS stations supported by the ATM. The geographical localization to some extend justifies the assumption that the only source of Xe133 observed at the neighbouring stations, e.g. AUX04, AUX09 and NZX46, comes from the ANSTO facility. In simulations the analysed wind data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) were used with the spatial resolution of 0.5 degree. The results of quantitative and qualitative comparison will be presented.

IDC Re-Engineering Phase 2 System Requirements Document Version 1.4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, James M.; Burns, John F.; Satpathi, Meara Allena

This System Requirements Document (SRD) defines waveform data processing requirements for the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). The IDC applies, on a routine basis, automatic processing methods and interactive analysis to raw International Monitoring System (IMS) data in order to produce, archive, and distribute standard IDC products on behalf of all States Parties. The routine processing includes characterization of events with the objective of screening out events considered to be consistent with natural phenomena or non-nuclear, man-made phenomena. This document does not address requirements concerning acquisition, processing and analysis of radionuclide data,more » but includes requirements for the dissemination of radionuclide data and products.« less

IDC Re-Engineering Phase 2 System Requirements Document V1.3.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, James M.; Burns, John F.; Satpathi, Meara Allena

2015-12-01

This System Requirements Document (SRD) defines waveform data processing requirements for the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). The IDC applies, on a routine basis, automatic processing methods and interactive analysis to raw International Monitoring System (IMS) data in order to produce, archive, and distribute standard IDC products on behalf of all States Parties. The routine processing includes characterization of events with the objective of screening out events considered to be consistent with natural phenomena or non-nuclear, man-made phenomena. This document does not address requirements concerning acquisition, processing and analysis of radionuclide datamore » but includes requirements for the dissemination of radionuclide data and products.« less

A new methodological approach for worldwide beryllium-7 time series analysis

NASA Astrophysics Data System (ADS)

Bianchi, Stefano; Longo, Alessandro; Plastino, Wolfango

2018-07-01

Time series analyses of cosmogenic radionuclide 7Be and 22Na atmospheric activity concentrations and meteorological data observed at twenty-five International Monitoring System (IMS) stations of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) have shown great variability in terms of noise structures, harmonic content, cross-correlation patterns and local Hurst exponent behaviour. Noise content and its structure has been extracted and characterised for the two radionuclides time series. It has been found that the yearly component, which is present in most of the time series, is not stationary, but has a percentage weight that varies with time. Analysis of atmospheric activity concentrations of 7Be, measured at IMS stations, has shown them to be influenced by distinct meteorological patterns, mainly by atmospheric pressure and temperature.

Preliminary Results from an Hydroacoustic Experiment in the Indian Ocean

NASA Astrophysics Data System (ADS)

Royer, J.; Dziak, R. P.; Delatre, M.; Brachet, C.; Haxel, J. H.; Matsumoto, H.; Goslin, J.; Brandon, V.; Bohnenstiehl, D. R.; Guinet, C.; Samaran, F.

2008-12-01

We report initial results from a 14-month hydroacoustic experiment in the Indian Ocean conducted by CNRS/University of Brest and NOAA/Oregon State University. The objective was to monitor the low-level seismic activity associated with the three contrasting spreading ridges and deforming zones in the Indian Ocean. Three autonomous hydrophones, moored in the SOFAR channel, were deployed in October 2006 and recovered early 2008 by R/V Marion Dufresne, in the Madagascar Basin, and northeast and southwest of Amsterdam Island, complementing the two permanent hydroacoustic stations of the Comprehensive nuclear-Test-Ban Treaty Organization (CTBTO) located near Diego Garcia Island and off Cape Leeuwin. Our temporary network detected more than 2000 events. Inside the array, we located 592 events (compared to 49 in the NEIC earthquake catalog) with location errors less than 5 km and time error less than 2s. The hydrophone array detected on average 5 to 40 times more events per month than land-based networks. First-order observations indicate that hydroacoustic seismicity along the Southeast Indian ridge (SEIR) occurs predominantly along the transform faults. The Southwest Indian Ridge exhibits some periodicity in earthquake activity between adjacent ridge segments. Two large tectonic/volcanic earthquake swarms are observed along the Central Indian Ridge (near the triple junction) in September and December 2007. Moreover, many off ridge-axis events are also observed both south and north of the SEIR axis. Improved localization using the CTBTO records will help refine these preliminary results and further investigate extended volcanic sequences along the SEIR east of 80°E and other events outside of the temporary array. The records also display numerous vocalizations of baleen whales in the 20-40Hz bandwidth. The calls are attributed to fin whales, Antarctic blue whales and pygmy blue whales of Madagascar and Australian type. Their vocal activity is found to be highly seasonal, occurring mainly from April to October with subspecies variations. This array thus provides a unique data set to improve our understanding of the seismic activity in this region and to establish the occurrence and migration pattern of critically endangered whale species.

Fifty Years of Seismic Monitoring in Davao,Philippines

NASA Astrophysics Data System (ADS)

McNamara, D. J.

2016-12-01

The Manila Observatory was a 150 years old as of 2015. Fiftry years ago it began a seismic monitoring station in the Island of Mindanao, outside the city of Davao, 7 deg. N and 121 deg. E. approxiamtely. This station was chosen not only for its position on the Ring of Fire but also for the fact the the dip angle of the earth's manetic field is zeo at that location. When the CTBT was established and the Republic of the Philippines (RP) a signatory, the Davao station by agreement with RP, began to send its seismic data to the CTBT database in Vienna. This has continued to the present day with support from CTBTO for updates in equipment and maintainence. We discuss if such a private+government model is the way forward for more comprehensive monitoring in the future.

Evaluation of Two Guralp Preamplifiers for GS21 Seismometer Application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.; Slad, George William

2015-08-01

Sandia National Laboratories has tested and evaluated two Guralp preamplifiers for use with a GS21 seismometer application. The two preamplifiers have a gain factor of 61.39. The purpose of the preamplifier evaluation was to determine a measured gain factor, transfer function, total harmonic distortion, self-noise, application passband, dynamic range, seismometer calibration pass-through, and to comment on any issues encountered during the evaluation. The test results included in this report were in response to static, tonal, and dynamic input signals. The Guralp GS21 preamplifiers are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treatymore » Organization (CTBTO). Test methodologies used were based on IEEE Standards 1057 for Digitizing Waveform Recorders and 1241 for Analog to Digital Converters« less

Radionuclide observables during the Integrated Field Exercise of the Comprehensive Nuclear-Test-Ban Treaty.

PubMed

Burnett, Jonathan L; Miley, Harry S; Milbrath, Brian D

2016-03-01

In 2014 the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) undertook an Integrated Field Exercise (IFE14) in Jordan. The exercise consisted of a simulated 0.5-2 kT underground nuclear explosion triggering an On-site Inspection (OSI) to search for evidence of a Treaty violation. This research paper evaluates two of the OSI techniques used during the IFE14, laboratory-based gamma-spectrometry of soil samples and in-situ gamma-spectrometry, both of which were implemented to search for 17 OSI relevant particulate radionuclides indicative of nuclear explosions. The detection sensitivity is evaluated using real IFE and model data. It indicates that higher sensitivity laboratory measurements are the optimum technique during the IFE and within the Treaty/Protocol-specified OSI timeframes. Copyright © 2016 Elsevier Ltd. All rights reserved.

The 2013 Russian fireball largest ever detected by CTBTO infrasound sensors

NASA Astrophysics Data System (ADS)

Le Pichon, Alexis; Ceranna, Lars; Pilger, Christoph; Mialle, Pierrick; Brown, David; Herry, Pascal; Brachet, Nicolas

2013-07-01

15 February 2013, a large Earth-impacting fireball disintegrated over the Ural Mountains. This extraordinary event is, together with the 1908 Tunguska fireball, among the most energetic events ever instrumentally recorded. It generated infrasound returns, after circling the globe, at distances up to ~85,000 km, and was detected at 20 infrasonic stations of the global International Monitoring System (IMS). For the first time since the establishment of the IMS infrasound network, multiple arrivals involving waves that traveled twice round the globe have been clearly identified. A preliminary estimate of the explosive energy using empirical period-yield scaling relations gives a value of 460 kt of TNT equivalent. In the context of the future verification of the Comprehensive Nuclear-Test-Ban Treaty, this event provides a prominent milestone for studying in detail infrasound propagation around the globe for almost 3 days as well as for calibrating the performance of the IMS network.

CEA SMAD 2016 Digitizer Evaluation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.

Sandia National Laboratories has tested and evaluated an updated SMAD digitizer, developed by the French Alternative Energies and Atomic Energy Commission (CEA). The SMAD digitizers are intended to record sensor output for seismic and infrasound monitoring applications. The purpose of this digitizer evaluation is to measure the performance characteristics in such areas as power consumption, input impedance, sensitivity, full scale, self-noise, dynamic range, system noise, response, passband, and timing. The SMAD digitizers have been updated since their last evaluation by Sandia to improve their performance when recording at a sample rate of 20 Hz for infrasound applications and 100 Hzmore » for hydro-acoustic seismic stations. This evaluation focuses primarily on the 20 Hz and 100 Hz sample rates. The SMAD digitizers are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test- Ban-Treaty Organization (CTBTO).« less

On-Site inspections as a tool for nuclear explosion monitoring in the framework of the Comprehensive Nuclear Test Ban Treaty

NASA Astrophysics Data System (ADS)

Arndt, R.; Gaya-Pique, L.; Labak, P.; Tanaka, J.

2009-04-01

On-site inspections (OSIs) constitute the final verification measure under the Comprehensive Nuclear-Test-Ban Treaty (CTBT). OSIs are launched to establish whether or not a nuclear explosion has been carried out, thus they are conducted to verify States' compliance with the Treaty. During such an inspection, facts are gathered within a limited investigation area of 1000 Km2 to identify possible violators of the Treaty. Time scale (referring both to the preparation of the inspection as well as to the conduct of an OSI itself) is one of the challenges that an inspection team has to face when conducting an OSI. Other challenges are the size of the team - which is limited to 40 inspectors - and political limitations imposed by the Treaty in the use of allowed techniques. The Integrated Field Exercise 2008 (IFE08) recently conducted in Kazakhstan was the first large-scale, as well as the most comprehensive, on site inspection exercise ever conducted by the Preparatory Commission of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The exercise took place in a deserted area south east of Kurchatov, within the former Soviet Union's Semipalatinsk nuclear test site. In this paper we will provide an overview of the technical activities conducted by the inspection team during IFE08 in order to collect evidence for a hypothetical nuclear explosion test. The techniques applied can be distributed in four different blocks: visual observation (to look for man-made changes in the geomorphology as well as anthropogenic features related to an underground nuclear explosion, UNE); passive seismic monitoring (to identify possible aftershocks created by the UNE); radionuclide measurements (to collect evidence for radionuclide isotopes related to a nuclear explosion); and finally geophysical surveys (to identify geophysical signatures related to an UNE in terms of changes in the geological strata, to the hydrogeological regime, and in terms of the shallow remains of the infrastructure deployed during the preparation and monitoring of the test). The data collected during IFE08, together with data from previous exercises, set the fundaments of a database of invaluable value to be used by CTBTO in the future for a better understanding of the phenomenology related to a nuclear explosion.

Enhanced global Radionuclide Source Attribution for the Nuclear-Test-Ban Verification by means of the Adjoint Ensemble Dispersion Modeling Technique applied at the IDC/CTBTO.

NASA Astrophysics Data System (ADS)

Becker, A.; Wotawa, G.; de Geer, L.

2006-05-01

The Provisional Technical Secretariat (PTS) of the CTBTO Preparatory Commission maintains and permanently updates a source-receptor matrix (SRM) describing the global monitoring capability of a highly sensitive 80 stations radionuclide (RN) network in order to verify states signatories' compliance of the comprehensive nuclear-test-ban treaty (CTBT). This is done by means of receptor-oriented Lagrangian particle dispersion modeling (LPDM) to help determine the region from which suspicious radionuclides may originate. In doing so the LPDM FLEXPART5.1 is integrated backward in time based on global analysis wind fields yielding global source-receptor sensitivity (SRS) fields stored in three-hour frequency and at 1º horizontal resolution. A database of these SRS fields substantially helps in improving the interpretation of the RN samples measurements and categorizations because it enables the testing of source-hypothesis's later on in a pure post-processing (SRM inversion) step being feasible on hardware with specifications comparable to currently sold PC's or Notebooks and at any place (decentralized), provided access to the SRS fields is warranted. Within the CTBT environment it is important to quickly achieve decision-makers confidence in the SRM based backtracking products issued by the PTS in the case of the occurrence of treaty relevant radionuclides. Therefore the PTS has set up a highly automated response system together with the Regional Specialized Meteorological Centers of the World Meteorological Organization in the field of dispersion modeling who committed themselves to provide the PTS with the same standard SRS fields as calculated by their systems for CTBT relevant cases. This system was twice utilized in 2005 in order to perform adjoint ensemble dispersion modeling (EDM) and demonstrated the potential of EDM based backtracking to improve the accuracy of the source location related to singular nuclear events thus serving the backward analogue to the findings of the ensemble dispersion modeling (EDM) technique No. 5 efforts performed by Galmarini et al, 2004 (Atmos. Env. 38, 4607-4617). As the scope of the adjoint EDM methodology is not limited to CTBT verification but can be applied to any kind of nuclear event monitoring and location it bears the potential to improve the design of manifold emergency response systems towards preparedness concepts as needed for mitigation of disasters (like Chernobyl) and pre-emptive estimation of pollution hazards.

A 3D Numerical Survey of Seismic Waves Inside and Around an Underground Cavity

NASA Astrophysics Data System (ADS)

Esterhazy, S.; Schneider, F. M.; Perugia, I.; Bokelmann, G.

2016-12-01

Motivated by the need to detect an underground cavity within the procedure of an On-Site-Inspection (OSI) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), which might be caused by a nuclear explo- sion/weapon testing, we present our findings of a numerical study on the elastic wave propagation inside and around such an underground cavity.The aim of the CTBTO is to ban all nuclear explosions of any size anywhere, by anyone. Therefore, it is essential to build a powerful strategy to efficiently investigate and detect critical signatures such as gas filled cavities, rubble zones and fracture networks below the surface. One method to investigate the geophysical properties of an under- ground cavity allowed by the Comprehensive Nuclear-test Ban Treaty is referred to as "resonance seismometry" - a resonance method that uses passive or active seismic techniques, relying on seismic cavity vibrations. This method is in fact not yet entirely determined by the Treaty and there are also only few experimental examples that have been suitably documented to build a proper scientific groundwork. This motivates to investigate this problem on a purely numerical level and to simulate these events based on recent advances in the mathematical understanding of the underlying physical phenomena.Our numerical study includes the full elastic wave field in three dimensions. We consider the effects from an in- coming plane wave as well as point source located in the surrounding of the cavity at the surface. While the former can be considered as passive source like a tele-seismic earthquake, the latter represents a man-made explosion or a viborseis as used for/in active seismic techniques. For our simulations in 3D we use the discontinuous Galerkin Spectral Element Code SPEED developed by MOX (The Laboratory for Modeling and Scientific Computing, Department of Mathematics) and DICA (Department of Civil and Environmental Engineering) at the Politecnico di Milano. The computations are carried out on the Vienna Scientific Cluster (VSC).The accurate numerical modeling can facilitate the development of proper analysis techniques to detect the remnants of an underground nuclear test, help to set a rigorous scientific base of OSI and contribute to bringing the Treaty into force.

Numerical study of wave propagation around an underground cavity: acoustic case

NASA Astrophysics Data System (ADS)

Esterhazy, Sofi; Perugia, Ilaria; Schöberl, Joachim; Bokelmann, Götz

2015-04-01

Motivated by the need to detect an underground cavity within the procedure of an On-Site-Inspection (OSI) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), which might be caused by a nuclear explosion/weapon testing, we aim to provide a basic numerical study of the wave propagation around and inside such an underground cavity. The aim of the CTBTO is to ban all nuclear explosions of any size anywhere, by anyone. Therefore, it is essential to build a powerful strategy to efficiently investigate and detect critical signatures such as gas filled cavities, rubble zones and fracture networks below the surface. One method to investigate the geophysical properties of an underground cavity allowed by the Comprehensive Nuclear-test Ban Treaty is referred to as 'resonance seismometry' - a resonance method that uses passive or active seismic techniques, relying on seismic cavity vibrations. This method is in fact not yet entirely determined by the Treaty and there are also only few experimental examples that have been suitably documented to build a proper scientific groundwork. This motivates to investigate this problem on a purely numerical level and to simulate these events based on recent advances in the mathematical understanding of the underlying physical phenomena. Here, we focus our numerical study on the propagation of P-waves in two dimensions. An extension to three dimensions as well as an inclusion of the full elastic wave field is planned in the following. For the numerical simulations of wave propagation we use a high order finite element discretization which has the significant advantage that it can be extended easily from simple toy designs to complex and irregularly shaped geometries without excessive effort. Our computations are done with the parallel Finite Element Library NGSOLVE ontop of the automatic 2D/3D tetrahedral mesh generator NETGEN (http://sourceforge.net/projects/ngsolve/). Using the basic mathematical understanding of the physical equations and the numerical algorithms it is possible for us to investigate the wave field over a large bandwidth of wave numbers. This means we can apply our calculations for a wide range of parameters, while keeping the numerical error explicitly under control. The accurate numerical modeling can facilitate the development of proper analysis techniques to detect the remnants of an underground nuclear test, help to set a rigorous scientific base of OSI and contribute to bringing the Treaty into force.

Analysis of Radionuclide Releases from the Fukushima Dai-Ichi Nuclear Power Plant Accident Part I

NASA Astrophysics Data System (ADS)

Le Petit, G.; Douysset, G.; Ducros, G.; Gross, P.; Achim, P.; Monfort, M.; Raymond, P.; Pontillon, Y.; Jutier, C.; Blanchard, X.; Taffary, T.; Moulin, C.

2014-03-01

Part I of this publication deals with the analysis of fission product releases consecutive to the Fukushima Dai-ichi accident. Reactor core damages are assessed relying on radionuclide detections performed by the CTBTO radionuclide network, especially at the particulate station located at Takasaki, 210 km away from the nuclear power plant. On the basis of a comparison between the reactor core inventory at the time of reactor shutdowns and the fission product activities measured in air at Takasaki, especially 95Nb and 103Ru, it was possible to show that the reactor cores were exposed to high temperature for a prolonged time. This diagnosis was confirmed by the presence of 113Sn in air at Takasaki. The 133Xe assessed release at the time of reactor shutdown (8 × 1018 Bq) turned out to be in the order of 80 % of the amount deduced from the reactor core inventories. This strongly suggests a broad meltdown of reactor cores.

Infrasonic Detection of a Large Bolide over South Sulawesi, Indonesia on October 8, 2009: Preliminary Results

NASA Technical Reports Server (NTRS)

Silber, E. A.; Brown, P. G.; Le Pinchon, A.

2011-01-01

In the morning hours of October 8, 2009, a bright object entered Earth's atmosphere over South Sulawesi, Indonesia. This bolide disintegrated above the ground, generating stratospheric infrasound returns that were detected by infrasonic stations of the global International Monitoring System (IMS) Network of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) at distances up to 17 500 km. Here we present instrumental recordings and preliminary results of this extraordinary event. Using the infrasonic period-yield relations, originally derived for atmospheric nuclear detonations, we find the most probable source energy for this bolide to be 70+/-20 kt TNT equivalent explosive yield. A unique aspect of this event is the fact that it was apparently detected by infrasound only. Global events of such magnitude are expected only once per decade and can be utilized to calibrate infrasonic location and propagation tools on a global scale, and to evaluate energy yield formula, and event timing.

Numerical Modelling of circulation and internal tides on the Crozet plateau in support of the IMS/CTBTO hydroacoustic installation HA04

NASA Astrophysics Data System (ADS)

Lyard, Florent Henri; Zampolli, Mario; Marsaleix, Patrick

2014-05-01

Hydrophone stations of the Comprehensive Nuclear-Test-Ban Organisation (CTBTO) International Monitoring System (IMS), with the exception of one in Australia, comprise two triplets of submerged moored hydrophones, one North and one South of the island from which the respective system is deployed. Triplet distances vary approximately between 50 - 100 km kilometres from the island, with each triplet connected to the receiving shore equipment by fibre-optic submarine data cables. Once deployed, the systems relay underwater acoustic waveforms in the band 1 - 100 Hz in real time to Vienna via a shore based satellite link. The design life of hydroacoustic stations is at least 20 years, without need for any maintenance of the underwater system. The re-establishment of hydrophone monitoring station HA04 at Crozet (French Southern and Antarctic Territories) in the South-Western Indian Ocean is currently being investigated. The highly dynamic ocean environment at Crozet is governed by strong winds and generally high sea states at the surface, local circulation emanating from the sub-Antarctic front (SAF) and the Agulhas return current (ARC), moderate surface tides and strong internal tides. Deploying the submarine cables and triplets in such an environment requires careful evaluation of all risks and in particular the minimization of the exposure of the deployed system to excessively strong currents. This issue has been addressed by two studies which are briefly introduced here. In the first study, a linear spectral model was used to study and characterize the barotropic tide-driven currents on the Crozet plateau in three spatial dimensions. The M2 semi-diurnal component was shown to dominate in the area, driving sizeable internal tides. The estimate was quantitatively and spatially refined in the second study, in which a time stepping model was used taking into account the local ocean climatology and stratification, as well as the interplay between the seasonally varying local circulation and the internal tides. The numerical result showed a counter-clockwise circulation around Ile de la Possession and Ile de l'Est (Crozet Islands), with a strong component in the South. Internal waves propagating downslope in the near-bottom layers can be particularly intense South of the two islands, while the regions to the North appear to be more calm. The results from the studies are compared to a set of limited current measurements acquired during a survey campaign in 1998.

Towards an Ontology-Based Approach to Support Monitoring the Data of the International Monitoring System (IMS)

NASA Astrophysics Data System (ADS)

Laban, Shaban; El-Desouky, Ali

2010-05-01

The heterogeneity of the distributed processing systems, monitored data and resources is an obvious challenge in monitoring the data of International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban Treaty organization (CTBTO). Processing engineers, analysts, operators and other interested parties seek for intelligent tools and software that hide the underlying complexity of the systems, allowing them to manage the operation and monitoring the systems at a higher level, focusing on what the expected behavior and results should be instead of how to specifically achieve it. Also, it is needed to share common understanding of the structure of organization information, data, and products among staff, software agents, and policy making organs. Additionally, introducing new monitoring object or system should not complicate the overall system and should be feasible. An ontologybased approach is presented in this paper aiming to support monitoring real-time data processing and supervising the various system resources, focusing on integrating and sharing same knowledge and status information of the system among different environments. The results of a prototype framework is presented and analyzed.

IMS radionuclide monitoring after the announced nuclear test of the DPRK on 3 September 2017

NASA Astrophysics Data System (ADS)

Kusmierczyk-Michulec, J.; Kalinowski, M.; Bourgouin, P.; Boxue, L.; Gheddou, A.; Klingberg, F.; Leppaenen, A. P.; Schoeppner, M.; Werzi, R.; Wang, J.

2017-12-01

The International Monitoring System (IMS) developed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is a global system of monitoring stations, using four complementary technologies: seismic, hydroacoustic, infrasound and radionuclide. The radionuclide network comprises 80 stations, out of which 40 are to be equipped with noble gas systems. The aim of radionuclide stations is a global monitoring of radioactive aerosols, radioactive noble gases and atmospheric transport modelling (ATM). To investigate the transport of radionuclide emissions, the Provisional Technical Secretariat (PTS) operates an Atmospheric Transport Modelling (ATM) system based on the Lagrangian Particle Dispersion Model FLEXPART. The air mass trajectory provides a "link" between a radionuclide release and a detection confirmed by radionuclide measurements. The aim of this study is to demonstrate the RN analysis and the application of ATM to investigate the episodes of elevated levels of radioxenon observed by IMS stations after the sixth nuclear test, announced by the Democratic People's Republic of Korea (DPRK) at the Punggye-ri Nuclear Test Site on 3 September 2017. A comparison to the previous tests will be presented.

CATS, continuous automated testing of seismological, hydroacoustic, and infrasound (SHI) processing software.

NASA Astrophysics Data System (ADS)

Brouwer, Albert; Brown, David; Tomuta, Elena

2017-04-01

To detect nuclear explosions, waveform data from over 240 SHI stations world-wide flows into the International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), located in Vienna, Austria. A complex pipeline of software applications processes this data in numerous ways to form event hypotheses. The software codebase comprises over 2 million lines of code, reflects decades of development, and is subject to frequent enhancement and revision. Since processing must run continuously and reliably, software changes are subjected to thorough testing before being put into production. To overcome the limitations and cost of manual testing, the Continuous Automated Testing System (CATS) has been created. CATS provides an isolated replica of the IDC processing environment, and is able to build and test different versions of the pipeline software directly from code repositories that are placed under strict configuration control. Test jobs are scheduled automatically when code repository commits are made. Regressions are reported. We present the CATS design choices and test methods. Particular attention is paid to how the system accommodates the individual testing of strongly interacting software components that lack test instrumentation.

Effects of charge design features on parameters of acoustic and seismic waves and cratering, for SMR chemical surface explosions

NASA Astrophysics Data System (ADS)

Gitterman, Y.

2012-04-01

A series of experimental on-surface shots was designed and conducted by the Geophysical Institute of Israel at Sayarim Military Range (SMR) in Negev desert, including two large calibration explosions: about 82 tons of strong IMI explosives in August 2009, and about 100 tons of ANFO explosives in January 2011. It was a collaborative effort between Israel, CTBTO, USA and several European countries, with the main goal to provide fully controlled ground truth (GT0) infrasound sources in different weather/wind conditions, for calibration of IMS infrasound stations in Europe, Middle East and Asia. Strong boosters and the upward charge detonation scheme were applied to provide a reduced energy release to the ground and an enlarged energy radiation to the atmosphere, producing enhanced infrasound signals, for better observation at far-regional stations. The following observations and results indicate on the required explosives energy partition for this charge design: 1) crater size and local seismic (duration) magnitudes were found smaller than expected for these large surface explosions; 2) small test shots of the same charge (1 ton) conducted at SMR with different detonation directions showed clearly lower seismic amplitudes/energy and smaller crater size for the upward detonation; 3) many infrasound stations at local and regional distances showed higher than expected peak amplitudes, even after application of a wind-correction procedure. For the large-scale explosions, high-pressure gauges were deployed at 100-600 m to record air-blast properties, evaluate the efficiency of the charge design and energy generation, and provide a reliable estimation of the charge yield. Empirical relations for air-blast parameters - peak pressure, impulse and the Secondary Shock (SS) time delay - depending on distance, were developed and analyzed. The parameters, scaled by the cubic root of estimated TNT equivalent charges, were found consistent for all analyzed explosions, except of SS time delays clearly separated for the shot of IMI explosives (characterized by much higher detonation velocity than ANFO). Additionally acoustic records at close distances from WSMR explosions Distant Image (2440 tons of ANFO) and Minor Uncle (2725 tons of ANFO) were used to extend the charge and distance range for the SS delay scaled relationship, that showed consistency with SMR ANFO shots. The developed specific charge design contributed to the success of this unique dual Sayarim explosion experiment, providing the strongest GT0 sources since the establishment of the IMS network, that demonstrated clearly the most favorable westward/ eastward infrasound propagation up to 3400/6250 km according to appropriate summer/winter weather pattern and stratospheric wind directions, respectively, and thus verified empirically common models of infrasound propagation in the atmosphere. The research was supported by the CTBTO, Vienna, and the Israel Ministry of Immigrant Absorption.

Proceedings of the 2009 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marv A; Aguilar - Chang, Julio; Anderson, Dale

These proceedings contain papers prepared for the Monitoring Research Review 2009: Ground -Based Nuclear Explosion Monitoring Technologies, held 21-23 September, 2009 in Tucson, Arizona,. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Test Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States’ capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well asmore » potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Proceedings of the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marv A; Aguilar-chang, Julio; Arrowsmith, Marie

These proceedings contain papers prepared for the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 23-25 September, 2008 in Portsmouth, Virginia. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States’ capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoringmore » agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Proceedings of the 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A; Patterson, Eileen F

These proceedings contain papers prepared for the Monitoring Research Review 2010: Ground-Based Nuclear Explosion Monitoring Technologies, held 21-23 September, 2010 in Orlando, Florida,. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, National Science Foundation (NSF), Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, asmore » well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Proceedings of the 2011 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A.; Patterson, Eileen F.; Sandoval, Marisa N.

These proceedings contain papers prepared for the Monitoring Research Review 2011: Ground-Based Nuclear Explosion Monitoring Technologies, held 13-15 September, 2011 in Tucson, Arizona. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Defense Threat Reduction Agency (DTRA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), National Science Foundation (NSF), and other invited sponsors. The scientific objectives of the research are to improve the United States' capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is tomore » provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Stakeholder engagement for promoting the Comprehensive Nuclear-Test-Ban Treaty (CTBT): Malaysia’s experience

NASA Astrophysics Data System (ADS)

Rashid, F. I. A.; Zolkaffly, M. Z.; Jamal, N.

2018-01-01

In order to keep abreast on issues related to CTBT in Malaysia, Malaysian Nuclear Agency (Nuklear Malaysia), as the CTBT National Authority in Malaysia, has collaborated with local partners to implement various stakeholder engagement programme. This paper aims at highlighting Malaysia’s approach in promoting CTBT through stakeholder engagement programme targeted at multilevel stakeholders, both national and international. Such programmes includes participation in the international forums, inter-agency meetings, awareness seminars, training courses, technical visits to IMS station, promoting civil and scientific application of International Monitoring System (IMS) data and International Data Centre (IDC) products using Virtual Data Exploitation Center (vDEC), inviting youth groups to participate in the CTBTO Youth Group, and publications of CTBT-related topics. This approach has successfully fortify Malaysia’s commitments at the international level, enhanced national awareness of global multilateral framework, increased stakeholders awareness and their roles related to CTBT, as well as building domestic capacity on CTBT matters. In conclusion, stakeholder engagement is crucial in promoting and enhancing stakeholders understanding on CTBT. Continuous engagement with relevant stakeholders will enable effective dissemination and smooth implementation of CTBT related matters that will eventually support global universalization of CTBT.

Fusion of waveform events and radionuclide detections with the help of atmospheric transport modelling

NASA Astrophysics Data System (ADS)

Krysta, Monika; Kushida, Noriyuki; Kotselko, Yuriy; Carter, Jerry

2016-04-01

Possibilities of associating information from four pillars constituting CTBT monitoring and verification regime, namely seismic, infrasound, hydracoustic and radionuclide networks, have been explored by the International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) for a long time. Based on a concept of overlying waveform events with the geographical regions constituting possible sources of the detected radionuclides, interactive and non-interactive tools were built in the past. Based on the same concept, a design of a prototype of a Fused Event Bulletin was proposed recently. One of the key design elements of the proposed approach is the ability to access fusion results from either the radionuclide or from the waveform technologies products, which are available on different time scales and through various different automatic and interactive products. To accommodate various time scales a dynamic product evolving while the results of the different technologies are being processed and compiled is envisioned. The product would be available through the Secure Web Portal (SWP). In this presentation we describe implementation of the data fusion functionality in the test framework of the SWP. In addition, we address possible refinements to the already implemented concepts.

NetMOD version 1.0 user's manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion John

2014-01-01

NetMOD (Network Monitoring for Optimal Detection) is a Java-based software package for conducting simulation of seismic networks. Specifically, NetMOD simulates the detection capabilities of seismic monitoring networks. Network simulations have long been used to study network resilience to station outages and to determine where additional stations are needed to reduce monitoring thresholds. NetMOD makes use of geophysical models to determine the source characteristics, signal attenuation along the path between the source and station, and the performance and noise properties of the station. These geophysical models are combined to simulate the relative amplitudes of signal and noise that are observed atmore » each of the stations. From these signal-to-noise ratios (SNR), the probability of detection can be computed given a detection threshold. This manual describes how to configure and operate NetMOD to perform seismic detection simulations. In addition, NetMOD is distributed with a simulation dataset for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) International Monitoring System (IMS) seismic network for the purpose of demonstrating NetMOD's capabilities and providing user training. The tutorial sections of this manual use this dataset when describing how to perform the steps involved when running a simulation.« less

Proceedings of the 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A.; Benson, Jody; Patterson, Eileen F.

These proceedings contain papers prepared for the 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 19-21 September, 2006 in Orlando, Florida. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoringmore » agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Proceedings of the 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A.; Benson, Jody; Patterson, Eileen F.

These proceedings contain papers prepared for the 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 25-27 September, 2007 in Denver, Colorado. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoringmore » agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Estimating unbiased magnitudes for the announced DPRK nuclear tests, 2006-2016

NASA Astrophysics Data System (ADS)

Peacock, Sheila; Bowers, David

2017-04-01

The seismic disturbances generated from the five (2006-2016) announced nuclear test explosions by the Democratic People's Republic of Korea (DPRK) are of moderate magnitude (body-wave magnitude mb 4-5) by global earthquake standards. An upward bias of network mean mb of low- to moderate-magnitude events is long established, and is caused by the censoring of readings from stations where the signal was below noise level at the time of the predicted arrival. This sampling bias can be overcome by maximum-likelihood methods using station thresholds at detecting (and non-detecting) stations. Bias in the mean mb can also be introduced by differences in the network of stations recording each explosion - this bias can reduced by using station corrections. We apply a maximum-likelihood (JML) inversion that jointly estimates station corrections and unbiased network mb for the five DPRK explosions recorded by the CTBTO International Monitoring Network (IMS) of seismic stations. The thresholds can either be directly measured from the noise preceding the observed signal, or determined by statistical analysis of bulletin amplitudes. The network mb of the first and smallest explosion is reduced significantly relative to the mean mb (to < 4.0 mb) by removal of the censoring bias.

Investigations of Periodic Disturbances on Seismic Aftershock Recordings

NASA Astrophysics Data System (ADS)

Liebsch, Mattes; Gorschlüter, Felix; Knoop, Jan-Frederik; Altmann, Jürgen

2013-04-01

The Comprehensive Nuclear Test-Ban Treaty Organisation (CTBTO) runs the International Monitoring System (IMS) to detect possible violations of the treaty. The seismic sensors of the IMS are set up to detect every underground explosion with a yield of 1 kT TNT equivalent or even better everywhere on the world. Under consideration of all IMS data the hypocentre of a large underground explosion is located within an area of about 1000 sq km. To verify if it was a violation of the Test-Ban Treaty the CTBTO (after CTBT entry into force) is allowed to carry out an on-site inspection (OSI) in the area of suspicion. During an OSI the hypocentre is to be located much more precisely; for this a local seismic aftershock monitoring system (SAMS) can be installed to detect small seismic events caused as a consequence of the explosion, such as relaxation of the rock around the cavity. However the magnitude of these aftershock signals is extremely weak. Other difficulties arise from other seismic signals in the inspection area, for example caused by vehicles of the inspectors, from coupling of airborne signals to the ground, or even by intended attempts to disturb the OSI. While the aftershock signals have a pulsed shape, man-made seismic signals (primarily created by engines) usually show periodic characteristics and thus are representable as a sum of sine functions and their harmonics. A mathematical expression for the Hann-windowed discrete Fourier transform of the underlying sine is used to characterise every such disturbance by the amplitude, frequency and phase. The contributions of these sines are computed and subtracted from the complex spectrum sequentially. Synthetic sines superposed to real signals, orders of magnitude stronger than the latter, can be removed successfully. Removal of periodic content from the signals of a helicopter overflight reduces the amplitude by a factor 3.3 when the frequencies are approximately constant. To reduce or prevent disturbing seismic signals created by coupling of acoustic waves to the ground in the first place a better understanding of the acoustic-seismic coupling is required. Several acoustic and seismic measurements of periodic signals (e.g. helicopters) and pulse-shaped signals (fire crackers, hammer blows) were analysed. The data were evaluated with respect to the distance between event and sensor, the elevation angle of the signal and the burying depth of the seismic sensors. From the correlation of acoustic and seismic spectral peaks the ratio of their spectral amplitudes can be calculated which gives the frequency dependent coupling coefficient. In the ongoing analysis the influence of constructive interference of surface waves, created by acoustic-seismic coupling at different positions in the vicinity of the sensor, is of special interest. Several recommendations for an OSI were developed with respect to sensor placement and flight trajectory of helicopters.

On the usability of frequency distributions and source attribution of Cs-137 detections encountered in the IMS radio-nuclide network for radionuclide event screening and climate change monitoring

NASA Astrophysics Data System (ADS)

Becker, A.; Wotawa, G.; Zähringer, M.

2009-04-01

Under the provisions of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), airborne radioactivity is measured by means of high purity Germanium gamma ray detectors deployed in a global monitoring network. Almost 60 of the scheduled 80 stations have been put in provisional operations by the end of 2008. Each station daily sends the 24 hour samples' spectroscopic data to the Vienna based Provisional Technical Secretariat (PTS) of the CTBT Organization (CTBTO) for review for treaty-relevant nuclides. Cs-137 is one of these relevant isotopes. Its typical minimum detectable concentration is in the order of a few Bq/m3. However, this isotope is also known to occur in atmospheric trace concentrations, due to known non CTBT relevant processes and sources related to, for example, the re-suspension of cesium from historic nuclear tests and/or the Chernobyl reactor disaster, temporarily enhanced by bio-mass burning (Wotawa et al. 2006). Properly attributed cesium detections can be used as a proxy to detect Aeolian dust events (Igarashi et al, 2001) that potentially carry cesium from all aforementioned sources but are also known to play an important role for the radiative forcing in the atmosphere (shadow effect), at the surface (albedo) and the carbon dioxide cycle when interacting with oceanic phytoplankton (Mikami and Shi, 2005). In this context this paper provides a systematic attribution of recent Cs-137 detections in the PTS monitoring network in order to Characterize those stations which are regularly affected by Cs-137 Provide input for procedures that distinguish CTBT relevant detection from other sources (event screening) Explore on the capability of certain stations to use their Cs-137 detections as a proxy to detect aeolian dust events and to flag the belonging filters to be relevant for further investigations in this field (-> EGU-2009 Session CL16/AS4.6/GM10.1: Aeolian dust: initiator, player, and recorder of environmental change). References Igarashi, Y., M. Aoyama, K. Hirose,M. Takashi and S. Yabuki, 2001: Is It Possible to Use 90Sr and 137Cs As Tracers for the Aeolian Dust Transport? Water, Air, & Soil Pollution 130, 349-354. Mikami, M. and G. Shi, 2005: Preliminary summary of aeolian dust experiment on climate impact -Japan-Sino joint project ADEC. Geophysical Research Abstracts, 7, 05985 Wotawa, G., L.-E. De Geer, A. Becker, R.D'Amours, M. Jean, R. Servranck and K. Ungar, 2006: Inter- and intra-continental transport of radioactive cesium released by boreal forest fires, Geophys. Res. Lett. 33, L12806, doi: 10.1029/2006GL026206 Disclaimer The views expressed in this publication are those of the author and do not necessarily reflect the views of the CTBTO Preparatory Commission.

Global Monitoring of the CTBT: Progress, Capabilities and Plans (Invited)

NASA Astrophysics Data System (ADS)

Zerbo, L.

2013-12-01

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), established in 1996, is tasked with building up the verification regime of the CTBT. The regime includes a global system for monitoring the earth, the oceans and the atmosphere for nuclear tests, and an on-site inspection (OSI) capability. More than 80% of the 337 facilities of the International Monitoring System (IMS) have been installed and are sending data to the International Data Centre (IDC) in Vienna, Austria for processing. These IMS data along with IDC processed and reviewed products are available to all States that have signed the Treaty. Concurrent with the build-up of the global monitoring networks, near-field geophysical methods are being developed and tested for OSIs. The monitoring system is currently operating in a provisional mode, as the Treaty has not yet entered into force. Progress in installing and operating the IMS and the IDC and in building up an OSI capability will be described. The capabilities of the monitoring networks have progressively improved as stations are added to the IMS and IDC processing techniques refined. Detection thresholds for seismic, hydroacoustic, infrasound and radionuclide events have been measured and in general are equal to or lower than the predictions used during the Treaty negotiations. The measurements have led to improved models and tools that allow more accurate predictions of future capabilities and network performance under any configuration. Unplanned tests of the monitoring network occurred when the DPRK announced nuclear tests in 2006, 2009, and 2013. All three tests were well above the detection threshold and easily detected and located by the seismic monitoring network. In addition, noble gas consistent with the nuclear tests in 2006 and 2013 (according to atmospheric transport models) was detected by stations in the network. On-site inspections of these tests were not conducted as the Treaty has not entered into force. In order to achieve a credible and trustworthy Verification System, increased focus is being put on the development of OSI operational capabilities while operating and sustaining the existing monitoring system, increasing the data availability and quality, and completing the remaining facilities of the IMS. Furthermore, as mandated by the Treaty, the CTBTO also seeks to continuously improve its technologies and methods through interaction with the scientific community. Workshops and scientific conferences such as the CTBT Science and Technology Conference series provide venues for exchanging ideas, and mechanisms have been developed for sharing IMS data with researchers who are developing and testing new and innovative methods pertinent to the verification regime. While progress is steady on building up the verification regime, there is also progress in gaining entry into force of the Treaty, which requires the signatures and ratifications of the DPRK, India and Pakistan; it also requires the ratifications of China, Egypt, Iran, Israel and the United States. Thirty-six other States, whose signatures and ratifications are needed for entry into force have already done so.

The GEOSCOPE program: state of the art in 2006

NASA Astrophysics Data System (ADS)

Roult, G.; Geoscope Group, A

2006-12-01

The GEOSCOPE program was launched in 1982 by the National Institute of Sciences of Universe (INSU), a department of the French National Center of Scientific Research (CNRS), following the initiative of the Institute of Physics of the Earth of Paris (IPGP). The purpose was the installation of about 25 stations well distributed worldwide (in particular in the southern hemisphere), in the standard configuration defined by the FDSN (very broad-band 24 bit, continuous recording at 20sps). At present, the GEOSCOPE program is operating 28 digital 3-component very- broadband stations. In terms of site locations, the aim of the GEOSCOPE program is almost fulfilled. Our purpose is to maintain the stations at original sites (Indian Ocean, Africa) and to fill some geographical gaps at high latitudes in the southern and northern hemisphere. In particular, we plan to install a new stations VOR (Vorkuta) at high latitudes in Russia and to move the station SEY (Seimchan) to a new location in northern Kamchatka. We are also working on improving data quality and transmission. Historically, GEOSCOPE did not operate real-time data. Continuous data from most of stations arrive with significant delays and records from large events are teletransmitted from some stations (by phone RTC line or through internet) and are made available within one day. To improve this situation, we are replacing the old Streckeisen digitizers with new Quanterra data loggers. This will potentially allow us to receive most of data in our Data Center in a near real-time. Presently data from 8 stations arrive at the IPGP Geoscope Data Center in near real-time, with a delay depending on the station: 1-DZM Dzumac in New Caledonia, a joint DASE/CTBTO/GEOSCOPE station 2-FDF Fort de France in French West Indies 3-SSB Saint Sauveur-Badole in France 4-RER Riviere de l'Est , La Réunion, Indian Ocean 5-KIP Kipapa, Hawaï, a joint USGS/IRIS/GEOSCOPE station 6-TRIS Tristan Da Cunha, a joint USGS/IRIS/GEOSCOPE station 7-TAOE Marquesas Islands, a joint DASE/GEOSCOPE station 8-ATD Arta, Djibouti, a joint CTBTO/CERD/G station The next challenge is to link the maximum number of stations to our Data Center for getting data in real time. To reach this objective in a few years, we plan to upgrade 3 or 4 stations every year, giving priority to the ones easy to link permanently to Paris (TAM/Algeria, SPB/Brasil and CAN/Australia before the end of 2006). For the last ten years we have been progressively installing microbarometers and thermometers, transforming all our stations in multiparameter observatories. We also are participating to the national efforts for the creation of a Tsunami Warning Center at La Reunion Island in the frame of the CNATOI project (Centre National d'Alerte aux Tsunamis dans l'Ocean Indien).

135Xe measurements with a two-element CZT-based radioxenon detector for nuclear explosion monitoring.

PubMed

Ranjbar, Lily; Farsoni, Abi T; Becker, Eric M

2017-04-01

Measurement of elevated concentrations of xenon radioisotopes ( 131m Xe, 133m Xe, 133 Xe and 135 Xe) in the atmosphere has been shown to be a very powerful method for verifying whether or not a detected explosion is nuclear in nature. These isotopes are among the few with enough mobility and with half-lives long enough to make their detection at long distances realistic. Existing radioxenon detection systems used by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) suffer from problems such as complexity, need for high maintenance and memory effect. To study the response of CdZnTe (CZT) detectors to xenon radioisotopes and investigate whether it is capable of mitigating the aforementioned issues with the current radioxenon detection systems, a prototype detector utilizing two coplanar CZT detectors was built and tested at Oregon State University. The detection system measures xenon radioisotopes through beta-gamma coincidence technique by detecting coincidence events between the two detectors. In this paper, we introduce the detector design and report our measurement results with radioactive lab sources and 135 Xe produced in the OSU TRIGA reactor. Minimum Detectable Concentration (MDC) for 135 Xe was calculated to be 1.47 ± 0.05 mBq/m 3 . Copyright © 2017 Elsevier Ltd. All rights reserved.

A prototype detection system for atmospheric monitoring of xenon radioisotopes

NASA Astrophysics Data System (ADS)

Czyz, Steven A.; Farsoni, Abi T.; Ranjbar, Lily

2018-03-01

The design of a radioxenon detection system utilizing a CdZeTe crystal and a plastic scintillator coupled to an array of SiPMs to conduct beta-gamma coincidence detection for atmospheric radioxenon monitoring, as well as the measurement of 135Xe and 133/133mXe, have been detailed previously. This paper presents recent measurements of 133/133mXe and 131mXe and the observation of conversion electrons in their coincidence spectra, as well as a 48-hour background measurement to calculate the Minimum Detectable Concentration (MDC) of radioxenon isotopes in the system. The identification of Regions of Interest (ROIs) in the coincidence spectra yielded from the radioxenon measurements, and the subsequent calculation of the MDCs of the system for 135Xe, 133/133mXe, and 131mXe, are also discussed. Calculated MDCs show that the detection system preforms respectably when compared to other state of the art radioxenon detection systems and achieved an MDC of less than 1 mBq/m3 for 131mXe, 133Xe, and 133mXe, in accordance with limits set by the Comprehensive Nuclear-Test-Ban Treaty (CTBTO). The system also provides the advantage of room temperature operation, compactness, low noise operation and having simple readout electronics.

Engineering and development projects for the sustainment and enhancement of the IMS infrasound network

NASA Astrophysics Data System (ADS)

Marty, J.; Martysevich, P.; Kramer, A.; Haralabus, G.

2012-04-01

The Provisional Technical Secretariat (PTS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has a continuous interest in enhancing its capability in infrasound source localization and characterization. This capability is based on the processing of data recorded by the infrasound network of the International Monitoring System (IMS). This infrasound network consists of sixty stations, among which forty-five are already certified and continuously transmit data to the International Data Center (IDC) in Vienna, Austria. Each infrasound station is composed of an array of infrasound sensors capable of measuring micro-pressure changes produced at ground level by infrasonic waves. It is the responsibility of the Engineering and Development Section of the IMS Division to ensure the highest quality for IMS infrasound data. This includes the design of robust and reliable infrasound stations, the use of accurate and calibrated infrasound measuring chains, the installation of efficient wind noise reduction systems and the implementation of quality-control tools. The purpose of this paper is to present ongoing PTS infrasound engineering and development projects related to the testing and validation of wind noise reduction system models, the implementation of infrasound data QC tools, the definition of guidelines for the design of IMS power supply systems and the development of a portable infrasound calibrator and of field kits for site survey and certification.

NetMOD Version 2.0 User?s Manual.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merchant, Bion J.

2015-10-01

NetMOD ( Net work M onitoring for O ptimal D etection) is a Java-based software package for conducting simulation of seismic, hydracoustic, and infrasonic networks. Specifically, NetMOD simulates the detection capabilities of monitoring networks. Network simulations have long been used to study network resilience to station outages and to determine where additional stations are needed to reduce monitoring thresholds. NetMOD makes use of geophysical models to determine the source characteristics, signal attenuation along the path between the source and station, and the performance and noise properties of the station. These geophysical models are combined to simulate the relative amplitudes ofmore » signal and noise that are observed at each of the stations. From these signal-to-noise ratios (SNR), the probability of detection can be computed given a detection threshold. This manual describes how to configure and operate NetMOD to perform detection simulations. In addition, NetMOD is distributed with simulation datasets for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) International Monitoring System (IMS) seismic, hydroacoustic, and infrasonic networks for the purpose of demonstrating NetMOD's capabilities and providing user training. The tutorial sections of this manual use this dataset when describing how to perform the steps involved when running a simulation. ACKNOWLEDGEMENTS We would like to thank the reviewers of this document for their contributions.« less

Overview of IMS infrasound station and engineering projects

NASA Astrophysics Data System (ADS)

Marty, J.; Doury, B.; Kramer, A.; Martysevich, P.

2015-12-01

The Provisional Technical Secretariat (PTS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBTO) has a continuous interest in enhancing its capability in acoustic source detection, localization and characterization. The infrasound component of the International Monitoring System (IMS) constitutes the only worldwide ground-based infrasound network. It consists of sixty stations, among which forty-eight are already certified and continuously transmit data to the International Data Centre (IDC) in Vienna, Austria. Each infrasound station is composed of an array of infrasound sensors capable of measuring micro-pressure changes produced at ground level by infrasonic waves. The characteristics of infrasonic waves are computed in near real-time by IDC automatic detection software and are used as an input to IDC source categorization and localization algorithms. The PTS is continuously working towards the completion and sustainment of the IMS infrasound network. The objective of this presentation is to review the main activities performed in the IMS infrasound network over the last five years. This includes construction, installation, certification, major upgrade and revalidation activities. Major technology development projects to improve the reliability and robustness of IMS infrasound stations as well as their compliance with IMS Operational Manual requirements will also be presented. This includes advances in array geometry, wind noise reduction, system calibration, meteorological data as well as power and communication infrastructures. Finally the impact of all these changes on the overall detection capability of the IMS infrasound network will be highlighted.

The GEOSCOPE Program: state of the art in 2007

NASA Astrophysics Data System (ADS)

Roult, G.; Stutzmann, E.; Maggi, A.

2007-05-01

The GEOSCOPE program was launched in 1982 by the National Institute of Sciences of Universe (INSU), a department of the French National Center of Scientific Research (CNRS), following the initiative of the Institute of Physics of the Earth of Paris (IPGP). The purpose was the installation of about 25 stations well distributed worldwide (in particular in the southern hemisphere), in the standard configuration defined by the FDSN (very broad-band 24 bit, continuous recording at 20sps). At present, the GEOSCOPE program is operating 28 digital 3-component very- broadband stations. In terms of site locations, the aim of the GEOSCOPE program is almost fulfilled. Our purpose is to maintain the stations at original sites (Indian Ocean, Africa) and to fill some geographical gaps at high latitudes in the southern and northern hemisphere. In particular, at high latitudes in Russia, we plan to install a new station VOR (Vorkuta) and to move the station SEY (Seimchan) to a new location in northern Kamchatka. We are also working on improving data quality and transmission. Historically, GEOSCOPE did not operate real- time data. Continuous data from most of stations arrive with significant delays and records from large events are teletransmitted from some stations (by phone RTC line or through internet) and are made available within one day. To improve this situation, we are replacing the old Streckeisen digitizers with new Quanterra data loggers, essentially Q330-HR ones. Presently data from 13 stations are made available at the IPGP Geoscope Data Center in near real-time, with a delay depending on the station: 1- ATD (Arta, Djibouti), a joint CTBTO/CERD/G station 2- CAN (Canberra, Australia), a joint ANU/G station 3- DZM (Dzumac, New Caledonia, a joint DASE/CTBTO/G station 4- ECH (Echery, France) 5- FDF (Fort de France, French West Indies) 6- KIP (Kipapa, Hawai), a joint IRIS/USGS/G station 7- PAF (Port aux Français, Kerguelen Island) 8- RER (Riviere de l'Est , La Reunion) 9- SSB (Saint Sauveur-Badole, France) 10- SPB (Sao Paulo, Brazil) 11- TAM (Tamanrasset, Algeria) 12- TAOE Marquesas Islands, a joint DASE/G station 13- TRIS Tristan Da Cunha, a joint IRIS/USGS/G station Our challenge is to link the maximum number of stations to our Data Center for getting data in real time. To reach this objective in a few years, we plan to upgrade more than 2 stations every year, our priority in 2007 is the upgrade of stations PEL and COYC in Chile. For the last ten years we have been progressively installing en environmental sensors (microbaromètres, thermometers), transforming all our stations in multiparameter observatories. We also are participating to the national efforts for the creation of a Tsunami Warning Center at La Réunion Island in the frame of the CNATOI project (Centre National d'Alerte aux Tsunamis dans l'Océan Indien). That project includes the installation of two new stations in 2007, one at Rodrigues Island (Mauritius) and one at Fort- Dauphin (NAM station, Madagascar). Daily automatic procedures allow to compute the noise level plots of each component, for each station in near real-time, in order to detect any anomalous behaviour of the station and to follow the station status.

Radionuclide data analysis in connection of DPRK event in May 2009

NASA Astrophysics Data System (ADS)

Nikkinen, Mika; Becker, Andreas; Zähringer, Matthias; Polphong, Pornsri; Pires, Carla; Assef, Thierry; Han, Dongmei

2010-05-01

The seismic event detected in DPRK on 25.5.2009 was triggering a series of actions within CTBTO/PTS to ensure its preparedness to detect any radionuclide emissions possibly linked with the event. Despite meticulous work to detect and verify, traces linked to the DPRK event were not found. After three weeks of high alert the PTS resumed back to normal operational routine. This case illuminates the importance of objectivity and procedural approach in the data evaluation. All the data coming from particulate and noble gas stations were evaluated daily, some of the samples even outside of office hours and during the weekends. Standard procedures were used to determine the network detection thresholds of the key (CTBT relevant) radionuclides achieved across the DPRK event area and for the assessment of radionuclides typically occurring at IMS stations (background history). Noble gas system has sometimes detections that are typical for the sites due to legitimate non-nuclear test related activities. Therefore, set of hypothesis were used to see if the detection is consistent with event time and location through atmospheric transport modelling. Also the consistency of event timing and isotopic ratios was used in the evaluation work. As a result it was concluded that if even 1/1000 of noble gasses from a nuclear detonation would had leaked, the IMS system would not had problems to detect it. This case also showed the importance of on-site inspections to verify the nuclear traces of possible tests.

Infrasound workshop for CTBT monitoring: Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christie, D.; Whitaker, R.

1998-11-01

It is expected that the establishment of new infrasound stations in the global IMS network by the Provisional Technical Secretariat of the CTBTO in Vienna will commence in the middle of 1998. Thus, decisions on the final operational design for IMS infrasound stations will have to be made within the next 12 months. Though many of the basic design problems have been resolved, it is clear that further work needs to be carried out during the coming year to ensure that IMS infrasound stations will operate with maximum capability in accord with the specifications determined during the May 1997 PrepCommore » Meeting. Some of the papers presented at the Workshop suggest that it may be difficult to design a four-element infrasound array station that will reliably detect and locate infrasound signals at all frequencies in the specified range from 0.02 to 4.0 Hz in all noise environments. Hence, if the basic design of an infrasound array is restricted to four array elements, the final optimized design may be suited only to the detection and location of signals in a more limited pass-band. Several participants have also noted that the reliable discrimination of infrasound signals could be quite difficult if the detection system leads to signal distortion. Thus, it has been emphasized that the detection system should not, if possible, compromise signal fidelity. This report contains the workshop agenda, a list of participants, and abstracts and viewgraphs from each presentation.« less

Optimizing detection of noble gas emission at a former UNE site: sample strategy, collection, and analysis

NASA Astrophysics Data System (ADS)

Kirkham, R.; Olsen, K.; Hayes, J. C.; Emer, D. F.

2013-12-01

Underground nuclear tests may be first detected by seismic or air samplers operated by the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization). After initial detection of a suspicious event, member nations may call for an On-Site Inspection (OSI) that in part, will sample for localized releases of radioactive noble gases and particles. Although much of the commercially available equipment and methods used for surface and subsurface environmental sampling of gases can be used for an OSI scenario, on-site sampling conditions, required sampling volumes and establishment of background concentrations of noble gases require development of specialized methodologies. To facilitate development of sampling equipment and methodologies that address OSI sampling volume and detection objectives, and to collect information required for model development, a field test site was created at a former underground nuclear explosion site located in welded volcanic tuff. A mixture of SF-6, Xe127 and Ar37 was metered into 4400 m3 of air as it was injected into the top region of the UNE cavity. These tracers were expected to move towards the surface primarily in response to barometric pumping or through delayed cavity pressurization (accelerated transport to minimize source decay time). Sampling approaches compared during the field exercise included sampling at the soil surface, inside surface fractures, and at soil vapor extraction points at depths down to 2 m. Effectiveness of various sampling approaches and the results of tracer gas measurements will be presented.

Upper mantle seismic anisotropy beneath Northern Peru from shear wave splitting analysis.

NASA Astrophysics Data System (ADS)

Franca, G. S.; Condori, C.; Tavera, H.; Eakin, C. M.; Beck, S. L.

2017-12-01

Beneath much of Peru lies the largest region of flat-slab subduction in the world today. The origins and dynamics of the Peruvian flat-slab however remain elusive, particularly in the north away from the Nazca Ridge. Studies of seismic anisotropy can potentially provide us with insight into the dynamics of recent and past deformational processes in the upper mantle. In this study, we conduct shear wave splitting to investigate seismic anisotropy across the northern extent of the Peruvian flat-slab for the first time. For the analysis, we used arrivals of SKS, SKKS and PKS phases from teleseismic events (88° > Δ < 150°) recorded at 30 broadband seismic stations from the Peruvian permanent and portable seismic networks, and international networks (CTBTO and RSBR-Brazil). The preliminary results reveal a complex anisotropy pattern with variations along strike. In the northernmost region, the average delay times range between 1.0 s and 1.2 s, with fast directions predominantly ENE-WSW oriented in a direction approximately perpendicular to the trench, parallel with subduction of the Nazca plate. Meanwhile towards the central region of Peru, the predominant fast direction changes to SE-NW oblique with the trench, but consistent with the pattern seen previously over the southern extent of the flat-slab by Eakin et al. (2013, 2015). These characteristics suggest a fundamental difference between the anisotropic structures, and therefore underlying mantle processes, beneath the northern and central portions of the Peruvian flat-slab.

A General Investigation of Optimized Atmospheric Sample Duration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eslinger, Paul W.; Miley, Harry S.

2012-11-28

ABSTRACT The International Monitoring System (IMS) consists of up to 80 aerosol and xenon monitoring systems spaced around the world that have collection systems sensitive enough to detect nuclear releases from underground nuclear tests at great distances (CTBT 1996; CTBTO 2011). Although a few of the IMS radionuclide stations are closer together than 1,000 km (such as the stations in Kuwait and Iran), many of them are 2,000 km or more apart. In the absence of a scientific basis for optimizing the duration of atmospheric sampling, historically scientists used a integration times from 24 hours to 14 days for radionuclidesmore » (Thomas et al. 1977). This was entirely adequate in the past because the sources of signals were far away and large, meaning that they were smeared over many days by the time they had travelled 10,000 km. The Fukushima event pointed out the unacceptable delay time (72 hours) between the start of sample acquisition and final data being shipped. A scientific basis for selecting a sample duration time is needed. This report considers plume migration of a nondecaying tracer using archived atmospheric data for 2011 in the HYSPLIT (Draxler and Hess 1998; HYSPLIT 2011) transport model. We present two related results: the temporal duration of the majority of the plume as a function of distance and the behavior of the maximum plume concentration as a function of sample collection duration and distance. The modeled plume behavior can then be combined with external information about sampler design to optimize sample durations in a sampling network.« less

Global atmospheric monitoring of noble gases: insight into transport processes in the southern hemisphere.

NASA Astrophysics Data System (ADS)

Kusmierczyk-Michulec, J.; Kalinowski, M.; Bourgouin, P.; Schoeppner, M.

2017-12-01

The International Monitoring System (IMS) developed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is a global system of monitoring stations, using four complementary technologies: seismic, hydroacoustic, infrasound and radionuclide. Data from all stations, belonging to IMS, are collected and transmitted to the International Data Centre (IDC) in Vienna, Austria. The radionuclide network comprises 80 stations, of which 31 stations are located in the Southern Hemisphere. The aim of radionuclide stations is a global monitoring of radioactive aerosols and radioactive noble gases supported by atmospheric transport modeling (ATM). The air mass trajectory provides a "link" between a radionuclide release and a detection confirmed by radionuclide measurements. One of the important noble gases, monitored on a daily basis, is xenon. It can be produced either during a nuclear explosion with a high fission yield, and thus be considered as an important tracer to prove the nuclear character of an explosion, or be emitted from nuclear power plants (NPPs) or from isotope production facilities (IPFs). On the southern hemisphere the number of IPF is rather limited in comparison to the northern hemisphere. Among the major sources are: the ANSTO facility in Sydney (Australia), CNEA in Ezeiza (Argentina), BaTek/INUKI in Jakarta (Indonesia) and NECSA in Pelindaba (South Africa). This study will demonstrate the examples of seasonal contribution of Xe-133 emissions from major sources as observed at selected IMS stations located in the southern hemisphere. It will show as well examples of the atmospheric transport from the northern to the southern hemisphere, and the influence of strong atmospheric convection.

Crustal structure of north Peru from analysis of teleseismic receiver functions

NASA Astrophysics Data System (ADS)

Condori, Cristobal; França, George S.; Tavera, Hernando J.; Albuquerque, Diogo F.; Bishop, Brandon T.; Beck, Susan L.

2017-07-01

In this study, we present results from teleseismic receiver functions, in order to investigate the crustal thickness and Vp/Vs ratio beneath northern Peru. A total number of 981 receiver functions were analyzed, from data recorded by 28 broadband seismic stations from the Peruvian permanent seismic network, the regional temporary SisNort network and one CTBTO station. The Moho depth and average crustal Vp/Vs ratio were determined at each station using the H-k stacking technique to identify the arrival times of primary P to S conversion and crustal reverberations (PpPms, PpSs + PsPms). The results show that the Moho depth correlates well with the surface topography and varies significantly from west to east, showing a shallow depth of around 25 km near the coast, a maximum depth of 55-60 km beneath the Andean Cordillera, and a depth of 35-40 km further to the east in the Amazonian Basin. The bulk crustal Vp/Vs ratio ranges between 1.60 and 1.88 with the mean of 1.75. Higher values between 1.75 and 1.88 are found beneath the Eastern and Western Cordilleras, consistent with a mafic composition in the lower crust. In contrast values vary from 1.60 to 1.75 in the extreme flanks of the Eastern and Western Cordillera indicating a felsic composition. We find a positive relationship between crustal thickness, Vp/Vs ratio, the Bouguer anomaly, and topography. These results are consistent with previous studies in other parts of Peru (central and southern regions) and provide the first crustal thickness estimates for the high cordillera in northern Peru.

Acoustic wave simulation using an overset grid for the global monitoring system

NASA Astrophysics Data System (ADS)

Kushida, N.; Le Bras, R.

2017-12-01

The International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has been monitoring hydro-acoustic and infrasound waves over the globe. Because of the complex natures of the oceans and the atmosphere, computer simulation can play an important role in understanding the observed signals. In this regard, methods which depend on partial differential equations and require minimum modelling, are preferable. So far, to our best knowledge, acoustic wave propagation simulations based on partial differential equations on such a large scale have not been performed (pp 147 - 161 of ref [1], [2]). The main difficulties in building such simulation codes are: (1) considering the inhomogeneity of medium including background flows, (2) high aspect ratio of computational domain, (3) stability during long time integration. To overcome these difficulties, we employ a two-dimensional finite different (FDM) scheme on spherical coordinates with the Yin-Yang overset grid[3] solving the governing equation of acoustic waves introduces by Ostashev et. al.[4]. The comparison with real recording examples in hydro-acoustic will be presented at the conference. [1] Paul C. Etter: Underwater Acoustic Modeling and Simulation, Fourth Edition, CRC Press, 2013. [2] LIAN WANG et. al.: REVIEW OF UNDERWATER ACOUSTIC PROPAGATION MODELS, NPL Report AC 12, 2014. [3] A. Kageyama and T. Sato: "Yin-Yang grid": An overset grid in spherical geometry, Geochem. Geophys. Geosyst., 5, Q09005, 2004. [4] Vladimir E. Ostashev et. al: Equations for finite-difference, time-domain simulation of sound propagation in moving inhomogeneous media and numerical implementation, Acoustical Society of America. DOI: 10.1121/1.1841531, 2005.

Recognizing explosion sites with a self-organizing network for unsupervised learning

NASA Astrophysics Data System (ADS)

Tarvainen, Matti

1999-06-01

A self-organizing neural network model has been developed for identifying mining explosion locations in different environments in Finland and adjacent areas. The main advantage of the method is its ability to automatically find a suitable network structure and naturally correctly identify explosions as such. The explosion site recognition was done using extracted waveform attributes of various kind event records from the small-aperture array FINESS in Finland. The recognition was done by using P-S phase arrival differences and rough azimuth estimates to provide a first robust epicentre location. This, in turn, leads to correct mining district identification where more detailed tuning was performed using different phase amplitude and signal-to-noise attributes. The explosions studied here originated in mines and quarries located in Finland, coast of Estonia and in the St. Petersburg area, Russia. Although the Helsinki bulletins in 1995 and 1996 listed 1649 events in these areas, analysis was restricted to the 380 (ML≥2) events which, besides, were found in the reviewed event bulletins (REB) of the CTBTO/UN prototype international data centre (pIDC) in Arlington, VA, USA. These 380 events with different attributes were selected for the learning stage. Because no `ground-truth' information was available the corresponding mining, `code' coordinates used earlier to compile Helsinki bulletins were utilized instead. The novel self-organizing method was tested on 18 new event recordings in the mentioned area in January-February 1997, out of which 15 were connected to correct mines. The misconnected three events were those which did not have all matching attributes in the self-organizing maps (SOMs) network.

Alteration of natural (37)Ar activity concentration in the subsurface by gas transport and water infiltration.

PubMed

Guillon, Sophie; Sun, Yunwei; Purtschert, Roland; Raghoo, Lauren; Pili, Eric; Carrigan, Charles R

2016-05-01

High (37)Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of (37)Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict (37)Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating (37)Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for (37)Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural (37)Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of (37)Ar activity concentrations. The influence of soil water content on (37)Ar production is shown to be negligible to first order, while (37)Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interactive Model Visualization for NET-VISA

NASA Astrophysics Data System (ADS)

Kuzma, H. A.; Arora, N. S.

2013-12-01

NET-VISA is a probabilistic system developed for seismic network processing of data measured on the International Monitoring System (IMS) of the Comprehensive nuclear Test Ban Treaty Organization (CTBTO). NET-VISA is composed of a Generative Model (GM) and an Inference Algorithm (IA). The GM is an explicit mathematical description of the relationships between various factors in seismic network analysis. Some of the relationships inside the GM are deterministic and some are statistical. Statistical relationships are described by probability distributions, the exact parameters of which (such as mean and standard deviation) are found by training NET-VISA using recent data. The IA uses the GM to evaluate the probability of various events and associations, searching for the seismic bulletin which has the highest overall probability and is consistent with a given set of measured arrivals. An Interactive Model Visualization tool (IMV) has been developed which makes 'peeking into' the GM simple and intuitive through a web-based interfaced. For example, it is now possible to access the probability distributions for attributes of events and arrivals such as the detection rate for each station for each of 14 phases. It also clarifies the assumptions and prior knowledge that are incorporated into NET-VISA's event determination. When NET-VISA is retrained, the IMV will be a visual tool for quality control both as a means of testing that the training has been accomplished correctly and that the IMS network has not changed unexpectedly. A preview of the IMV will be shown at this poster presentation. Homepage for the IMV IMV shows current model file and reference image.

Long- range transport of Xe-133 emissions under convective and non-convective conditions.

NASA Astrophysics Data System (ADS)

Kusmierczyk-Michulec, Jolanta; Gheddou, Abdelhakim

2015-04-01

The International Monitoring System (IMS) developed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is a global system of monitoring stations, using four complementary technologies: seismic, hydroacoustic, infrasound and radionuclide. Data from all stations, belonging to IMS, are collected and transmitted to the International Data Centre (IDC) in Vienna, Austria. The radionuclide network comprises 80 stations, of which more than 60 are certified. The aim of radionuclide stations is a global monitoring of radioactive aerosols and radioactive noble gases, in particular xenon isotopes, supported by the atmospheric transport modeling (ATM). The aim of this study is to investigate the long-range transport of Xe-133 emissions under convective and non-convective conditions. For that purpose a series of 14 days forward simulations was conducted using the Lagrangian Particle Diffusion Model FLEXPART, designed for calculating the long-range and mesoscale dispersion of air pollution from point sources. The release point was at the ANSTO facility in Australia. The geographical localization to some extent justifies the assumption that the only source of Xe-133 observed at the neighbouring stations, comes from the ANSTO facility. In the simulations the analysed wind data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) were used with the spatial resolution of 0.5 degree. Studies have been performed to link Xe-133 emissions with detections at the IMS stations supported by the ATM, and to assess the impact of atmospheric convection on non-detections at the IMS stations. The results of quantitative and qualitative comparison will be presented.

2013 certified IMS infrasound stations: IS37 (Bardufoss, Norway) and IS58 (Midway, USA)

NASA Astrophysics Data System (ADS)

Haralabus, Georgios; Marty, Julien; Kramer, Alfred; Mialle, Pierrick; Robertson, James

2014-05-01

The Infrasound component of the International Monitoring System (IMS) of the Comprehensive Nuclear?Test?Ban Treaty Organization (CTBTO) includes 60 infrasound stations out of which 47 are currently certified. The latest two additions to this Infrasound network, namely IS58 on Sand Island, Midway Atoll, United States of America (USA), and IS37 in Bardufoss, Norway, are presented here. Both stations were certified in 2013. IS58 is a 4 element infrasound array arranged in a triangular geometry with a central component. The triangular bases vary from 1.1 to 1.8 km. The micropressure sensors deployed at each element were Chaparral 50A microbarometers. Signals from IS58 were processed by the International Data Centre (IDC) and detection associated not only with microbaroms but also with the activity of the Kliuchevskoi volcano in the Russian Peninsula Kamchatka were built. These initial results indicate good detection capability of the IS58 station for low wind conditions. In Norway the topography allowed for a large element array, so IS37 was built with 10-elements that have average spacing of 1 km. This design allows the formation of several triangles with baseline of 1 to 2 km and also a triangular sub array with spacing of approximately 360 m. The sensors utilized in IS37 elements were MB2005 microbarometers. Initial data analysis by IDC identified distant microbarom sources with strong azimuth and frequency content variability as well as strong detections from local sources, namely the Finnfjord ferro-alloy plant in Norway and the Kiruna iron mine in Sweden.

Testing of the KRI-developed Silicon PIN Radioxenon Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foxe, Michael P.; McIntyre, Justin I.

Radioxenon detectors are used for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in a network of detectors throughout the world called the International Monitoring System (IMS). The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) Provisional Technical Secretariat (PTS) has tasked Pacific Northwest National Laboratory (PNNL) with testing a V.G. Khlopin Radium Institute (KRI) and Lares Ltd-developed Silicon PIN detector for radioxenon detection. PNNL measured radioxenon with the silicon PIN detector and determined its potential compared to current plastic scintillator beta cells. While the PNNL tested Si detector experienced noise issues, a second detector was tested in Russia at Lares Ltd, whichmore » did not exhibit the noise issues. Without the noise issues, the Si detector produces much better energy resolution and isomer peak separation than a conventional plastic scintillator cell used in the SAUNA systems in the IMS. Under the assumption of 1 cm 3 of Xe in laboratory-like conditions, 24-hr count time (12-hr count time for the SAUNA), with the respective shielding the minimum detectable concentrations for the Si detector tested by Lares Ltd (and a conventional SAUNA system) were calculated to be: 131mXe – 0.12 mBq/m 3 (0.12 mBq/m 3); 133Xe – 0.18 mBq/m 3 (0.21 mBq/m 3); 133mXe – 0.07 mBq/m 3 (0.15 mBq/m 3); 135Xe – 0.45 mBq/m 3 (0.67 mBq/m 3). Detection limits, which are one of the important factors in choosing the best detection technique for radioxenon in field conditions, are significantly better than for SAUNA-like detection systems for 131mXe and 133mXe, but similar for 133Xe and 135Xe. Another important factor is the amount of “memory effect” or carry over signal from one radioxenon measurement to the subsequent sample. The memory effect is reduced by a factor of 10 in the Si PIN detector compared to the current plastic scintillator cells. There is potential for further reduction with the removal of plastics within the cell, which will need to be explored in future work. A third important parameter in choosing the best detection technique for radioxenon is the resolution of the electron detection. While the resolution is important in determining the minimum detectable concentration, it plays a larger role in source identification when there is a visible signal. The Silicon PIN diodes generated improved resolution over a similar plastic scintillator cell. With the improved resolution, it becomes easier to distinguish the radioxenon isomers ( 133mXe and 131mXe) from the 133Xe beta continuum background. With the beta background from 133Xe ever present with the detection of the isomers, the improved resolution proves vital in calculating the ratios of the three isotopes. With an accurate measurement of the isotopic ratios, the anthropogenic sources of radioxenon (medical isotope production and nuclear reactors) can be more accurately distinguished. Based on the results shown within this report, a Si PIN beta cell shows the potential to aid in the operation and discriminating power of the IMS for the CTBTO. However, there are a number of issues that need attention before a detector of this design would be reliable enough for field operations in the IMS. Issues that need develop include, but are not limited to: studying the robustness of the design in field conditions, eliminating or minimizing the noise and variability of individual Si detector elements, understanding the long-term gain stability of the Si detectors, and reducing the non-Si materials within the cell (i.e. the plastic housing).« less

Seismic Search Engine: A distributed database for mining large scale seismic data

NASA Astrophysics Data System (ADS)

Liu, Y.; Vaidya, S.; Kuzma, H. A.

2009-12-01

The International Monitoring System (IMS) of the CTBTO collects terabytes worth of seismic measurements from many receiver stations situated around the earth with the goal of detecting underground nuclear testing events and distinguishing them from other benign, but more common events such as earthquakes and mine blasts. The International Data Center (IDC) processes and analyzes these measurements, as they are collected by the IMS, to summarize event detections in daily bulletins. Thereafter, the data measurements are archived into a large format database. Our proposed Seismic Search Engine (SSE) will facilitate a framework for data exploration of the seismic database as well as the development of seismic data mining algorithms. Analogous to GenBank, the annotated genetic sequence database maintained by NIH, through SSE, we intend to provide public access to seismic data and a set of processing and analysis tools, along with community-generated annotations and statistical models to help interpret the data. SSE will implement queries as user-defined functions composed from standard tools and models. Each query is compiled and executed over the database internally before reporting results back to the user. Since queries are expressed with standard tools and models, users can easily reproduce published results within this framework for peer-review and making metric comparisons. As an illustration, an example query is “what are the best receiver stations in East Asia for detecting events in the Middle East?” Evaluating this query involves listing all receiver stations in East Asia, characterizing known seismic events in that region, and constructing a profile for each receiver station to determine how effective its measurements are at predicting each event. The results of this query can be used to help prioritize how data is collected, identify defective instruments, and guide future sensor placements.

Prospects for infrasound bolide detections from balloon-borne platforms

NASA Astrophysics Data System (ADS)

Young, Eliot; Bowman, Daniel; Arrowsmith, Stephen; Boslough, Marc; Klein, Viliam; Ballard, Courtney; Lees, Jonathan

2017-04-01

We report on an experiment to assess whether balloon-borne instruments can improve sensitivities to bolides exploding in the Earth's atmosphere (essentially using the atmosphere as a witness plate to characterize the small end of the NEO (Near Earth Object) population). The CTBTO's infrasound network regularly detects infrasound disturbances caused by bolides, including the 15-FEB-2013 Chelybinsk impact. Balloon-borne infrasound sensors should have two important advantages over ground-based infrasound stations: there should be virtually no wind noise on a free-floating platform, and a sensor in the stratosphere should benefit from its location within the stratospheric duct. Balloon-borne sensors also have the disadvantage that the amplitude of infrasound waves will decrease as they ascend with altitude. To test the performance of balloon-borne sensors, we conducted an experiment on a NASA high altitude (35 km) balloon launched from Ft Sumner, NM on 28-SEP-2016. We were able to put two independent infrasound payloads on this flight. We arranged for three 3000-lb ANFO explosions to be detonated from Socorro, NM at 12:00, 14:00 and 16:29:59 MST. The first two explosions were detected from the NASA balloon, with the first explosion showing three separate waveforms arriving within a 25-s span. The peak-to-peak amplitude of the waveforms was about 0.06 Pa, and the cleanest microphone channel detected this waveform with an SNR greater than 20. A second balloon at 15 km altitude also detected the second explosion. We have signals from a dozen ground stations at various positions from Socorro to Ft Sumner. We will report on wave propagation models and how they compare with observations from the two balloons and the various ground-stations.

Seismic Analysis of Three Bomb Explosions in Turkey

NASA Astrophysics Data System (ADS)

Necmioglu, O.; Semin, K. U.; Kocak, S.; Destici, C.; Teoman, U.; Ozel, N. M.

2016-12-01

Seismic analysis of three vehicle-installed bomb explosions occurred on 13 March 2016 in Ankara, 12 May 2016 in Diyarbakır and 9 July 2016 in Mardin have been conducted using data from the nearest stations (LOD, DYBB and MAZI) of the Boğaziçi University - Kandilli Observatory and Earthquake Research Institute's (KOERI) seismic network and compared with low-magnitude earthquakes in similar distance based on phase readings and frequency content. Amplitude spectra has been compared through Fourier transformation and earthquake-explosion frequency discrimination has been performed using various filter bands. Time-domain and spectral analysis have been performed using Geotool software provided by CTBTO. Local magnitude (ML) values have been calculated for each explosion by removing instrument-response and adding Wood-Anderson type instrument response. Approximate amount of explosives used in these explosions have been determined using empirical methods of Koper (2002). Preliminary results indicated that 16 tons TNT equivalent explosives have been used in 12 May 2016 Diyarbakır explosion, which is very much in accordance with the media reports claiming 15 tons of TNT. Our analysis for 9 July 2016 Mardin explosion matched the reported 5 tons of explosives. Results concerning 13 March 2016 Ankara explosion indicated that approximately 1,7 ton of TNT equivalent explosives were used in the attack whereas security and intelligence reports claimed 300 kg explosives as a combination of TNT, RDX and ammonium nitrate. The overestimated results obtained in our analysis for the Ankara explosion may be related due to i) high relative effectiveness factor of the RDX component of the explosive ii) inefficiency of Koper (2002) method in lower yields (since the method was developed using explosions with yields of 3-12 tons of TNT), iii) combination of both.

Infrasound from lightning measured in Ivory Coast

NASA Astrophysics Data System (ADS)

Farges, T.; Matoza, R. S.

2011-12-01

It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. More than two thirds (42) of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes, ...). Some of the IMS stations are located where worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS infrasound station has been installed in Ivory Coast for 8 years. The optical space-based instrument OTD measured a rate of 10-20 flashes/km^2/year in that country and showed strong seasonal variations (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 3 years of data (2005-2008).

Setting up infrasonic propagation simulation using the latest real-time atmospheric specifications at the IDC

NASA Astrophysics Data System (ADS)

Brachet, N.; Mialle, P.; Brown, D.; Coyne, J.; Drob, D.; Virieux, J.; Garcés, M.

2009-04-01

The International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty (CTBTO) Preparatory Commission in Vienna is pursuing its automatic processing effort for the return of infrasound data processing into operations in 2009. Concurrently, work is also underway to further improve this process by enhancing the modeling of the infrasound propagation in the atmosphere and then by labeling the phases in order to improve the event categorization and location. In 2008, the IDC acquired WASP-3D Sph (Windy Atmospheric Sonic Propagation) (Virieux et al., 2004) a 3-D ray-tracing based long range propagation software that accounts for the heterogeneity of the atmosphere. Once adapted to the IDC environment, WASP-3 Sph has been used to improve the understanding of infrasound wave propagation and has been compared with the 1-D ray tracing Taupc software (Garcés and Drob, 2007) at the IDC. In addition to performing the infrasound propagation simulation, different atmospheric models are available at the IDC, either real-time: ECMWF (European Centre for Middle-range Weather Forecast), or empiric: HWM93 (Horizontal Wind Model) and HWM07 (Drob, 2008), used in their initial format or interpolated into G2S (Ground to Space) model. The IDC infrasound reference database is used for testing, comparing and validating the various propagation software and atmospheric specifications. Moreover all the performed simulations are giving feedback on the quality of the infrasound reference events and provide useful information to improve their location by refining infrasonic wave propagation characteristics. The results of this study are presented for a selection of reference events and they will help the IDC designing and defining short and mid-term enhancements of the infrasound automatic and interactive processing to take into account the spatial and temporal heterogeneities of the atmosphere.

Convective transport in ATM simulations and its relation to the atmospheric stability conditions

NASA Astrophysics Data System (ADS)

Kusmierczyk-Michulec, Jolanta

2017-04-01

The International Monitoring System (IMS) developed by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is a global system of monitoring stations, using four complementary technologies: seismic, hydroacoustic, infrasound and radionuclide. Data from all stations, belonging to IMS, are collected and transmitted to the International Data Centre (IDC) in Vienna, Austria. The radionuclide network comprises 80 stations, of which more than 60 are certified. The aim of radionuclide stations is a global monitoring of radioactive aerosols and radioactive noble gases, in particular xenon isotopes, supported by the atmospheric transport modeling (ATM). One of the important noble gases, monitored on a daily basis, is radioxenon. It can be produced either during a nuclear explosion with a high fission yield, and thus be considered as an important tracer to prove the nuclear character of an explosion, or be emitted from nuclear power plants (NPPs) or from isotope production facilities (IPFs). To investigate the transport of xenon emissions, the Provisional Technical Secretariat (PTS) operates an Atmospheric Transport Modelling (ATM) system based on the Lagrangian Particle Dispersion Model FLEXPART. To address the question whether including the convective transport in ATM simulations will change the results significantly, the differences between the outputs with the convective transport turned off and turned on, were computed and further investigated taking into account the atmospheric stability conditions. For that purpose series of 14 days forward simulations, with convective transport and without it, released daily in the period January 2011 to February 2012, were analysed. The release point was at the ANSTO facility in Australia. The unique opportunity of having access to both daily emission values for ANSTO as well as measured Xe-133 activity concentration (AC) values at the IMS stations, gave a chance to validate the simulations.

The ISC Contribution to Monitoring Research

NASA Astrophysics Data System (ADS)

Storchak, D. A.; Bondar, I.; Harris, J.; Gaspà Rebull, O.

2010-12-01

The International Seismological Centre (ISC) is a non-governmental organization charged with production of the ISC Bulletin - the definitive global summary of seismicity based on reports from over 4.5 thousand seismic stations worldwide. The ISC data have been extensively used in preparation of the Comprehensive Test Ban Treaty (CTBT). They are now used by the CTBTO Preparatory Technical Secretariat (PTS) and the State Parties as an important benchmark for assessing and monitoring detection capabilities of the International Monitoring System (IMS). The ISC also provides a valuable collection of reviewed waveform readings at academic and operational sites co-located with the IMS stations. To improve the timeliness of its Bulletin, the ISC is making a special effort in collecting preliminary bulletins from a growing number of networks worldwide that become available soon after seismic events occur. Preliminary bulletins are later substituted with the final analysis data once these become available to the ISC from each network. The ISC also collects and maintains data sets that are useful for monitoring research. These are the IASPEI Reference Event List of globally distributed GT0-5 events, the groomed ISC bulletin (EHB), the IDC REB, USArray phase picking data. In cooperation with the World Data Center for Seismology, Denver (USGS), the ISC also maintains the International Seismographic Station Registry that holds parameters of seismic stations used in the international data exchange. The UK Foreign and Commonwealth Office along with partners from several Nordic countries are currently funding a project to make the ISC database securely linked with the computer facilities at PTS and National Data Centres. The ISC Bulletin data are made available via a dedicated software link designed to offer the ISC data in a way convenient to monitoring community.

Seismo-acoustic Signals Recorded at KSIAR, the Infrasound Array Installed at PS31

NASA Astrophysics Data System (ADS)

Kim, T. S.; Che, I. Y.; Jeon, J. S.; Chi, H. C.; Kang, I. B.

2014-12-01

One of International Monitoring System (IMS)'s primary seismic stations, PS31, called Korea Seismic Research Station (KSRS), was installed around Wonju, Korea in 1970s. It has been operated by US Air Force Technical Applications Center (AFTAC) for more than 40 years. KSRS is composed of 26 seismic sensors including 19 short period, 6 long period and 1 broad band seismometers. The 19 short period sensors were used to build an array with a 10-km aperture while the 6 long period sensors were used for a relatively long period array with a 40-km aperture. After KSRS was certified as an IMS station in 2006 by Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), Korea Institute of Geoscience and Mineral Resources (KIGAM) which is the Korea National Data Center started to take over responsibilities on the operation and maintenance of KSRS from AFTAC. In April of 2014, KIGAM installed an infrasound array, KSIAR, on the existing four short period seismic stations of KSRS, the sites KS05, KS06, KS07 and KS16. The collocated KSIAR changed KSRS from a seismic array into a seismo-acoustic array. The aperture of KSIAR is 3.3 km. KSIAR also has a 100-m small aperture infrasound array at KS07. The infrasound data from KSIAR except that from the site KS06 is being transmitted in real time to KIGAM with VPN and internet line. An initial analysis on seismo-acoustic signals originated from local and regional distance ranges has been performed since May 2014. The analysis with the utilization of an array process called Progressive Multi-Channel Correlation (PMCC) detected seismo-acoustic signals caused by various sources including small explosions in relation to constructing local tunnels and roads. Some of them were not found in the list of automatic bulletin of KIGAM. The seismo-acoustic signals recorded by KSIAR are supplying a useful information for discriminating local and regional man-made events from natural events.

Constraining shallow seismic event depth via synthetic modeling for Expert Technical Analysis at the IDC

NASA Astrophysics Data System (ADS)

Stachnik, J.; Rozhkov, M.; Baker, B.; Bobrov, D.; Friberg, P. A.

2015-12-01

Depth of event is an important criterion of seismic event screening at the International Data Center, CTBTO. However, a thorough determination of the event depth can be conducted mostly through special analysis because the IDC's Event Definition Criteria is based, in particular, on depth estimation uncertainties. This causes a large number of events in the Reviewed Event Bulletin to have depth constrained to the surface. When the true origin depth is greater than that reasonable for a nuclear test (3 km based on existing observations), this may result in a heavier workload to manually distinguish between shallow and deep events. Also, IDC depth criterion is not applicable to the events with the small t(pP-P) travel time difference, which is the case of the nuclear test. Since the shape of the first few seconds of signal of very shallow events is very sensitive to the presence of the depth phase, cross correlation between observed and theoretic seismogram can provide an estimate for the depth of the event, and so provide an expansion to the screening process. We exercised this approach mostly with events at teleseismic and partially regional distances. We found that such approach can be very efficient for the seismic event screening process, with certain caveats related mostly to the poorly defined crustal models at source and receiver which can shift the depth estimate. We used adjustable t* teleseismic attenuation model for synthetics since this characteristic is not determined for most of the rays we studied. We studied a wide set of historical records of nuclear explosions, including so called Peaceful Nuclear Explosions (PNE) with presumably known depths, and recent DPRK nuclear tests. The teleseismic synthetic approach is based on the stationary phase approximation with Robert Herrmann's hudson96 program, and the regional modelling was done with the generalized ray technique by Vlastislav Cerveny modified to the complex source topography.

Recent enhancements of the PMCC infrasound signal detector

NASA Astrophysics Data System (ADS)

Brachet, N.; Mialle, P.; Matoza, R. S.; Le Pichon, A.; Cansi, Y.; Ceranna, L.

2010-12-01

The Progressive Multi-Channel Correlation (PMCC) is an antenna technique that is commonly being used by the scientific community for detecting coherent signals recorded on infrasound arrays. The PMCC detector, originally developed by CEA/DASE (Cansi, 1995), was installed in 2004 in the operational environment of the International Data Centre (IDC) of the Comprehensive nuclear Test Ban Treaty Organization (CTBTO) in Vienna. During the last 5 years, several changes have been made by the IDC to enhance the PMCC source code and parameter configuration, and the detector has exhibited good performance in terms of detection sensitivity and robustness. Recent studies performed at the CEA/DASE have shown that the IDC version (DFX/Geotool-PMCC) and the DASE version (WinPMCC) of PMCC software benefit from the implementation of the adaptive processing window duration and a log-spaced frequency bands. This tested configuration enables better detection and characterization of all received signals in their wave-front parameter space (e.g., frequency-azimuth space, frequency-trace-velocity space). A new release of the WinPMCC software - running under Windows or Linux operating systems - including a fully configurable filtering and detection parameters is now available upon request. We present the results of a statistical analysis on 10 years of infrasound data recorded at the IMS stations IS26, Germany and IS22, New Caledonia. A comparison is made between the automatic detections produced by the IDC, and the reprocessed detections using the optimized filtering and detection configuration parameters. Work is also underway at the CEA/DASE to determine more rigorously the azimuth and speed uncertainties. The current algorithm estimates the uncertainties based on statistical analysis of the distribution of PMCC detection pixels in the azimuth-speed space. The new code that is being considered performs the calculation of infrasound measurement errors as a function of physical parameters, i.e. dependant on the array geometry and the wave properties.

Infrasound from lightning: characteristics and impact on an infrasound station

NASA Astrophysics Data System (ADS)

Farges, Thomas; Blanc, Elisabeth

2010-05-01

More than two third of the infrasound stations of the International Monitoring System (IMS) of the CTBTO are now certified and measure routinely signals due particularly to natural activity (swell, volcano, severe weather including lightning, …). It is well established that more than 2,000 thunderstorms are continuously active all around the world and that about 45 lightning flashes are produced per second over the globe. During the Eurosprite 2005 campaign, we took the opportunity to measure, in France during summer, infrasound from lightning and from sprites (which are transient luminous events occurring over thunderstorm). We examine the possibility to measure infrasound from lightning when thunderstorms are close or far from the infrasound station. Main results concern detection range of infrasound from lightning, amplitude vs. distance law, and characteristics of frequency spectrum. We show clearly that infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. In good noise conditions, infrasound from lightning can be detected when thunderstorms are located more than 200 km from the station. No signal is recorded from lightning flashes occurring between 75 and 200 km away from the station, defining then a silence zone. When the thunderstorm is close to the station, the infrasound signal could reach several Pascal. The signal is then on average 30 dB over the noise level at 1 Hz. Infrasound propagate upward where the highest frequencies are dissipated and can produce a significant heating of the upper mesosphere. Some of these results have been confirmed by case studies with data from the IMS Ivory Coast station. The coverage of the IMS stations is very good to study the thunderstorm activity and its disparity which is a good proxy of the global warming. Progress in data processing for infrasound data in the last ten years and the appearance of global lightning detection network as the World Wide Lightning Localisation Network make such studies possible.

Infrasound from lightning: characteristics and impact on an infrasound station

NASA Astrophysics Data System (ADS)

Farges, T.; Blanc, E.

2009-12-01

More than two third of the infrasound stations of the International Monitoring System (IMS) of the CTBTO are now certified and measure routinely signals due particularly to natural activity (swell, volcano, severe weather including lightning, …). It is well established that more than 2,000 thunderstorms are continuously active all around the world and that about 45 lightning flashes are produced per second over the globe. During the Eurosprite 2005 campaign, we took the opportunity to measure, in France during summer, infrasound from lightning and from sprites (which are transient luminous events occurring over thunderstorm). We examine the possibility to measure infrasound from lightning when thunderstorms are close or far from the infrasound station. Main results concern detection range of infrasound from lightning, amplitude vs. distance law, and characteristics of frequency spectrum. We show clearly that infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. In good noise conditions, infrasound from lightning can be detected when thunderstorms are located more than 200 km from the station. No signal is recorded from lightning flashes occurring between 75 and 200 km away from the station, defining then a silence zone. When the thunderstorm is close to the station, the infrasound signal could reach several Pascal. The signal is then on average 30 dB over the noise level at 1 Hz. Infrasound propagate upward where the highest frequencies are dissipated and can produce a significant heating of the upper mesosphere. Some of these results have been confirmed by case studies with data from the IMS Ivory Coast station. The coverage of the IMS stations is very good to study the thunderstorm activity and its disparity which is a good proxy of the global warming. Progress in data processing for infrasound data in the last ten years and the appearance of global lightning detection network as the World Wide Lightning Localisation Network make such studies possible.

International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station.

PubMed

Eslinger, Paul W; Bowyer, Ted W; Achim, Pascal; Chai, Tianfeng; Deconninck, Benoit; Freeman, Katie; Generoso, Sylvia; Hayes, Philip; Heidmann, Verena; Hoffman, Ian; Kijima, Yuichi; Krysta, Monika; Malo, Alain; Maurer, Christian; Ngan, Fantine; Robins, Peter; Ross, J Ole; Saunier, Olivier; Schlosser, Clemens; Schöppner, Michael; Schrom, Brian T; Seibert, Petra; Stein, Ariel F; Ungar, Kurt; Yi, Jing

2016-06-01

The International Monitoring System (IMS) is part of the verification regime for the Comprehensive Nuclear-Test-Ban-Treaty Organization (CTBTO). At entry-into-force, half of the 80 radionuclide stations will be able to measure concentrations of several radioactive xenon isotopes produced in nuclear explosions, and then the full network may be populated with xenon monitoring afterward. An understanding of natural and man-made radionuclide backgrounds can be used in accordance with the provisions of the treaty (such as event screening criteria in Annex 2 to the Protocol of the Treaty) for the effective implementation of the verification regime. Fission-based production of (99)Mo for medical purposes also generates nuisance radioxenon isotopes that are usually vented to the atmosphere. One of the ways to account for the effect emissions from medical isotope production has on radionuclide samples from the IMS is to use stack monitoring data, if they are available, and atmospheric transport modeling. Recently, individuals from seven nations participated in a challenge exercise that used atmospheric transport modeling to predict the time-history of (133)Xe concentration measurements at the IMS radionuclide station in Germany using stack monitoring data from a medical isotope production facility in Belgium. Participants received only stack monitoring data and used the atmospheric transport model and meteorological data of their choice. Some of the models predicted the highest measured concentrations quite well. A model comparison rank and ensemble analysis suggests that combining multiple models may provide more accurate predicted concentrations than any single model. None of the submissions based only on the stack monitoring data predicted the small measured concentrations very well. Modeling of sources by other nuclear facilities with smaller releases than medical isotope production facilities may be important in understanding how to discriminate those releases from releases from a nuclear explosion. Published by Elsevier Ltd.

Analysis of the Seismic Events Apparently Associated with the 3 September 2017 DPRK Declared Nuclear Explosion

NASA Astrophysics Data System (ADS)

Walter, W. R.; Dodge, D. A.; Ichinose, G.; Myers, S. C.; Ford, S. R.; Pitarka, A.; Pyle, M. L.; Pasyanos, M.; Matzel, E.; Rodgers, A. J.; Mellors, R. J.; Hauk, T. F.; Kroll, K.

2017-12-01

On September 3, 2017, an mb 6.3 seismic event was reported by the USGS in the vicinity of the DPRK nuclear test site at Punggye-ri. Shortly afterwards DPRK declared it had conducted a nuclear explosion. The seismic signals indicate this event is roughly an order of magnitude larger than the largest of the previous five DPRK declared nuclear tests. In addition to its size, this explosion was different from previous DPRK tests in being associated with a number of additional seismic events. Approximately eight and a half minutes after the explosion a seismic event reported as ML 4.0 by the USGS occurred. Regional waveform modeling indicated this event had a collapse mechanism (e.g. Ichinose et al., 2017, written communication). On September 23 and again on October 12, 2017, seismic events were reported near the DPRK test site by the USGS and the CTBTO (on 9/23/17 two events: USGS ML 3.6 and USGS ML 2.6; and on 10/12/17 one event: USGS mb(Lg) 2.9). Aftershocks following underground nuclear testing are expected, though at much lower magnitudes and rates than for comparably sized earthquakes. This difference in aftershock production has been proposed by Ford and Walter (2010), and others as a potential source-type discriminant. Seismic signals from the collapse of cavities formed by underground nuclear testing have also been previously observed. For example, the mb 5.7 nuclear test ATRISCO in Nevada in 1982 was followed twenty minutes later by a collapse with an mb of 4.0. Here we examine the seismic characteristics of nuclear tests, post-test collapses and post-test aftershocks from both the former Nevada test site and the DPRK test site to better understand the differences between these different source-type signals. In particular we look at discriminants such as P/S ratios, to see if there are unique characteristics to post-test collapses and aftershocks. Finally, we apply correlation methods to continuous data at regional stations to look for additional seismic signals that might have an apparent association with the DPRK nuclear testing, post-testing collapses and post-test induced seismicity.

Automatic recovery of aftershock sequences at the International Data Centre: from concept to pipeline

NASA Astrophysics Data System (ADS)

Kitov, I.; Bobrov, D.; Rozhkov, M.

2016-12-01

Aftershocks of larger earthquakes represent an important source of information on the distribution and evolution of stresses and deformations in pre-seismic, co-seismic and post-seismic phases. For the International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Organization (CTBTO) largest aftershocks sequences are also a challenge for automatic and interactive processing. The highest rate of events recorded by two and more seismic stations of the International Monitoring System from a relatively small aftershock area may reach hundreds per hour (e.g. Sumatra 2004 and Tohoku 2011). Moreover, there are thousands of reflected/refracted phases per hour with azimuth and slowness within the uncertainty limits of the first P-waves. Misassociation of these later phases, both regular and site specific, as the first P-wave results in creation of numerous wrong event hypotheses in automatic IDC pipeline. In turn, interactive review of such wrong hypotheses is direct waste of analysts' resources. Waveform cross correlation (WCC) is a powerful tool to separate coda phases from actual P-wave arrivals and to fully utilize the repeat character of waveforms generated by events close in space. Array seismic stations of the IMS enhance the performance of the WCC in two important aspects - they reduce detection threshold and effectively suppress arrivals from all sources except master events. An IDC specific aftershock tool has been developed and merged with standard IDC pipeline. The tool includes several procedures: creation of master events consisting of waveform templates at ten and more IMS stations; cross correlation (CC) of real-time waveforms with these templates, association of arrivals detected at CC-traces in event hypotheses; building events matching IDC quality criteria; and resolution of conflicts between events hypotheses created by neighboring master-events. The final cross correlation standard event lists (XSEL) is a start point of interactive analysis. Since global monitoring of underground nuclear tests is based on historical and synthetic data, each aftershock sequence can be tested for the CTBT violation with big earthquakes as an evasion scenario.

A lightweight messaging-based distributed processing and workflow execution framework for real-time and big data analysis

NASA Astrophysics Data System (ADS)

Laban, Shaban; El-Desouky, Aly

2014-05-01

To achieve a rapid, simple and reliable parallel processing of different types of tasks and big data processing on any compute cluster, a lightweight messaging-based distributed applications processing and workflow execution framework model is proposed. The framework is based on Apache ActiveMQ and Simple (or Streaming) Text Oriented Message Protocol (STOMP). ActiveMQ , a popular and powerful open source persistence messaging and integration patterns server with scheduler capabilities, acts as a message broker in the framework. STOMP provides an interoperable wire format that allows framework programs to talk and interact between each other and ActiveMQ easily. In order to efficiently use the message broker a unified message and topic naming pattern is utilized to achieve the required operation. Only three Python programs and simple library, used to unify and simplify the implementation of activeMQ and STOMP protocol, are needed to use the framework. A watchdog program is used to monitor, remove, add, start and stop any machine and/or its different tasks when necessary. For every machine a dedicated one and only one zoo keeper program is used to start different functions or tasks, stompShell program, needed for executing the user required workflow. The stompShell instances are used to execute any workflow jobs based on received message. A well-defined, simple and flexible message structure, based on JavaScript Object Notation (JSON), is used to build any complex workflow systems. Also, JSON format is used in configuration, communication between machines and programs. The framework is platform independent. Although, the framework is built using Python the actual workflow programs or jobs can be implemented by any programming language. The generic framework can be used in small national data centres for processing seismological and radionuclide data received from the International Data Centre (IDC) of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). Also, it is possible to extend the use of the framework in monitoring the IDC pipeline. The detailed design, implementation,conclusion and future work of the proposed framework will be presented.

Is there evidence for an acoustic signal at IMS infrasound stations from the North Korean event of 12 May 2010?

NASA Astrophysics Data System (ADS)

Koch, K.; Pilger, C.

2016-12-01

Over the last two years more and more evidence has been presented that a small seismic event had occurred in North Korea on 12 May 2010. Most recent work has concluded that the event shows earthquake-like features when applying event identification methods based on regional phase amplitude ratios. These findings are in contrast to previous hypotheses and identification studies which claimed that low-yield nuclear testing had been carried out. Some of these studies were based solely on radionuclide and noble gas detections found at International Monitoring System (IMS) stations as well as at national facilities. Turning to another technology, it has been shown in several studies that underground nuclear tests carried out at the Punggye-ri test site in North Korea have produced infrasound signatures at the closest IMS stations I45RU and I30JP and at national infrasound stations in South Korea. In particular this holds for the tests carried out in 2009, 2013 and 2016. For the 2013 test infrasound arrivals have been included in the Reviewed Event Bulletin (REB) issued by the International Data Center of CTBTO. Based on this experience an effort was undertaken to analyze infrasound data from these IMS stations and to search for signals that may be associated to the 12 May 2010 event. While it is not expected to obtain such a signal for an earthquake source at depth, as would not be expected as well for a buried explosion source of rather small magnitude, the analysis of I45RU and I30JP data suggests a very weak arrival as obtained from frequency-wavenumber analysis showing parameters similar to those obtained for the announced tests. If the features found are indeed not artifacts then one could speculate that (1) the event of concern may not be an earthquake, even though it exhibits seismic signal characteristics causing it to be classified as an earthquake, or (2) the detections may be related to incidental blasting activity in nearby quarries. Propagation modeling of infrasound waves is being carried out to investigate the ducting behavior for the signals observed at regional infrasound stations.

Seismic resonances of acoustic cavities

NASA Astrophysics Data System (ADS)

Schneider, F. M.; Esterhazy, S.; Perugia, I.; Bokelmann, G.

2016-12-01

The goal of an On-Site Inspection (OSI) is to clarify at a possible testsite whether a member state of the Comprehensive nuclear Test Ban Treaty (CTBT)has violated its rules by conducting a underground nuclear test. Compared toatmospheric and underwater tests underground nuclear explosions are the mostdifficult to detect.One primary structural target for the field team during an OSI is the detectionof an underground cavity, created by underground nuclear explosions. Theapplication of seismic-resonances of the cavity for its detection has beenproposed in the CTBT by mentioning "resonance seismometry" as possibletechnique during OSIs. We modeled the interaction of a seismic wave-field withan underground cavity by a sphere filled with an acoustic medium surrounded byan elastic full space. For this setting the solution of the seismic wave-fieldcan be computed analytically. Using this approach the appearance of acousticresonances can be predicted in the theoretical calculations. Resonance peaksappear in the spectrum derived for the elastic domain surrounding the acousticcavity, which scale in width with the density of the acoustic medium. For lowdensities in the acoustic medium as for an gas-filled cavity, the spectralpeaks become very narrow and therefore hard to resolve. The resonancefrequencies, however can be correlated to the discrete set of eigenmodes of theacoustic cavity and can thus be predicted if the dimension of the cavity isknown. Origin of the resonance peaks are internal reverberations of wavescoupling in the acoustic domain and causing an echoing signal that couples outto the elastic domain again. In the gas-filled case the amplitudes in timedomain are very low.Beside theoretical considerations we seek to find real data examples fromsimilar settings. As example we analyze a 3D active seismic data set fromFelsőpetény, Hungary that has been conducted between 2012 and 2014 on behalf ofthe CTBTO. In the subsurface of this area a former clay mine is situated, whichis connected to a karst cave of 30 m diameter in 70 m depth. Our aim is toinvestigate whether resonances predicted from theoretical models can be alsoobserved in data from such real experiments. Observation of spectral resonantpeaks could serve as the foundation of a cavity detection method that could beutilized for nuclear verification.

Understanding the seismic wave propagation inside and around an underground cavity from a 3D numerical survey

NASA Astrophysics Data System (ADS)

Esterhazy, Sofi; Schneider, Felix; Perugia, Ilaria; Bokelmann, Götz

2017-04-01

Motivated by the need to detect an underground cavity within the procedure of an On-Site-Inspection (OSI) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), which might be caused by a nuclear explosion/weapon testing, we aim to provide a basic numerical study of the wave propagation around and inside such an underground cavity. One method to investigate the geophysical properties of an underground cavity allowed by the Comprehensive Nuclear-test Ban Treaty is referred to as "resonance seismometry" - a resonance method that uses passive or active seismic techniques, relying on seismic cavity vibrations. This method is in fact not yet entirely determined by the Treaty and so far, there are only very few experimental examples that have been suitably documented to build a proper scientific groundwork. This motivates to investigate this problem on a purely numerical level and to simulate these events based on recent advances in numerical modeling of wave propagation problems. Our numerical study includes the full elastic wave field in three dimensions. We consider the effects from an incoming plane wave as well as point source located in the surrounding of the cavity at the surface. While the former can be considered as passive source like a tele-seismic earthquake, the latter represents a man-made explosion or a viborseis as used for/in active seismic techniques. Further we want to demonstrate the specific characteristics of the scattered wave field from a P-waves and S-wave separately. For our simulations in 3D we use the discontinuous Galerkin Spectral Element Code SPEED developed by MOX (The Laboratory for Modeling and Scientific Computing, Department of Mathematics) and DICA (Department of Civil and Environmental Engineering) at the Politecnico di Milano. The computations are carried out on the Vienna Scientific Cluster (VSC). The accurate numerical modeling can facilitate the development of proper analysis techniques to detect the remnants of an underground nuclear test, help to set a rigorous scientific base of OSI and contribute to bringing the Treaty into force.

Big Data Solution for CTBT Monitoring Using Global Cross Correlation

NASA Astrophysics Data System (ADS)

Gaillard, P.; Bobrov, D.; Dupont, A.; Grenouille, A.; Kitov, I. O.; Rozhkov, M.

2014-12-01

Due to the mismatch between data volume and the performance of the Information Technology infrastructure used in seismic data centers, it becomes more and more difficult to process all the data with traditional applications in a reasonable elapsed time. To fulfill their missions, the International Data Centre of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO/IDC) and the Département Analyse Surveillance Environnement of Commissariat à l'Energie atomique et aux énergies alternatives (CEA/DASE) collect, process and produce complex data sets whose volume is growing exponentially. In the medium term, computer architectures, data management systems and application algorithms will require fundamental changes to meet the needs. This problem is well known and identified as a "Big Data" challenge. To tackle this major task, the CEA/DASE takes part during two years to the "DataScale" project. Started in September 2013, DataScale gathers a large set of partners (research laboratories, SMEs and big companies). The common objective is to design efficient solutions using the synergy between Big Data solutions and the High Performance Computing (HPC). The project will evaluate the relevance of these technological solutions by implementing a demonstrator for seismic event detections thanks to massive waveform correlations. The IDC has developed an expertise on such techniques leading to an algorithm called "Master Event" and provides a high-quality dataset for an extensive cross correlation study. The objective of the project is to enhance the Master Event algorithm and to reanalyze 10 years of waveform data from the International Monitoring System (IMS) network thanks to a dedicated HPC infrastructure operated by the "Centre de Calcul Recherche et Technologie" at the CEA of Bruyères-le-Châtel. The dataset used for the demonstrator includes more than 300,000 seismic events, tens of millions of raw detections and more than 30 terabytes of continuous seismic data from the primary IMS stations. In this talk, we will present the Master Event algorithm and the associated workflow, we will give an overview of the designed technical solutions (from the building blocks to the global infrastructure), and we will show the preliminary results at a regional scale.

Big Data solution for CTBT monitoring: CEA-IDC joint global cross correlation project

NASA Astrophysics Data System (ADS)

Bobrov, Dmitry; Bell, Randy; Brachet, Nicolas; Gaillard, Pierre; Kitov, Ivan; Rozhkov, Mikhail

2014-05-01

Waveform cross-correlation when applied to historical datasets of seismic records provides dramatic improvements in detection, location, and magnitude estimation of natural and manmade seismic events. With correlation techniques, the amplitude threshold of signal detection can be reduced globally by a factor of 2 to 3 relative to currently standard beamforming and STA/LTA detector. The gain in sensitivity corresponds to a body wave magnitude reduction by 0.3 to 0.4 units and doubles the number of events meeting high quality requirements (e.g. detected by three and more seismic stations of the International Monitoring System (IMS). This gain is crucial for seismic monitoring under the Comprehensive Nuclear-Test-Ban Treaty. The International Data Centre (IDC) dataset includes more than 450,000 seismic events, tens of millions of raw detections and continuous seismic data from the primary IMS stations since 2000. This high-quality dataset is a natural candidate for an extensive cross correlation study and the basis of further enhancements in monitoring capabilities. Without this historical dataset recorded by the permanent IMS Seismic Network any improvements would not be feasible. However, due to the mismatch between the volume of data and the performance of the standard Information Technology infrastructure, it becomes impossible to process all the data within tolerable elapsed time. To tackle this problem known as "BigData", the CEA/DASE is part of the French project "DataScale". One objective is to reanalyze 10 years of waveform data from the IMS network with the cross-correlation technique thanks to a dedicated High Performance Computer (HPC) infrastructure operated by the Centre de Calcul Recherche et Technologie (CCRT) at the CEA of Bruyères-le-Châtel. Within 2 years we are planning to enhance detection and phase association algorithms (also using machine learning and automatic classification) and process about 30 terabytes of data provided by the IDC to update the world seismicity map. From the new events and those in the IDC Reviewed Event Bulletin, we will automatically create various sets of master event templates that will be used for the event location globally by the CTBTO and CEA.

50 years of Global Seismic Observations

NASA Astrophysics Data System (ADS)

Anderson, K. R.; Butler, R.; Berger, J.; Davis, P.; Derr, J.; Gee, L.; Hutt, C. R.; Leith, W. S.; Park, J. J.

2007-12-01

Seismological recordings have been made on Earth for hundreds of years in some form or another, however, global monitoring of earthquakes only began in the 1890's when John Milne created 40 seismic observatories to measure the waves from these events. Shortly after the International Geophysical Year (IGY), a concerted effort was made to establish and maintain a more modern standardized seismic network on the global scale. In the early 1960's, the World-Wide Standardized Seismograph Network (WWSSN) was established through funding from the Advanced Research Projects Agency (ARPA) and was installed and maintained by the USGS's Albuquerque Seismological Laboratory (then a part of the US Coast and Geodetic Survey). This network of identical seismic instruments consisted of 120 stations in 60 countries. Although the network was motivated by nuclear test monitoring, the WWSSN facilitated numerous advances in observational seismology. From the IGY to the present, the network has been upgraded (High-Gain Long-Period Seismograph Network, Seismic Research Observatories, Digital WWSSN, Global Telemetered Seismograph Network, etc.) and expanded (International Deployment of Accelerometers, US National Seismic Network, China Digital Seismograph Network, Joint Seismic Project, etc.), bringing the modern day Global Seismographic Network (GSN) to a current state of approximately 150 stations. The GSN consists of state-of-the-art very broadband seismic transducers, continuous power and communications, and ancillary sensors including geodetic, geomagnetic, microbarographic, meteorological and other related instrumentation. Beyond the GSN, the system of global network observatories includes contributions from other international partners (e.g., GEOSCOPE, GEOFON, MEDNET, F-Net, CTBTO), forming an even larger backbone of permanent seismological observatories as a part of the International Federation of Digital Seismograph Networks. 50 years of seismic network operations have provided valuable data for earth science research. Developments in communications and other technological advances have expanded the role of the GSN in rapid earthquake analysis, tsunami warning, and nuclear test monitoring. With such long-term observations, scientists are now getting a glimpse of Earth structure changes on human time scales, such as the rotation of the inner core, as well as views into climate processes. Continued observations for the next 50 years will enhance our image of the Earth and its processes.

International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eslinger, Paul W.; Bowyer, Ted W.; Achim, Pascal

Abstract The International Monitoring System (IMS) is part of the verification regime for the Comprehensive Nuclear-Test-Ban-Treaty Organization (CTBTO). At entry-into-force, half of the 80 radionuclide stations will be able to measure concentrations of several radioactive xenon isotopes produced in nuclear explosions, and then the full network may be populated with xenon monitoring afterward (Bowyer et al., 2013). Fission-based production of 99Mo for medical purposes also releases radioxenon isotopes to the atmosphere (Saey, 2009). One of the ways to mitigate the effect of emissions from medical isotope production is the use of stack monitoring data, if it were available, so thatmore » the effect of radioactive xenon emissions could be subtracted from the effect from a presumed nuclear explosion, when detected at an IMS station location. To date, no studies have addressed the impacts the time resolution or data accuracy of stack monitoring data have on predicted concentrations at an IMS station location. Recently, participants from seven nations used atmospheric transport modeling to predict the time-history of 133Xe concentration measurements at an IMS station in Germany using stack monitoring data from a medical isotope production facility in Belgium. Participants received only stack monitoring data and used the atmospheric transport model and meteorological data of their choice. Some of the models predicted the highest measured concentrations quite well (a high composite statistical model comparison rank or a small mean square error with the measured values). The results suggest release data on a 15 min time spacing is best. The model comparison rank and ensemble analysis suggests that combining multiple models may provide more accurate predicted concentrations than any single model. Further research is needed to identify optimal methods for selecting ensemble members and those methods may depend on the specific transport problem. None of the submissions based only on the stack monitoring data predicted the small measured concentrations very well. The one submission that best predicted small concentrations also included releases from nuclear power plants. Modeling of sources by other nuclear facilities with smaller releases than medical isotope production facilities may be important in discriminating those releases from releases from a nuclear explosion.« less

Improved scheme for parametrization of convection in the Met Office's Numerical Atmospheric-dispersion Modelling Environment (NAME)

NASA Astrophysics Data System (ADS)

Meneguz, Elena; Thomson, David; Witham, Claire; Kusmierczyk-Michulec, Jolanta

2015-04-01

NAME is a Lagrangian atmospheric dispersion model used by the Met Office to predict the dispersion of both natural and man-made contaminants in the atmosphere, e.g. volcanic ash, radioactive particles and chemical species. Atmospheric convection is responsible for transport and mixing of air resulting in a large exchange of heat and energy above the boundary layer. Although convection can transport material through the whole troposphere, convective clouds have a small horizontal length scale (of the order of few kilometres). Therefore, for large-scale transport the horizontal scale on which the convection exists is below the global NWP resolution used as input to NAME and convection must be parametrized. Prior to the work presented here, the enhanced vertical mixing generated by non-resolved convection was reproduced by randomly redistributing Lagrangian particles between the cloud base and cloud top with probability equal to 1/25th of the NWP predicted convective cloud fraction. Such a scheme is essentially diffusive and it does not make optimal use of all the information provided by the driving meteorological model. To make up for these shortcomings and make the parametrization more physically based, the convection scheme has been recently revised. The resulting version, presented in this paper, is now based on the balance equation between upward, entrainment and detrainment fluxes. In particular, upward mass fluxes are calculated with empirical formulas derived from Cloud Resolving Models and using the NWP convective precipitation diagnostic as closure. The fluxes are used to estimate how many particles entrain, move upward and detrain. Lastly, the scheme is completed by applying a compensating subsidence flux. The performance of the updated convection scheme is benchmarked against available observational data of passive tracers. In particular, radioxenon is a noble gas that can undergo significant long range transport: this study makes use of observations of the isotope 133Xe available at International Monitoring System stations around the South Pacific Ocean. In addition, timeseries of modelled output concentrations obtained using NAME on a grid of 25 km size are compared with those obtained with FLEXPART, another well-known atmospheric dispersion model used by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) and other scientific communities. Findings are discussed and discrepancies investigated.

Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

NASA Astrophysics Data System (ADS)

Annewandter, Robert

2014-05-01

The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced gas transport and subsequent soil gas sampling during On-Site inspections. Generally, gas transport has been widely studied with different numerical codes. However, gas transport of radioxenons and radioiodines in the post-detonation regime and their possible fractionation is still neglected in the open peer-reviewed literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the multiple isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radionuclides, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different mass diffusivities due to mass differences between the radionuclides. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures or highly conductive faults which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a so-called ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which is recognized by the oil industry as leading in Discrete Fracture-Matrix (DFM) simulations. It has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations, fracture propagation in fractured, porous media, and Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite volume method. The parabolic and hyperbolic problem can be solved separately by operator-splitting. The resulting system of linear equations is solved by the algebraic multigrid library SAMG, developed at the Fraunhofer Institute for Algorithms and Scientific Computing, Germany. CSMP++ is developed at Montan University of Leoben, ETH Zuerich, Imperial College London and Heriot-Watt University in Edinburgh. This study examines barometric pumping-driven subsurface transport of Xe-135, Xe-133m, Xe-133, Xe-131m including I-131, I-133 and I-135 on arrival times and isotopic activity ratios. This work was funded by the CTBTO Research Award for Young Scientist and Engineers (2013).

Testing the Reviewed Event Bulletin of the International Data Centre Using Waveform Cross Correlation: Repeat Events at Aitik Copper Mine, Sweden

NASA Astrophysics Data System (ADS)

Kitov, I. O.; Rozhkov, N.; Bobrov, D.; Rozhkov, M.; Yedlin, M. J.

2016-12-01

The quality of the Reviewed Event Bulletin (REB) issued by the International Data Centre (IDC) of the Comprehensive Nuclear-Test- Ban Treaty Organization (CTBTO) is crucial for the Member States as well as for the seismological community. One of the most efficient methods to test the REB quality is using repeat events having very accurate absolute locations. Hundreds of quarry blasts detonated at Aitik copper mine (the central point of active mining - 67.08N, 20.95E) were recorded by several seismic arrays of the International Monitoring System (IMS), found by IDC automatic processing and then confirmed by analysts as REB events. The size of the quarry is approximately 1 km and one can consider that the uncertainty in absolute coordinates of the studied events is less than 0.5 km as measured from the central point. In the REB, the corresponding epicenters are almost uniformly scattered over the territory 67.0N to 67.3N, and 20.7E to 21.5E. These REB locations are based on the measured arrival times as well as azimuth and slowness estimates at several IMS stations with the main input from ARCES, NOA, FINES, and HFS. The higher scattering of REB locations is caused by the uncertainty in measurements and velocity model. Seismological methods based on waveform cross correlation allow very accurate relative location of repeat events. Here we test the level of similarity between signals from these events. It was found that IMS primary array station ARCES demonstrates the highest similarity as expressed by cross correlation coefficient (CC) and signal-to-noise ratio (SNR) calculated at the CC traces. Small-aperture array FINES is the second best and large-aperture array NOA demonstrating mediocre performance likely due its size and the loss of coherency between high-frequency and relatively low-velocity signals from the mine. During the last five years station ARCES has been upgraded from a vertical array to a 3-C one. This transformation has improved the performance of CC-technique as applied to the Aitik mine events. We have also applied a Principal Component Analysis to estimate the level of variability in the signals as well as to build the best waveform template for effective detection and identification of all blasts conducted at Aitik mine.

Using waveform cross correlation for automatic recovery of aftershock sequences

NASA Astrophysics Data System (ADS)

Bobrov, Dmitry; Kitov, Ivan; Rozhkov, Mikhail

2017-04-01

Aftershock sequences of the largest earthquakes are difficult to recover. There can be several hundred mid-sized aftershocks per hour within a few hundred km from each other recorded by the same stations. Moreover, these events generate thousands of reflected/refracted phases having azimuth and slowness close to those from the P-waves. Therefore, aftershock sequences with thousands of events represent a major challenge for automatic and interactive processing at the International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Organization (CTBTO). Standard methods of detection and phase association do not use all information contained in signals. As a result, wrong association of the first and later phases, both regular and site specific, produces enormous number of wrong event hypotheses and destroys valid event hypotheses in automatic IDC processing. In turn, the IDC analysts have to reject false and recreate valid hypotheses wasting precious human resources. At the current level of the IDC catalogue completeness, the method of waveform cross correlation (WCC) can resolve most of detection and association problems fully utilizing the similarity of waveforms generated by aftershocks. Array seismic stations of the International monitoring system (IMS) can enhance the performance of the WCC method: reduce station-specific detection thresholds, allow accurate estimate of signal attributes, including relative magnitude, and effectively suppress irrelevant arrivals. We have developed and tested a prototype of an aftershock tool matching all IDC processing requirements and merged it with the current IDC pipeline. This tool includes creation of master events consisting of real or synthetic waveform templates at ten and more IMS stations; cross correlation (CC) of real-time waveforms with these templates, association of arrivals detected at CC-traces in event hypotheses; building events matching the IDC quality criteria; and resolution of conflicts between events hypotheses created by neighboring master-events. The final cross correlation standard event lists (XSEL) is a start point for interactive analysis with standard tools. We present select results for the biggest earthquakes, like Sumatra 2004 and Tohoku 2011, as well as for several smaller events with hundreds of aftershocks. The sensitivity and resolution of the aftershock tool is demonstrated on the example of mb=2.2 aftershock found after the September 9, 2016 DPRK test.

Natural and anthropogenic ocean noise recorded at long-term and temporary observatories

NASA Astrophysics Data System (ADS)

Grevemeyer, Ingo; Metz, Dirk; Watts, Anthony B.; Geissler, Wolfram

2017-04-01

Most people worldwide would assume that the oceans are silent. However, a number of natural phenomenon's like ocean waves, wind, lightening, ice noise, earthquakes, and submarine volcanic activity contributes to the ambient ocean noise. During their evolution, marine animals like fish and mammals have adopted in many ways to the acoustic properties of the sea. Yet in recent decades, anthropogenic and hence manmade ocean noise level has risen profoundly. Due to extreme reliance of fish and mammals on underwater sounds for basic life functions, including searching for food or mate and the absence of any mechanism to safeguard them against it, underwater noise pollution may disrupt marine life. The primary sources of low-frequency anthropogenic noise include sounds associated with shipping, military operations, oil and gas exploration and production, and even research activities. Some scientists suggest that today virtually no marine environment is without any noise pollution. Thus, all marine life forms that rely heavily on the integrity of their acoustic habitat may have to adapt to new conditions. Of greatest concern for whales are low-frequency sounds that travel long distances in the ocean. Ship propellers and motors, for instance, produce sound at low frequencies, as do natural and manmade seismic activity. These profound, loud noises reverberate in the deep ocean and can effectively mask or block vital whale communication. However, in general very little is known about the world-wide distribution of ambient ocean noise. Thus, on a global scale and considering the vast areas of the world's oceans, we know virtually nothing about noise levels in different parts of the oceans and how anthropogenic noise contributes to ambient noise. Here, we use hydrophone recordings from the UN's Comprehensive Nuclear-Test-Ban Treaty organization (CTBTO) and ocean-bottom seismometers to provide an assessment of noise in all major basins, including the Pacific, Atlantic and Indian Ocean at low frequencies of <50 Hz. Hydrophones recorded explosive volcanic eruptions, calls of Fin whales, distant seismic surveys and ship's traffic. Silent setting are characterized at 10 to 50 Hz by a noise level of 50 to 70 dB while areas affected by heavy shipping show noise levels of >100 dB. At frequencies below 1 Hz the ambient noise field is dominated by microseisms, forces by ocean gravity waves and surf.

Three-dimensional parabolic equation models of the acoustic coverage of the CTBT hydrophone station at Crozet

NASA Astrophysics Data System (ADS)

Zampolli, Mario; Haralabus, Georgios; Prior, Mark K.; Heaney, Kevin D.; Campbell, Richard

2014-05-01

Hydrophone stations of the Comprehensive Nuclear-Test-Ban Organisation (CTBTO) International Monitoring System (IMS), with the exception of one in Australia, comprise two triplets of submerged moored hydrophones, one North and one South of the island from which the respective system is deployed. Triplet distances vary approximately between 50 - 100 km from the island, with each triplet connected to the receiving shore equipment by fibre-optic submarine data cables. Once deployed, the systems relay underwater acoustic waveforms in the band 1 - 100 Hz in real time to Vienna via a shore based satellite link. The design life of hydroacoustic stations is at least 20 years, without need for any maintenance of the underwater system. The re-establishment of hydrophone monitoring station HA04 at Crozet (French Southern and Antarctic Territories) in the South-Western Indian Ocean is currently being investigated. In order to determine appropriate locations and depths for the installation of the hydrophones a number of constraints need to be taken into account and balanced against each other. The most important of these are (i) hydrophone depth in a region where the sound-speed profile is mostly upward refracting and the Sound Fixing and Ranging (SOFAR) channel is not well defined, (ii) a safe distance from the surface currents which occupy the first few hundred meters of the water column, (iii) seabed slopes that enable the safe deployment of the hydrophone mooring bases, (iv) avoidance of regions of high internal tide activity, (v) choice of locations to optimize basin and cross-basin scale acoustic coverage of each triplet and (vi) redundancy considerations so that one triplet can partially cover for the other one in case of necessity. A state-of-the-art three-dimensional (3-D) parabolic equation acoustic propagation model was used to model the propagation for a number of potential triplet locations. Criteria for short-listing candidate triplet locations were based on acoustic coverage towards the North and South, as well as overall acoustic coverage, taking into account different scales of source strength. An increase in the predicted area coverage compared to predictions based on 2-D modelling was observed and attributed to diffraction around sharp localized features such as islands or sea-mounts.

Seismological Investigations of the National Data Centre Preparedness Exercise 2015 (NPE2015)

NASA Astrophysics Data System (ADS)

Gestermann, Nicolai; Hartmann, Gernot; Ross, Jens-Ole

2017-04-01

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) prohibits all kinds of nuclear explosions. For the detection of treaty violations the International Monitoring System (IMS) operates stations observing seismic, hydroacoustic, and infrasound signals as well as radioisotopes in the atmosphere. While the IMS data is collected, processed and technically analyzed in the International Data Center (IDC) of the CTBT-Organization, National Data Centers (NDC) provide interpretation and advice to their government concerning suspicious detections occurring in IMS data. The National Data Centre Preparedness Exercises (NPE) are regularly performed dealing with fictitious treaty violations to practice the combined analysis of CTBT verification technologies and national technical means. These exercises should help to evaluate the effectiveness of analysis procedures applied at NDCs and the quality, completeness and usefulness of IDC products. The NPE2015 is a combined radionuclide-waveform scenario. Fictitious particulate radionuclide and radioxenon measurements at stations of the IMS (International Monitoring System) of the CTBTO were reported to the international community. The type of isotopes and concentrations could arise from an underground nuclear explosion (UNE). The task of the exercise is to identify the scenario behind the provided data. The source region and time domain of a possible treaty violation activity was determined from ATM in backtracking mode with input data from the fictitious data. A time slot in October and a region around the mining area of Lubin could be identified as the possible source area of the fictitious measurements. The seismicity of the determined source region was investigated in detail to identify events which cannot be classified as natural or induced within the relevant time interval. The comparison of spectral characteristics and a cluster analysis was applied to search for a non-characteristic event within a number of known induced events in the area. The results reveal that none of the candidate events had an explosion like characteristic. All candidate events are part of event cluster with a minimum of seven events with comparable signature. The possibility of a treaty violation would be very low in a real scenario. If the nature of a suspicious event cannot be clarified with data of the IMS or national technical means, an on-site inspection (OSI) can be requested by the member states. Taking into account the results of the seismological investigations it could be decided that an OSI is not necessary for the possible source region to exclude the possibility of a fictitious clandestine underground nuclear explosion.

The GEOSCOPE program: state of the art in 2005

NASA Astrophysics Data System (ADS)

Roult, G.; Lepine, J.; Bonaime, S.; Riveira, L.; Geoscope Group, T.

2005-12-01

The GEOSCOPE program was launched in 1982 by the National Institute of Sciences of Universe (INSU), a department of the French National Center of Scientific Research (CNRS), at the instigation of the Institute of Physics of the Earth of Paris (IPGP). The purpose was the installation of about 25 stations well distributed worldwide (in particular in the southern hemisphere), in the standard configuration defined by the FDSN (very broad-band 24 bit, continuous recording at 20sps). The GEOSCOPE program is operating 28 digital 3-component very- broadband stations. Data from large events are teletransmitted from some stations (by phone RTC line or through internet) and made available within one day. A satellite transmission system is now working, in cooperation with the french military agency CEA/DASE, in cooperation with CTBTO (Dzumac in New Caledonia), and the data are available continuously, with a low gain. We are replacing the old Streckeisen digitizers with new Quanterra type ones, in order to be ready for the next step which will consist in gathering data towards our Data Center in real-time. Presently data from 6 stations arrive at the IPGP Geoscope Data Center in near real-time, with a delay depending on the station. The challenge is to link the maximum number of stations to our Data Center for getting data in real time; that purpose can be reached in few years. We are able to upgrade 3 or 4 stations every year, giving priority to the ones easy to link permanently to Paris. For the last ten years we've been progressively installing microbarometers and thermometers, transforming all our stations in multiparameter observatories. In terms of siting locations, the aim of the GEOSCOPE program is almost fulfilled; we re-installed the chinese station WUS with modern equipment in October 2004, we installed in December 2004 a new station TAOE in Marquesas Islands in cooperation with CEA/DASE, another one COYC in Patagonia (Chile) in December 2004. We plan to install a second station in Russia at high latitude at VOR (Vorkuta). In the framework of cooperation between IRIS and GEOSCOPE we installed in March 2004 a joint station at TRIS (Tristan Da Cunha), and we decided to share our equipment at KIP station that became a joint station. Our purpose is to maintain our stations at original sites (high latitudes) and to fill some geographical gaps in the southern hemisphere.

GT0 Explosion Sources for IMS Infrasound Calibration: Charge Design and Yield Estimation from Near-source Observations

NASA Astrophysics Data System (ADS)

Gitterman, Y.; Hofstetter, R.

2014-03-01

Three large-scale on-surface explosions were conducted by the Geophysical Institute of Israel (GII) at the Sayarim Military Range, Negev desert, Israel: about 82 tons of strong high explosives in August 2009, and two explosions of about 10 and 100 tons of ANFO explosives in January 2011. It was a collaborative effort between Israel, CTBTO, USA and several European countries, with the main goal to provide fully controlled ground truth (GT0) infrasound sources, monitored by extensive observations, for calibration of International Monitoring System (IMS) infrasound stations in Europe, Middle East and Asia. In all shots, the explosives were assembled like a pyramid/hemisphere on dry desert alluvium, with a complicated explosion design, different from the ideal homogenous hemisphere used in similar experiments in the past. Strong boosters and an upward charge detonation scheme were applied to provide more energy radiated to the atmosphere. Under these conditions the evaluation of the actual explosion yield, an important source parameter, is crucial for the GT0 calibration experiment. Audio-visual, air-shock and acoustic records were utilized for interpretation of observed unique blast effects, and for determination of blast wave parameters suited for yield estimation and the associated relationships. High-pressure gauges were deployed at 100-600 m to record air-blast properties, evaluate the efficiency of the charge design and energy generation, and provide a reliable estimation of the charge yield. The yield estimators, based on empirical scaled relations for well-known basic air-blast parameters—the peak pressure, impulse and positive phase duration, as well as on the crater dimensions and seismic magnitudes, were analyzed. A novel empirical scaled relationship for the little-known secondary shock delay was developed, consistent for broad ranges of ANFO charges and distances, which facilitates using this stable and reliable air-blast parameter as a new potential yield estimator. The delay data of the 2009 shot with IMI explosives, characterized by much higher detonation velocity, are clearly separated from ANFO data, thus indicating a dependence on explosive type. This unique dual Sayarim explosion experiment (August 2009/January 2011), with the strongest GT0 sources since the establishment of the IMS network, clearly demonstrated the most favorable westward/eastward infrasound propagation up to 3,400/6,250 km according to appropriate summer/winter weather pattern and stratospheric wind directions, respectively, and thus verified empirically common models of infrasound propagation in the atmosphere.

Seismicity of the North Atlantic as measured by the International Data Centre using waveform cross correlation

NASA Astrophysics Data System (ADS)

Given, J. W.; Bobrov, D.; Kitov, I. O.; Spiliopoulos, S.

2012-12-01

The Technical Secretariat (TS) of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) will carry out the verification of the CTBT which obligates each State Party not to carry out any nuclear explosions, independently of their size and purpose. The International Data Centre (IDC) receives, collects, processes, analyses, reports on and archives data from the International Monitoring System(IMS). The IDC is responsible for automatic and interactive processing of the IMS data and for standard IDC products. The IDC is also required by the Treaty to progressively enhance its technical capabilities. In this study, we use waveform cross correlation as a technique to improve the detection capability and reliability of the seismic part of the IMS. In order to quantitatively estimate the gain obtained by cross correlation on the current sensitivity of automatic and interactive processing we compared seismic bulletins built for the North Atlantic (NA), which is an isolated region with earthquakes concentrating around the Mid-Atlantic Ridge. This avoids the influence of adjacent seismic regions on the final bulletins: the Reviewed Event Bulletin (REB) issued by the International Data Centre and the cross correlation Standard Event List (XSEL). We have cross correlated waveforms from ~1500 events reported in the REB since 2009. The resulting cross correlation matrix revealed the best candidates for master events. High-quality signals (SNR>5.0) recorded at eighteen array stations from approximately 50 master events evenly distributed over the seismically active zone in the NA were selected as templates. These templates are used for a continuous calculation of cross correlation coefficients since 2011. All detections obtained by cross-correlation are then used to build events according to the current IDC definition, i.e. at least three primary stations with accurate arrival times, azimuth and slowness estimates. The qualified event hypotheses populated the XSEL. In order to confirm the XSEL events not found in the REB, a portion of the newly built events was reviewed interactively by experienced analysts. The influence of all defining parameters (cross correlation coefficient threshold and SNR, F-statistics and fk-analysis, azimuth and slowness estimates, relative magnitude, etc.) on the final XSEL has been studied using the relevant frequency distributions for all detections vs only for those which were associated with the XSEL events. These distributions are also station and master dependent. This allows estimating the thresholds for all defining parameters, which may be adjusted to balance the rate of missed events and false alarms.

Infrasound from lightning measured in Ivory Coast from 2004 to 2014

NASA Astrophysics Data System (ADS)

Farges, Thomas; Le Pichon, Alexis; Ceranna, Lars; Diawara, Adama

2016-04-01

It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. 80 % of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes …). Some of the IMS stations are located where lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. Assink et al. (2008) and Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within 300 km. One-to-one correlation is possible when the thunderstorm is within about 75 km from the station. When the lightning flash occurs within 20 km, it is also possible to rebuild the 3D geometry of the discharges when the network size is less than 100 m (Arechiga et al., 2011; Gallin, 2014). An IMS infrasound station has been installed in Ivory Coast since 2002. The lightning rate of this region is 10-20 flashes/km²/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 10 years of data (2005-2014). Correlation between infrasound having a mean frequency higher than 1 Hz and lightning flashes detected by the World Wide Lightning Location Network (WWLLN) is systematically looked for. One-to-one correlation is obtained for flashes occurring within about 100 km. An exponential decrease of the infrasound amplitude with the distance of one order of magnitude per 50 km is found. The detection variability with the arrival azimuth is examined. A non-negligible number of events coming from the shadow zone (30 - 200 km) is found. It is also interesting to note that most of the infrasound related to lightning flashes is due to thunderstorm which occurred more than 200 km away from the station. However, it is hard to deduce any precise characteristics in those cases.

Acoustic-Seismic Coupling of Broadband Signals - Analysis of Potential Disturbances during CTBT On-Site Inspection Measurements

NASA Astrophysics Data System (ADS)

Liebsch, Mattes; Altmann, Jürgen

2015-04-01

For the verification of the Comprehensive Nuclear Test Ban Treaty (CTBT) the precise localisation of possible underground nuclear explosion sites is important. During an on-site inspection (OSI) sensitive seismic measurements of aftershocks can be performed, which, however, can be disturbed by other signals. To improve the quality and effectiveness of these measurements it is essential to understand those disturbances so that they can be reduced or prevented. In our work we focus on disturbing signals caused by airborne sources: When the sound of aircraft (as often used by the inspectors themselves) hits the ground, it propagates through pores in the soil. Its energy is transferred to the ground and soil vibrations are created which can mask weak aftershock signals. The understanding of the coupling of acoustic waves to the ground is still incomplete. However, it is necessary to improve the performance of an OSI, e.g. to address potential consequences for the sensor placement, the helicopter trajectories etc. We present our recent advances in this field. We performed several measurements to record sound pressure and soil velocity produced by various sources, e.g. broadband excitation by jet aircraft passing overhead and signals artificially produced by a speaker. For our experimental set-up microphones were placed close to the ground and geophones were buried in different depths in the soil. Several sensors were shielded from the directly incident acoustic signals by a box coated with acoustic damping material. While sound pressure under the box was strongly reduced, the soil velocity measured under the box was just slightly smaller than outside of it. Thus these soil vibrations were mostly created outside the box and travelled through the soil to the sensors. This information is used to estimate characteristic propagation lengths of the acoustically induced signals in the soil. In the seismic data we observed interference patterns which are likely caused by the superposition of acoustically induced seismic waves with reflections at a layer boundary. Their frequencies of increased/decreased amplitudes depend on the angle of incidence of the acoustic signal. So these patterns can be used to estimate the path(s) of propagation of acoustically induced soil vibrations. The frequency-dependent phase offset between different sensors is used to estimate the propagation velocity of soil. The research aims to deliver a better understanding of the interaction of acoustic waves and the ground when hitting the surface, the transfer of energy from sound waves into the soil and the possible excitation of seismic surface waves. The goal is to develop recommendations for sensitive seismic measurements during CTBTO on-site inspections to reduce disturbing vibrations caused by airborne sources.

Results from a 14-month hydroacoustic monitoring of the three mid-oceanic ridges in the Indian Ocean

NASA Astrophysics Data System (ADS)

Royer, J.-Y.; Dziak, R. P.; Delatre, M.; Chateau, R.; Brachet, C.; Haxel, J. H.; Matsumoto, H.; Goslin, J.; Brandon, V.; Bohnenstielh, D. R.

2009-04-01

From October 2006 to January 2008, an hydroacoustic experiment in the Indian Ocean was carried out by the CNRS/University of Brest and NOAA/Oregon State University to monitor the low-level seismic activity associated with the three contrasting spreading ridges and deforming zones in the Indian Ocean. Three autonomous hydrophones were moored in the SOFAR channel by R/V Marion Dufresne for 14 months in the Madagascar Basin, and northeast and southwest of Amsterdam Island, complementing the two permanent hydroacoustic stations of the Comprehensive nuclear-Test-Ban Treaty Organization (CTBTO) located near Diego Garcia Island and off Cape Leeuwin. The three instruments successfully collected 14 month of continuous acoustic records. Combined with the records from the permanent stations, the array detected 1780 acoustic events consisting mostly of earthquake generated T-waves, but also of iceberg tremors from Wilkes Land, Antarctica. Within the triangle defined by the temporary array, the three ridges exhibit contrasting seismicity patterns. Along the Southeast Indian ridge (SEIR), the 272 acoustic events (vs 24 events in the NEIC catalog) occur predominantly along the transform faults ; only one ridge segment (76˚E) displays a continuous activity for 10 months. Along the Central Indian Ridge (CIR), seismicity is distributed along fracture zones and ridge segments (269 events vs 45 NEIC events), with two clusters of events near the triple junction (24-25S) and south of Marie-Celeste FZ (18.5S). Along the Southwest Indian Ridge (SWIR), the 222 events (vs 31 NEIC events) are distributed along the ridge segments with a larger number of events west of Melville FZ and a cluster at 58E. The immediate vicinity of the Rodrigues triple junction shows periods of quiescence and of intense activity. Some large earthquakes (Mb>5) near the triple junction (SEIR and CIR) seem to be preceded by several acoustic events that may be precursors. Finally, off-ridge seismicity is mostly detected in the southern part of the Central Indian Basin as a result of the intraplate deformation between the Capricorn and Australian plates. Other signals of interest are identified such as a 6-week long series of broadband (1-125 Hz) explosive signals detected only by the instrument located between Kerguelen and Amsterdam islands, many cryogenic tremors easily recognizable from their varying tones and harmonics, some of which can be precisely located off the Antarctic shelf, and finally whale calls attributed to four different whale species. This vocal activity is found to be highly seasonal, occurring mainly from April to October with subspecies variations. Detailed analyses of this unique data set are still underway.

Monitoring of reported sudden emission rate changes of major radioxenon emitters in the northern and southern hemispheres in 2008 to assess their contribution to the respective radioxenon backgrounds

NASA Astrophysics Data System (ADS)

Saey, P. R. J.; Auer, M.; Becker, A.; Colmanet, S.; Hoffmann, E.; Nikkinen, M.; Schlosser, C.; Sonck, M.

2009-04-01

Atmospheric radioxenon monitoring is a key component of the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Radiopharmaceutical production facilities (RPF) have recently been identified of emitting the major part of the environmental radioxenon measured at globally distributed monitoring sites deployed to strengthen the radionuclide part of the CTBT verification regime. Efforts to raise a global radioxenon emission inventory revealed that the global total emission from RPF's is 2-3 orders of magnitude higher than the respective emissions related to maintenance of all nuclear power plants (NPP). Given that situation we have seen in 2008 two peculiar hemisphere-specific situations: 1) In the northern hemisphere, a joint shutdown of the global largest four radiopharmaceutical facilities revealed the contribution of the normally 'masked' NPP related emissions. Due to an incident, the Molybdenum production at the "Institut des Radioéléments" (IRE) in Fleurus, Belgium, was shut down between Monday 25 August and 2 December 2008. IRE is the third largest global producer of medical isotopes. In the same period, but for different reasons, the other three worldwide largest producers (CRL in Canada, HFR in The Netherlands and NTP in South Africa) also had scheduled and unscheduled shutdowns. The activity concentrations of 133Xe measured at the Schauinsland Mountain station near Freiburg in Germany (situated 380 km SW of Fleurus) which have a mean of 4.8 mBq/m3 for the period February 2004 - August 2008, went down to 0.87 mBq/m3 for the period September - November 2008. 2) In the southern hemisphere, after a long break, the only radiopharmaceutical facility in Australia started up test production in late November 2008. In the period before the start-up, the background of radioxenon in Australia (Melbourne and Darwin) was below measurable quantities. During six test runs of the renewed RPF at ANSTO in Lucas Heights, up to 6 mBq/m3 of 133Xe were measured in the station at Melbourne, 700 km SW from the facility. This paper confirms the hypothesis that radiopharmaceutical production facilities are the major emitters of radioxenon first of all. Moreover it demonstrates how the temporal shut down of these facilities indicates the scale of their contribution to the European radioxenon background, which decreased 6 fold. Finally we have studied the contribution of the start-up of a renewed RFP to the buildup of a radioxenon background across Australia and the southern hemisphere. Disclaimer The views expressed in this publication are those of the authors and do not necessarily reflect the views of the CTBTO Preparatory Commission or any of the participating institutions.

The ear, the eye, earthquakes and feature selection: listening to automatically generated seismic bulletins for clues as to the differences between true and false events.

NASA Astrophysics Data System (ADS)

Kuzma, H. A.; Arehart, E.; Louie, J. N.; Witzleben, J. L.

2012-04-01

Listening to the waveforms generated by earthquakes is not new. The recordings of seismometers have been sped up and played to generations of introductory seismology students, published on educational websites and even included in the occasional symphony. The modern twist on earthquakes as music is an interest in using state-of-the-art computer algorithms for seismic data processing and evaluation. Algorithms such as such as Hidden Markov Models, Bayesian Network models and Support Vector Machines have been highly developed for applications in speech recognition, and might also be adapted for automatic seismic data analysis. Over the last three years, the International Data Centre (IDC) of the Comprehensive Test Ban Treaty Organization (CTBTO) has supported an effort to apply computer learning and data mining algorithms to IDC data processing, particularly to the problem of weeding through automatically generated event bulletins to find events which are non-physical and would otherwise have to be eliminated by the hand of highly trained human analysts. Analysts are able to evaluate events, distinguish between phases, pick new phases and build new events by looking at waveforms displayed on a computer screen. Human ears, however, are much better suited to waveform processing than are the eyes. Our hypothesis is that combining an auditory representation of seismic events with visual waveforms would reduce the time it takes to train an analyst and the time they need to evaluate an event. Since it takes almost two years for a person of extraordinary diligence to become a professional analyst and IDC contracts are limited to seven years by Treaty, faster training would significantly improve IDC operations. Furthermore, once a person learns to distinguish between true and false events by ear, various forms of audio compression can be applied to the data. The compression scheme which yields the smallest data set in which relevant signals can still be heard is likely an excellent candidate from which to draw features that can be fed into machine learning algorithms since it contains a compact numerical representation of the information that humans need to evaluate events. The challenge in this work is that, although it is relatively easy to pick out earthquake arrivals in waveform data from a single station, when stations are combined the addition of background noise tends to confuse and overwhelm the listener. To solve this problem, we rely on techniques such as the slowing down of recordings without altering the pitch which are used by ethnomusicologists to understand highly complex rhythms and sounds. We work with professional musicians and recorders to mix the data from different seismic stations in a way which reduces noise and preserves the uniqueness of each station.

Nuclear Test Depth Determination with Synthetic Modelling: Global Analysis from PNEs to DPRK-2016

NASA Astrophysics Data System (ADS)

Rozhkov, Mikhail; Stachnik, Joshua; Baker, Ben; Epiphansky, Alexey; Bobrov, Dmitry

2016-04-01

Seismic event depth determination is critical for the event screening process at the International Data Center, CTBTO. A thorough determination of the event depth can be conducted mostly through additional special analysis because the IDC's Event Definition Criteria is based, in particular, on depth estimation uncertainties. This causes a large number of events in the Reviewed Event Bulletin to have depth constrained to the surface making the depth screening criterion not applicable. Further it may result in a heavier workload to manually distinguish between subsurface and deeper crustal events. Since the shape of the first few seconds of signal of very shallow events is very sensitive to the depth phases, cross correlation between observed and theoretic seismograms can provide a basis for the event depth estimation, and so an expansion to the screening process. We applied this approach mostly to events at teleseismic and partially regional distances. The approach was found efficient for the seismic event screening process, with certain caveats related mostly to poorly defined source and receiver crustal models which can shift the depth estimate. An adjustable teleseismic attenuation model (t*) for synthetics was used since this characteristic is not known for most of the rays we studied. We studied a wide set of historical records of nuclear explosions, including so called Peaceful Nuclear Explosions (PNE) with presumably known depths, and recent DPRK nuclear tests. The teleseismic synthetic approach is based on the stationary phase approximation with hudson96 program, and the regional modelling was done with the generalized ray technique by Vlastislav Cerveny modified to account for the complex source topography. The software prototype is designed to be used for the Expert Technical Analysis at the IDC. With this, the design effectively reuses the NDC-in-a-Box code and can be comfortably utilized by the NDC users. The package uses Geotool as a front-end for data retrieval and pre-processing. After the event database is compiled, the control is passed to the driver software, running the external processing and plotting toolboxes, which controls the final stage and produces the final result. The modules are mostly Python coded, C-coded (Raysynth3D complex topography regional synthetics) and FORTRAN coded synthetics from the CPS330 software package by Robert Herrmann of Saint Louis University. The extension of this single station depth determination method is under development and uses joint information from all stations participating in processing. It is based on simultaneous depth and moment tensor determination for both short and long period seismic phases. A novel approach recently developed for microseismic event location utilizing only phase waveform information was migrated to a global scale. It should provide faster computation as it does not require intensive synthetic modelling, and might benefit processing noisy signals. A consistent depth estimate for all recent nuclear tests was produced for the vast number of IMS stations (primary and auxiliary) used in processing.

RISMA: A Rule-based Interval State Machine Algorithm for Alerts Generation, Performance Analysis and Monitoring Real-Time Data Processing

NASA Astrophysics Data System (ADS)

Laban, Shaban; El-Desouky, Aly

2013-04-01

The monitoring of real-time systems is a challenging and complicated process. So, there is a continuous need to improve the monitoring process through the use of new intelligent techniques and algorithms for detecting exceptions, anomalous behaviours and generating the necessary alerts during the workflow monitoring of such systems. The interval-based or period-based theorems have been discussed, analysed, and used by many researches in Artificial Intelligence (AI), philosophy, and linguistics. As explained by Allen, there are 13 relations between any two intervals. Also, there have also been many studies of interval-based temporal reasoning and logics over the past decades. Interval-based theorems can be used for monitoring real-time interval-based data processing. However, increasing the number of processed intervals makes the implementation of such theorems a complex and time consuming process as the relationships between such intervals are increasing exponentially. To overcome the previous problem, this paper presents a Rule-based Interval State Machine Algorithm (RISMA) for processing, monitoring, and analysing the behaviour of interval-based data, received from real-time sensors. The proposed intelligent algorithm uses the Interval State Machine (ISM) approach to model any number of interval-based data into well-defined states as well as inferring them. An interval-based state transition model and methodology are presented to identify the relationships between the different states of the proposed algorithm. By using such model, the unlimited number of relationships between similar large numbers of intervals can be reduced to only 18 direct relationships using the proposed well-defined states. For testing the proposed algorithm, necessary inference rules and code have been designed and applied to the continuous data received in near real-time from the stations of International Monitoring System (IMS) by the International Data Centre (IDC) of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The CLIPS expert system shell has been used as the main rule engine for implementing the algorithm rules. Python programming language and the module "PyCLIPS" are used for building the necessary code for algorithm implementation. More than 1.7 million intervals constitute the Concise List of Frames (CLF) from 20 different seismic stations have been used for evaluating the proposed algorithm and evaluating stations behaviour and performance. The initial results showed that proposed algorithm can help in better understanding of the operation and performance of those stations. Different important information, such as alerts and some station performance parameters, can be derived from the proposed algorithm. For IMS interval-based data and at any period of time it is possible to analyze station behavior, determine the missing data, generate necessary alerts, and to measure some of station performance attributes. The details of the proposed algorithm, methodology, implementation, experimental results, advantages, and limitations of this research are presented. Finally, future directions and recommendations are discussed.

Technology Foresight and nuclear test verification: a structured and participatory approach

NASA Astrophysics Data System (ADS)

Noack, Patrick; Gaya-Piqué, Luis; Haralabus, Georgios; Auer, Matthias; Jain, Amit; Grenard, Patrick

2013-04-01

As part of its mandate, the CTBTO's nuclear explosion monitoring programme aims to maintain its sustainability, effectiveness and its long-term relevance to the verification regime. As such, the PTS is conducting a Technology Foresight programme of activities to identify technologies, processes, concepts and ideas that may serve said purpose and become applicable within the next 20 years. Through the Technology Foresight activities (online conferences, interviews, surveys, workshops and other) we have involved the wider science community in the fields of seismology, infrasound, hydroacoustics, radionuclide technology, remote sensing and geophysical techniques. We have assembled a catalogue of over 200 items, which incorporate technologies, processes, concepts and ideas which will have direct future relevance to the IMS (International Monitoring System), IDC (International Data Centre) and OSI (On-Site Inspection) activities within the PTS. In order to render this catalogue as applicable and useful as possible for strategy and planning, we have devised a "taxonomy" based on seven categories, against which each technology is assessed through a peer-review mechanism. These categories are: 1. Focus area of the technology in question: identify whether the technology relates to (one or more of the following) improving our understanding of source and source physics; propagation modelling; data acquisition; data transport; data processing; broad modelling concepts; quality assurance and data storage. 2. Current Development Stage of the technology in question. Based on a scale from one to six, this measure is specific to PTS needs and broadly reflects Technology Readiness Levels (TRLs). 3. Impact of the technology on each of the following capabilities: detection, location, characterization, sustainment and confidence building. 4. Development cost: the anticipated monetary cost of validating a prototype (i.e. Development Stage 3) of the technology in question. 5. Time to maturity: the number of years until the technology in question reaches Development Stage 3 (i.e. prototype validated). 6. Integration effort: the anticipated level of effort required by the PTS to fully integrate the technology, process, concept or idea into is verification environment. 7. Time to impact: the number of years until the technology is fully developed and integrated into the PTS verification environment and delivers on its full potential. The resulting database is coupled to Pivot, a novel information management software tool which offers powerful visualisation of the taxonomy's parameters for each technology. Pivot offers many advantages over conventional spreadhseet-interfaced database tools: based on shared categories in the taxonomy, users can quickly and intuitively discover linkages, communalities and various interpretations about prospective CTBT pertinent technologies. It is easily possible to visualise a resulting sub-set of technologies that conform to the specific user-selected attributes from the full range of taxonomy categories. In this presentation we will illustrate the range of future technologies, processes, concepts and ideas; we will demonstrate how the Pivot tool can be fruitfully applied to assist in strategic planning and development, and to identify gaps apparent on the technology development horizon. Finally, we will show how the Pivot tool together with the taxonomy offer real and emerging insights to make sense of large amounts of disparate technologies.

Infrasound from lightning measured in Ivory Coast

NASA Astrophysics Data System (ADS)

Farges, T.; Millet, C.; Matoza, R. S.

2012-04-01

It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. More than two thirds (42) of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes, …). Some of the IMS stations are located where worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS infrasound station has been installed in Ivory Coast for 9 years. The lightning rate of this region is 10-20 flashes/km2/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 4 years of data (2005-2009). For short lightning distances (less than 20 km), up to 60 % of lightning detected by WWLLN has been one-to-one correlated. Moreover, numerous infrasound events which have the infrasound from lightning signature could not be correlated when thunderstorms were close to the station. Statistical analyses of all correlated infrasound events show an exponential decrease of the infrasound amplitude with the distance of one order of magnitude per 50 km. These analyses show also that the relative position of lightning is important: the detection limit is higher when lightning occur at the East of the station than when they occur at the West. The dominant wind (the Easterlies) could be responsible of this dissymmetry. It also exists a high variability of detection efficiency with the seasons (better efficiency in fall than in spring). Finally, these statistics show clearly a structure inside the shadow zone (from 70 to 200 km away from the station). These results will be compared with intensive numerical simulations. The simulations are separated into two parts: the simulation of the near-field blast wave generated by a lightning and the simulation of the non-linear propagation of the shock front through a realistic atmosphere. By comparing our numerical results to recorded data over a full 1-year period, we aim to show that dominant features of statistics at the IMS station may be explained by the meteorological variability.

Tsunami Warning Center in Turkey : Status Update 2012

NASA Astrophysics Data System (ADS)

Meral Ozel, N.; Necmioglu, O.; Yalciner, A. C.; Kalafat, D.; Yilmazer, M.; Comoglu, M.; Sanli, U.; Gurbuz, C.; Erdik, M.

2012-04-01

This is an update to EGU2011-3094 informing on the progress of the establishment of a National Tsunami Warning Center in Turkey (NTWC-TR) under the UNESCO Intergovernmental Oceanographic Commission - Intergovernmental Coordination Group for the Tsunami Early Warning and Mitigation System in the North-eastern Atlantic, the Mediterranean and connected seas (IOC-ICG/NEAMTWS) initiative. NTWC-TR is integrated into the 24/7 operational National Earthquake Monitoring Center (NEMC) of KOERI comprising 129 BB and 61 strong motion sensors. Based on an agreement with the Disaster and Emergency Management Presidency (DEMP), data from 10 BB stations located in the Aegean and Mediterranean Coast is now transmitted in real time to KOERI. Real-time data transmission from 6 primary and 10 auxiliary stations from the International Monitoring System will be in place in the very near future based on an agreement concluded with the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) in 2011. In an agreement with a major Turkish GSM company, KOERI is enlarging its strong-motion network to promote real-time seismology and to extend Earthquake Early Warning system countrywide. 25 accelerometers (included in the number given above) have been purchased and installed at Base Transceiver Station Sites in coastal regions within the scope of this initiative. Data from 3 tide gauge stations operated by General Command of Mapping (GCM) is being transmitted to KOERI via satellite connection and the aim is to integrate all tide-gauge stations operated by GCM into NTWC-TR. A collaborative agreement has been signed with the European Commission - Joint Research Centre (EC-JRC) and MOD1 Tsunami Scenario Database and TAT (Tsunami Analysis Tool) are received by KOERI and user training was provided. The database and the tool are linked to SeisComp3 and currently operational. In addition KOERI is continuing the work towards providing contributions to JRC in order to develop an improved database (MOD2), and also continuing work related to the development of its own scenario database using NAMI DANCE Tsunami Simulation and Visualization Software. Further improvement of the Tsunami Warning System at the NTWC-TR will be accomplished through KOERI's participation in the FP-7 Project TRIDEC focusing on new technologies for real-time intelligent earth information management to be used in Tsunami Early Warning Systems. In cooperation with Turkish State Meteorological Service (TSMS), KOERI has its own GTS system now and connected to GTS via its own satellite hub. The system has been successfully utilized during the First Enlarged Communication Test Exercise (NEAMTWS/ECTE1), where KOERI acted as the message provider. KOERI is providing guidance and assistance to a working group established within the DEMP on issues such as Communication and Tsunami Exercises, National Procedures and National Tsunami Response Plan. KOERI is also participating in NEAMTIC (North-Eastern Atlantic and Mediterranean Tsunami Information Centre) Project. Finally, during the 8th Session of NEAMTWS in November 2011, KOERI has announced that NTWC-TR is operational as of January 2012 covering Eastern Mediterranean, Aegean, Marmara and Black Seas and KOERI is also ready to operate as an Interim Candidate Tsunami Watch Provider.

IDCDACS: IDC's Distributed Application Control System

NASA Astrophysics Data System (ADS)

Ertl, Martin; Boresch, Alexander; Kianička, Ján; Sudakov, Alexander; Tomuta, Elena

2015-04-01

The Preparatory Commission for the CTBTO is an international organization based in Vienna, Austria. Its mission is to establish a global verification regime to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which bans all nuclear explosions. For this purpose time series data from a global network of seismic, hydro-acoustic and infrasound (SHI) sensors are transmitted to the International Data Centre (IDC) in Vienna in near-real-time, where it is processed to locate events that may be nuclear explosions. We newly designed the distributed application control system that glues together the various components of the automatic waveform data processing system at the IDC (IDCDACS). Our highly-scalable solution preserves the existing architecture of the IDC processing system that proved successful over many years of operational use, but replaces proprietary components with open-source solutions and custom developed software. Existing code was refactored and extended to obtain a reusable software framework that is flexibly adaptable to different types of processing workflows. Automatic data processing is organized in series of self-contained processing steps, each series being referred to as a processing pipeline. Pipelines process data by time intervals, i.e. the time-series data received from monitoring stations is organized in segments based on the time when the data was recorded. So-called data monitor applications queue the data for processing in each pipeline based on specific conditions, e.g. data availability, elapsed time or completion states of preceding processing pipelines. IDCDACS consists of a configurable number of distributed monitoring and controlling processes, a message broker and a relational database. All processes communicate through message queues hosted on the message broker. Persistent state information is stored in the database. A configurable processing controller instantiates and monitors all data processing applications. Due to decoupling by message queues the system is highly versatile and failure tolerant. The implementation utilizes the RabbitMQ open-source messaging platform that is based upon the Advanced Message Queuing Protocol (AMQP), an on-the-wire protocol (like HTML) and open industry standard. IDCDACS uses high availability capabilities provided by RabbitMQ and is equipped with failure recovery features to survive network and server outages. It is implemented in C and Python and is operated in a Linux environment at the IDC. Although IDCDACS was specifically designed for the existing IDC processing system its architecture is generic and reusable for different automatic processing workflows, e.g. similar to those described in (Olivieri et al. 2012, Kværna et al. 2012). Major advantages are its independence of the specific data processing applications used and the possibility to reconfigure IDCDACS for different types of processing, data and trigger logic. A possible future development would be to use the IDCDACS framework for different scientific domains, e.g. for processing of Earth observation satellite data extending the one-dimensional time-series intervals to spatio-temporal data cubes. REFERENCES Olivieri M., J. Clinton (2012) An almost fair comparison between Earthworm and SeisComp3, Seismological Research Letters, 83(4), 720-727. Kværna, T., S. J. Gibbons, D. B. Harris, D. A. Dodge (2012) Adapting pipeline architectures to track developing aftershock sequences and recurrent explosions, Proceedings of the 2012 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, 776-785.

REPORT OF THE ISS OSI INVITED MEETING, VIENNA, 24-27 MARCH, 2009

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sweeney, J J

2009-04-17

The International Scientific Studies project (ISS) was initiated in early 2008 with the objective of creating a series of activities aimed at application of modern scientific methods to improve the efficiency of analysis and the quality of verification of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO). The ISS On-Site Inspection (OSI) Invited Meeting convened on March 24, 2009 with the objectives of gaining a better understanding of the phenomenology of underground nuclear explosions (UNE) for OSI purposes and to identify areas of interest to OSI that could benefit significantly from contributions by the general scientific community. Fifteen invited experts frommore » four countries, along with fifteen members of the OSI Division of the Provisional Technical Secretariat (PTS) met for four days at the Vienna International Center in an informal setting to discuss the application of observational methods, geophysical techniques, radionuclide measurement methods, environmental sampling methods, drilling techniques, and information management in the context UNE phenomena and OSI implementation. The meeting began with the identification and description of two general OSI scenarios, a vertical borehole emplacement and a horizontal tunnel emplacement, that serve as general examples of past UNE testing activities that can be used as a reference to identify UNE phenomena relevant for OSI observations. A significant portion of the first day of the meeting was spent in the description of the details of these scenarios and their implications for OSI observables. This discussion then served as a foundation for the discussions of the following three days in which OSI methods and technologies were evaluated in the context of UNE phenomenology and signatures. The methods and technologies discussed included visual observation from air and ground, radiation detection from the air, ground, and subsurface, ground-based and airborne geophysical observations and analysis, collection strategies for air, water, and solid samples, drilling concepts, and aspects of data fusion, information management, and modeling and simulation. The informal setting of the meeting provided a 'brainstorming' atmosphere and participation was excellent. One important aspect of this particular group was the very wide breadth of experience and expertise represented, ranging from those sharing their knowledge of UNE testing practice, radiological measurements and sampling, and knowledge of the underground effects of UNEs, to those with extensive experience in scientific and commercial geophysical measurements and surveys, to others with rich experience gained from several OSI field exercises, including the recent OSI Integrated Field Exercise in held in Kazakhstan in September 2008. During the workshop a number of topic areas relevant to OSI, explained in the list below, were identified that will benefit from collaboration with the international scientific community. Most of the topics represent the potential for studies of long-term interest, but some topics were identified that could be addressed, either by workshop participants or others known to the participants, that could be included as abstracts for submission to the ISS meeting taking place in June 2009. Items with topics that could be covered in the June meeting are annotated in the list. The meeting ended with the general understanding that ISS will not be completed with the June 2009 Conference. Rather, the ISS is considered as a long term project sponsoring relevant ongoing international scientific initiatives to expand and improve the verification capabilities of the Comprehensive Nuclear Test-Ban Treaty.« less

Monitoring the Earth's Atmosphere with the Global IMS Infrasound Network

NASA Astrophysics Data System (ADS)

Brachet, Nicolas; Brown, David; Mialle, Pierrick; Le Bras, Ronan; Coyne, John; Given, Jeffrey

2010-05-01

The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is tasked with monitoring compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) which bans nuclear weapon explosions underground, in the oceans, and in the atmosphere. The verification regime includes a globally distributed network of seismic, hydroacoustic, infrasound and radionuclide stations which collect and transmit data to the International Data Centre (IDC) in Vienna, Austria shortly after the data are recorded at each station. The infrasound network defined in the Protocol of the CTBT comprises 60 infrasound array stations. Each array is built according to the same technical specifications, it is typically composed of 4 to 9 sensors, with 1 to 3 km aperture geometry. At the end of 2000 only one infrasound station was transmitting data to the IDC. Since then, 41 additional stations have been installed and 70% of the infrasound network is currently certified and contributing data to the IDC. This constitutes the first global infrasound network ever built with such a large and uniform distribution of stations. Infrasound data at the IDC are processed at the station level using the Progressive Multi-Channel Correlation (PMCC) method for the detection and measurement of infrasound signals. The algorithm calculates the signal correlation between sensors at an infrasound array. If the signal is sufficiently correlated and consistent over an extended period of time and frequency range a detection is created. Groups of detections are then categorized according to their propagation and waveform features, and a phase name is assigned for infrasound, seismic or noise detections. The categorization complements the PMCC algorithm to avoid overwhelming the IDC automatic association algorithm with false alarm infrasound events. Currently, 80 to 90% of the detections are identified as noise by the system. Although the noise detections are not used to build events in the context of CTBT monitoring, they represent valuable data for other civil applications like monitoring of natural hazards (volcanic activity, storm tracking) and climate change. Non-noise detections are used in network processing at the IDC along with seismic and hydroacoustic technologies. The arrival phases detected on the three waveform technologies may be combined and used for locating events in an automatically generated bulletin of events. This automatic event bulletin is routinely reviewed by analysts during the interactive review process. However, the fusion of infrasound data with the other waveform technologies has only recently (in early 2010) become part of the IDC operational system, after a software development and testing period that began in 2004. The build-up of the IMS infrasound network, the recent developments of the IDC infrasound software, and the progress accomplished during the last decade in the domain of real-time atmospheric modelling have allowed better understanding of infrasound signals and identification of a growing data set of ground-truth sources. These infragenic sources originate from natural or man-made sources. Some of the detected signals are emitted by local or regional phenomena recorded by a single IMS infrasound station: man-made cultural activity, wind farms, aircraft, artillery exercises, ocean surf, thunderstorms, rumbling volcanoes, iceberg calving, aurora, avalanches. Other signals may be recorded by several IMS infrasound stations at larger distances: ocean swell, sonic booms, and mountain associated waves. Only a small fraction of events meet the event definition criteria considering the Treaty verification mission of the Organization. Candidate event types for the IDC Reviewed Event Bulletin include atmospheric or surface explosions, meteor explosions, rocket launches, signals from large earthquakes and explosive volcanic eruptions.

Infrasonic detection performance in presence of nuisance signal

NASA Astrophysics Data System (ADS)

Charbit, Maurice; Arrowsmith, Stephen; Che, Il-young; Le Pichon, Alexis; Nouvellet, Adrien; Park, Junghyun; Roueff, Francois

2014-05-01

The infrasound network of the International Monitoring System (IMS) consists of sixty stations deployed all over the World by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The IMS has been designed to reliably detect, at least by two stations, an explosion greater than 1 kiloton located anywhere on the Earth [1]. Each station is an array of at least four microbarometers with an aperture of 1 to 3 km. The first important issue is to detect the presence of the signal of interest (SOI) embedded in noise. The detector is commonly based on the property that the SOI provides coherent observations on the sensors but not the noise. The statistic of test, called F-stat [2], [5], [6] , calculated in a time cell a few seconds, is commonly used for this purpose. In this paper, we assume that a coherent source is permanently present arriving from an unknown direction of arrivals (DOA). The typical case is the presence of microbaroms or the presence of wind. This source is seen as a nuisance signal (NS). In [4], [3] authors assume that a time cell without the SOI (CH0) is available, whereas a following time cell is considered as the cell under test (CUT). Therefore the DOA and the SNR of the NS can be estimated. If the signal-to-noise ration SNR of the NS is large enough, the distribution of the F-stat under the absence of SOI is known to be a non central Fisher. It follows that the threshold can be performed from a given value of the FAR. The major drawback to keep the NS is that the NS could hide the SOI, this phenomena is similar to the leakage which is a well-known phenomena in the Fourier analysis. An other approach consists to use the DOA estimate of the NS to mitigate the NS by spatial notch filter in the frequency domain. On this approach a new algorithm is provided. To illustrate, numerical results on synthetical and real data are presented, in term of Receiver Operating Characteristic ROC curves. REFERENCES [1] Christie D.R. and Campus P., The IMS infrasound netwrok: design and establishment of infrasound stations, Infrasound Monitoring for Atmospheric Studies, Springer Netherlands, Editor: Le Pichon, Alexis and Blanc, Elisabeth and Hauchecorne, Alain, pp 27-72, 2010. [2] Shumway R. H.,Advances in Mixed Signal Processing for Regional and Teleseismic Arrays 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, pp 503-509, 2007. [3] Park J., Hayward C.T., Zeiler C. P., Arrowsmith S.J. and Stump B.W., A Comparative Study of Automated Infrasound Detectors - PMCC and inframonitor with analyst review, SSA Annual Meeting, 2013. [4] Arrowsmith S.J., Whitaker R., Katz C. and Hayward C., The F-Detector Revisited: An Improved Strategy for Signal Detection at Seismic and Infrasound Arrays, Bulletin of the Seismological Society of America, 2008. [5] Arrowsmith S.J., Whitaker R., Steven R. Taylor, Burlacu R., Stump B.W., Hedlin M.A.H., Randall G., Hayward C. and ReVelle D., Regional monitoring of infrasound events using multiple arrays: application to Utah and Washington State, Geophys. J. Int., vol.175, pp 291-300, 2008. [6] Charbit M., Gaillard P. and Le Pichon A., Evaluating the performance of infrasound detectors, EGU, Vienne, Autriche, April 2012.

Tropical deep convection and density current signature on surface pressure: comparison of idealized and real WRF simulations with infra-sounder measurements

NASA Astrophysics Data System (ADS)

Costantino, Lorenzo; Heinrich, Philippe

2013-04-01

In the framework of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project, which proposes to design a new infrastructure to integrate different atmospheric observation networks, we analyse moist deep convective processes responsible of intensive rainstorms in the tropics (making use of the Weather Research and Forecasting, WRF, numerical model) and compare the results with ground measurements of the CTBTO (Comprehensive nuclear-Test-Ban Treaty Organization) infra-sound stations in Ivory Coast. In this work, we investigate the life cycle of singlecell deep convective cloud trough a bi-dimensional, non-hydrostatic, limited-area simulation in simplified model configuration ("idealized case"), at high spatial and temporal resolution. In this way, we expect to resolve explicitly the convective cloud dynamics, avoiding the use of sometimes questionable parametrization (e.g. PBL and convective cumulus) schemes. We also perform a three-dimensional numerical experiment at coarser resolution, guided by real meteorological data of the tropical Ivory Coast region, to compare "real case" results with the infra-sounder measurements for the same area. Previous studies have shown that rain evaporation during intense precipitating events may cool the atmosphere and produce negative buoyancy that, together with falling rain, may give rise to particularly strong down-drafts (Betts, 1976, Tompkins, 2000). As the descending air column impacts the ground, it spreads out and creates a horizontal surface outflow (generally called "density current" or "cold pool") colder and denser than surrounding air. Results from the 2D idealized case show that temporal and horizontal resolution of 2 seconds and 250 meters is fine enough to produce a density current, that moves outward up to several kilometers from storm center. The increase in surface density (up to 2% higher than the base state) is followed by a sudden variation of surface temperature and an increase in horizontal wind speed (between 10 and 20 m/s), somewhat proportional to the density change. We note that if the surface density variation is strong and rapid enough, the surface pressure filed results strongly affected as well. We observe a surface pressure peak (with maximum amplitude of about ±40 Pa), that moves together with the density current leading edge. At cold pool boundaries, the outflow converges with warmer and moister surface inflow and create a curl. As a consequence, warmer air is lifted up and transported above the denser layer where it may trigger new convection and provide the vapor supply to new cloud formation. Results from the 3D real data case (that uses a horizontal resolution of 2 km and a convective cumulus parametrization scheme) show a very good agreement with ground measurements of pressure, wind speed and wind direction and confirm that this model configuration reliably reproduces the dynamical and thermodynamical evolution of a tropical deep convective storm. The simulated pressure peak (due to a strong density current that originates from a huge precipitating squall line) is very similar to that measured by the infra-sounders (with maximum amplitude of about ±50 Pa) and coherent with the idealized case. As in the 2D experiment, the development of tropical heavy rain events associated with strong density currents leads to a sub cloud layer which is not only denser and colder (as a consequence of rain evaporation, that works as a heat sink) but also sensibly dryer in correspondence of the gust front, sing that saturation mixing ration of subsiding air is lower than that of the boundary layer.

An Evaluation of North Korea’s Nuclear Test by Belbasi Nuclear Tests Monitoring Center-KOERI

NASA Astrophysics Data System (ADS)

Necmioglu, O.; Meral Ozel, N.; Semin, K.

2009-12-01

Bogazici University and Kandilli Observatory and Earthquake Research Institute (KOERI) is acting as the Turkish National Data Center (NDC) and responsible for the operation of the International Monitoring System (IMS) Primary Seismic Station (PS-43) under Belbasi Nuclear Tests Monitoring Center for the verification of compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) since February 2000. The NDC is responsible for operating two arrays which are part of the IMS, as well as for transmitting data from these stations to the International Data Centre (IDC) in Vienna. The Belbasi array was established in 1951, as a four-element (Benioff 1051) seismic array as part of the United States Atomic Energy Detection System (USAEDS). Turkish General Staff (TGS) and U.S. Air Force Technical Application Center (AFTAC) under the Defense and Economic Cooperation Agreement (DECA) jointly operated this short period array. The station was upgraded and several seismometers were added to array during 1951 and 1994 and the station code was changed from BSRS (Belbasi Seismic Research Station) to BRTR-PS43 later on. PS-43 is composed of two sub-arrays (Ankara and Keskin): the medium-period array with a ~40 km radius located in Ankara and the short-period array with a ~3 km radius located in Keskin. Each array has a broadband element located at the middle of the circular geometry. Short period instruments are installed at depth 30 meters from the surface while medium and broadband instruments are installed at depth 60 meters from surface. On 25 May 2009, The Democratic People’s Republic of Korea (DPRK) claimed that it had conducted a nuclear test. Corresponding seismic event was recorded by IMS and IDC released first automatic estimation of time (00:54:43 GMT), location (41.2896°N and 129.0480°E) and the magnitude (4.52 mb) of the event in less than two hours time (USGS: 00:54:43 GMT; 41.306°N, 129.029°E; 4.7 mb) During our preliminary analysis of the 25th May 2009 DPRK event, we saw a very clear P arrival at 01:05:47 (GMT) at BRTR SP array. The result of the f-k analysis performed in Geotool software, installed at NDC facilities in 2008 and is in full use currently, was also indicating that the arrival belongs to the DPRK event. When comparing our f-k results (calculated at 1-2 Hz) with IDC-REB, however, we have noticed that our calculation and therefore corresponding residuals (calculated with reference to REB residuals) are much better in comparison to REB. The reasons of this ambiguity have been explored and for the first time a comprehensive seismological analysis of a Nuclear Test has been conducted in Turkey. CTBT has an important role for the implementation of the non-proliferation of nuclear weapons and it is a key element for the pursuit of nuclear disarmament. In this study, we would like to reflect the technical and scientific aspects of the 25 May 2009 DPRK event analysis, together with our involvement in CTBT(O) affairs, which we believe it brings new dimensions to Turkey especially in the area of Geophysics.