Well-constrained acoustic waveform inversion can provide robust estimates of explosion source parameters, increasing our ability to monitor anthropogenic and natural explosions. Previous volcanic studies have generally assumed a simple acoustic source (monopole), however more complex source reconstructions can be estimated using a combination of monopole and dipole sources (multipole). We...
The ability of the International Monitoring System (IMS) global infrasound network to detect atmospheric explosions and events of interest strongly depends on station specific ambient noise signatures which include both incoherent wind noise and coherent infrasonic waves. Understanding the detectability of coherent noise in the frequency range of explosions is important for successfully...
InfraPy is a Python-based infrasound analysis toolkit being developed at Los Alamos National Lab for detection, association, localization, and characterization using infrasonic signals. The software is intended to eventually provide a complete suite of tools for infrasonic signal analysis. The use of the Python language allows for fast development through a wealth of built in libraries and...
For the permanent station in South-Korea, we try to expand our Government infrasound station in the future. About past experience on the running permanent station, the Government face several problem related atmospheric activity. It was lighting and weathering from the nature. For the acceptable location as good as possible, we pick the several feature which makes station more stable from the...
Wide infrasound coverage is obtained using fixed, land-based monitoring stations. However, two-thirds of the earthâs surface is composed of oceans, and while some sensing stations are located on islands, no capability yet exists to monitor infrasound from sensors fielded directly in the maritime environment. We investigate the potential of fielding microbarometer sensors on persistent,...
The infrasound technology system has been designed for the detection of atmospheric nuclear explosions and/or Natural disaster and pressure fluctuations produced in the frequency range. The majority of the monitoring chains used in this network also record pressure fluctuations at lower frequencies. Also, the infrasound technology is the one of the International Monitoring System (IMS) network...
The traveltimes difference surveying of infrasound detection array is one of key factors that affects the accuracy of infrasound source localization. In this paper, the main methods of calculation the traveltimes difference of infrasound detection array are introduced, and then analyze on common method for improving the accuracy of the traveltimes difference calculation. Based on the...
Accurate element-to-element correlation of incoming signals is important for good infrasound-station performance. For example, mismatches in phase response can result in errors in azimuth estimation. These mismatches can be identified through in-situ calibration. Although the impact of nonlinearity on array performance is not as well known, waveform distortion has the potential to affect...
JPL and its partners are in the process of developing new technology for the detection of infrasonic waves generated by seismic activity from a balloon in order to achieve the aim of performing geophysical experiments from an atmospheric platform. This technique is being developed for application on planetary bodies with significant atmospheres, such as Titan and Venus. In particular, the...
A series of events originating from Balakliia and Kalynivka both in Ukraine were recorded by the IMS network on 23 March 2017 and from the evening of September 26, 2017 to September 27, 2017 respectively. The location of events was estimated with seismic (AKASG, FINES) and infrasound (I43RU, I26DE, I31KZ, I37NO) monitoring data obtained from these IMS stations that recorded these events using...
IS32 is a seven element primary array station situated about 10KM outside the capital city of Nairobi. Because of its location, the station faced major operation and maintaince challenges in the past. Having addressed most of the life cycle challenges ,we have now embarked on the civil and scientific application of data that is collected and transmitted to both the IDC in Vienna and the NDC-KE...
The cross-wind effect on infrasound propagation has been studied on the seismic array ARCES, Norway, utilizing 30 years of data from explosions at the Hukkakero military blast-site in Finland. Around 99% of the seismically identified explosions at Hukkakero (around 600 in total) are detected as seismo-acoustic signatures around 10 minutes after the arrival of the original P- and S-waves,...
After six months deployment (January to June), CTBTO infrasound mobile array (I68CI) data has been processing in three frequencies bands. The frequencies bands are the following 1 to 0.1Hz for the distant detections, 2.5 to 0.5Hz for the regional detections and 4 to 2Hz for the local detections. From January to February, the local, regional and distant detections azimuths are from Northwest....
Ambient noise varies both in space and time, resulting in multiple source locations with varying strength. Interfering sources are not always correctly resolved when classical beamforming methods are applied. Various beamforming methods exist in literature for a better discrimination of multiple continuous sources. One of these methods, CLEAN, is discussed here. The CLEAN method iteratively...
In order to assess the feasibility of the installation of an infrasound array on the campus of Nanyang Technological University (NTU) a temporary deployment of the Seismo Wave MB3d microbarometers is being designed and carried out. This system uses Raspberry Pi 3 B (RPi) microcomputers for data collection, archiving, and data streaming via Wi-Fi and Ethernet. The use of RPi allows for a...
The Mw 6.2 Amatrice earthquake that struck central Italy on 24 August 2016 was recorded by 7 infrasound arrays in the Euro-Mediterranean region at distances up to 1260 km, recordeding long lasting coherent wave trains characterized by large back-azimuth variations. The back projection of the stratospherically ducted infrasound illuminates radiating regions over ∼600 km along the Apennines from...
I68CI is an infrasound portable array deployed in the North-East of Cote d’Ivoire since January 2018. This project is the result of collaboration between CTBTO and the Station Geophysique de Lamto, the ivorian NDC. The sensor used is the MB3d, developped by the French Renewable and Atomic Commission (CEA) and manufactured by SeismoWave. It is made of a MB3a microbarometer with a digitizer in...
It is a daunting task to frame the fearful symmetry of a blast. Properties and defining characteristics of theoretical source pressure functions representative of detonations and deflagrations are considered, and criteria for defining reference blast pulses are discussed. A new impulse-balanced blast pulse is proposed as a reference signature for propagation model initialization, the design of...
Infrasonic signatures associated with the maiden flight of SpaceX Falcon Heavy are presented. IMS and open source data (Twitter, YouTube, RedVox) are integrated to examine various aspects of the complex sequence.
Recent earthquakes in the Alaska region have generated a set of interesting seismo-acoustic coupled signals that have been detected by an International Monitoring System (IMS) array, I53US, local infrasound arrays of the Alaska Volcano Observatory (AVO), and some stations of the EarthScope Transportable Array (TA) that is currently deployed in Alaska and western Canada. In this study we...
In the early morning of 29 May 2017, unusually large waves of over 2 m height hit the west coast of the Netherlands, leading to some property damage. The waves were due to a meteo-tsunami, which is a tsunami of meteorological origin, unlike seismogenic tsunamis. This particular event was caused by a rapidly moving cold front which featured a sharp squall line that moved towards the coast....
The IDC advances its methods and continuously improves its automatic system for the infrasound technology. The IDC focuses on enhancing the automatic system for the identification of valid signals and the optimization of the network detection threshold by identifying ways to refine signal characterization methodology and association criteria. An objective of this study is to reduce the number...
The completion of IDC event bulletins requires that infrasound array detector be tuned to detect wide variety of acoustic signals, often buried in the background noise. Dominant frequencies of signals of interest can span over 3 decades (from 0.01Hz to 10Hz), depending on source energy, frequency-dependent attenuation along different propagation paths and noise conditions which can vary...
Infrasound signal detection and source characterization relies on high-quality array processing parameter estimates. Physical and statistical assumptions in conventional array processing techniques sometimes fail due to propagation effects or station degradation. Unlike conventional least squares, robust regression estimators are relatively insensitive to data that deviate from the assumed...
Japan's satellite and probe carrying rocket (H-IIA, H-IIB and Epsilon) have been launched by JAXA (Japan Aerospace Exploration Agency) at Tanegashima or Uchinoura Space Center in southern Japan. Multiple infrasonic signals generated by these launched rockets are detected at I30JP from 2005, when the operation started. We have been organizing the data and the knowledge by accumulating the...
It is nearly impossible for an analyst to categorize regional and global infrasound events by eye. Currently, categorizing these events requires removing false detections and using seismic or other forms of data as ground truth. We explore two machine learning approaches, support vector machine (SVM) and deep learning (Convolutional Neural Network) to determine their potential for...
Supersonic rockets generate low-frequency acoustic waves, i.e., infrasound, during the launch and re-entry. Infrasound is routinely observed at infrasound arrays from the International Mon- itoring System, in place for the verification of the Comprehensive Nuclear-Test-Ban Treaty. Association and source identification are key elements of the verification system. The moving nature of a rocket...
A bright fireball was reported at 12:07:05 UTC on October 4, 2017 at a height of ～37 km above 28.1N, 99.4E near Shangri-La, the western of Yunnnan of China. It had a TNT yield equivalent of 0.54 kilotons (kt). Infrasonic signals were observed by I16 infrasound array that is part of the International Monitoring System (IMS) and Tengchong infrasound array located in the western of Yunnnan of...
The Facility for Acceptance, Calibration and Testing (FACT) at Sandia National Laboratories has been a valued resource for the U.S. monitoring community for decades. The FACT site hosts a number of capabilities focused on component evaluation including a recently added acoustic chamber, which provides superior isolation for sensors-under-test from the acoustic and pressure environment, and has...
On June 2nd, 2018, around 16h44 UT, Bolide impacted the Earth atmosphere over Botswana, near South Africa border. This event was recorded at some IMS infrasound arrays in Southern Africa. Data analysis were performed using WinPMCC software (CEA/DASE) based on PMCC method (Y. Cansi,1995). A pass-band frequency between 0.1 Hz and 4 Hz is applied to detect the source. Results using I47ZA station...
The challenge for infrasound calibration is to measure the response of the operational microbarograph sensor connected to the wind-noise reduction system (WNRS). Gabrielson (2011) proposed a passive method using a calibrated reference sensor with no WNRS located beside the operational sensor. This passive on-site calibration technique at certified IMS stations has been implemented in the...
As part of signatory states and despite the absence of International Monitoring System (IMS) stations in its territory, Iraqi National Data Center (NDC) as an organization working under the Treaty Verification and an integral part of national Authority in monitoring to implement this Treaty we took benefits from Comprehensive Nuclear-Test-Ban Organization (CTBTO) and its four technologies...
The apparent velocity and backazimuth of infrasound signals on arrays can be estimated in many ways. Estimates can vary significantly with the methods and parameters used, and with signal coherence. Larger arrays, with many sensors, allow measurement of the slowness on many different subsets of sensors. On IMS infrasound arrays with aperture 1-2 km, and with over 8 sensors, we can form...
In the South-West Indian Ocean, tropical cyclones occur every year from December to April which can generate infrasonic signals in the 0.1-0.5 Hz frequency band and propagate into thousands of kilometers. Generation mechanism of microbarom signals is attributed to the nonlinear interaction of surface ocean waves and radiated acoustically only if the swells are almost opposite in direction and...
The Kazakh monitoring network consists of five seismic and three infrasound arrays. Seismic arrays are ABKAR, BVAR, KKAR, MKAR and Kurchatov Cross. Infrasound arrays are I31KZ, Kurchatov and Makanchi infrasound arrays. KazNDC also processes data of the Russian infrasound array I46RU. All the arrays record low-frequency signals mostly from North-West. A dominating source region of...
In the frame of its activities in exploiting the IMS Data for civil and scientific applications including security ones, the Tunisian NDC is initiating some projects at national level like the acquisition of an infrasound portable station (to be deployed in several sites in order to discriminate events sources) as well as the reinforcement of the cooperation at the national level in order to...
This paper considers infrasonic characterization of run-off and calving events from glaciers using I18DK data (Qaanaaq, Greenland). We seek to localise observed near-field sources of infrasound. The estimated curvature of the spherical wavefront may provide information on the location of the source. We suggest the Q-tau parameter as a tool to discriminate between far-field (plane) waves and...
Collaboration between OVSICORI-UNA and the Provisional Technical Secretariat of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). The deployment and installation of a CTBTO infrasound mobile system in Costa Rica, would be beneficial for advancing the urderstanding of infrasonic sources in Central, Latin American and Caribbean regions. The proposed...
Industrial activity has a significant impact in the local and regional seismic-acoustic wavefield. The repetitive nature of industrial processes generates persistent elastic energy that can be observed at distances of several 10’s of kilometers. The signature of this activity is observed as a mixture of both broadband and tonal noise (TN) in seismic and acoustic/infrasonic records. TN is...
This presentation discusses on-going research in Infrasound at Georgia Tech Research Institute (GTRI), the applied research arm of Georgia Institute of Technology. In particular, results of a study that compared a number of commercially available infrasound sensors with and without a wind screen loaned to GTRI by NASA Langley and described by Ahuja and Shams in the 2017 Infrasound Workshop are...
A major upgrade has been carried out during 2017 at French Polynesian infrasound station IS24. The station is operational from November 2017, and is planned to be re-validated in October 2019. The renewals and changes of hardware are described. Among those upgrade actions, the most significative one is the installation of 2 infrasound sensors at each element of the station. The new operational...
The results of the evaluation of the pressure-to-seismic transfer function for periods between 1 to 100 s obtained on the base of the seismic and acoustic waves associated with the 2013 Chelyabinsk meteorite, Russia, are presented. According to NASA report, the meteorite’s breakup was fixed around 03:20 UTC. In previous study was shown that coupling between the meteorite’s shock wave and...
Previous testing has shown that infrasound sensors deployed in the field can exhibit notable deviations from their lab-based calibrations. These variations may in-part be due to changes in environmental conditions (e.g. temperature), long-term sensor drift, or other unresolved features. In early 2018 we installed two identical test elements at the Sandia National Labs FACT site with five...
Moderate shallow earthquake occurred December 5, 2014 (MW=4.9) in the north of Lake Hovsgol (Mongolia). The infrasonic signal with duration 140 seconds was recorded for this earthquake by infrasound station "Tory". Source parameters of the earthquake (seismic moment, source radius, displacement) were received by spectra analysis of direct body waves. The analysis of seismograms and amplitude...
Reciprocity calibration is a well-established primary calibration technique, a technique that does not require an independently-calibrated acoustic reference. In its most general form, reciprocity requires two transducers in addition to the sensor being calibrated; however, the responses of these transducers do not need to be known. The transmitting and receiving responses of the two...
SEISMO WAVE has designed and developed a new facility and the environmental conditions suitable for a laboratory dedicated to the infrasound metrology activity. Since September 2017, an infrasound sensor calibration bench designed by CEA and some reference sensors are installed in this laboratory.
A qualification of the calibration process has been carried out in collaboration with CEA in...
Kazakhstan has established and is successfully operating a contemporary digital network of seismic and infrasound stations located throughout the perimeter of the Republic. Currently, KNDC transmits in real time and processes data from 4 infrasound arrays: Aktybinsk, Kurchatov, Makanchi, Zalesovo (Russia). This data allows for automated detection of infrasound events, and creating infrasound...
On the first of September 2018, a devastating explosion occurred on the facility of an oil refinery near Ingolstadt, Germany. We analyzed data of 400 permanent and temporary seismic stations within 400 km radius from the explosion site and find strong seismo-acoustic signals on more than 80 seismic stations. Thanks to the dense spatial coverage of the AlpArray seismic network, the infrasound...
On December 12, 2017 a devastating gas explosion occurred at the Baumgarten gas hub in Eastern Austria. We detected the resulting seismo-acoustic signal on permanent and temporary broadband seismic stations at distances between 30 and 175 km from the gas hub, most prominently in the 2-4 Hz range. Two distinct phase arrivals correspond to acoustic waves traveling through the troposphere and...
Sources of opportunity play a key role in expanding our understanding of source physics and validating propagation models. For dynamic sources, such as rockets, the modeling is complicated by the body’s motion through the propagation medium. Supersonic sources pose the additional challenge of introducing nonlinear propagation effects. Previous research efforts in this area have successfully...
Acoustic pressure signals recorded for numerous explosions and several azimuths in the vicinity of an outdoor pyrotechnic site of the South of France are used to validate a fully nonlinear numerical code. This code, based on direct simulation of Euler equations with a detonation model and state of the art numerical schemes, allows classifying relative effects of topography, vegetation, and...
Infrasound monitoring is an effective method for monitoring the atmosphere and shallow explosions. And during the infrasound monitoring, the slowness and azimuth are very important for the infrasound signal propagation, location and infrasonic sources recognition. The common method for the slowness and azimuth is the frequency-wavenumber(FK) method, but when the FK is applied to the infrasound...
Infrasound sources could be classified as man-made and natural sources. The first category includes explosions while the second includes earthquakes, volcanoes, fireball, and meteorites. In this paper the different sources are processed using the Progressive Multi-Channel Correlation algorithm (PMCC) which is a very effective technique in array analysis. This technique correlates the signals...
A general method for producing a statistical model for infrasound signal transmission from a large sample of atmospheric specifications has been developed. Applying this method to historical archives of atmospheric specifications, statistical transmission loss maps are developed. These depend on season of the year. It is found that propagation characteristics divide the year into four...
On 12 December 2017 a heavy detonation occured near Baumgarten about 30 km east of Vienna, Austria, around 9 am local time. Seismo-acoustic signals were detected at AlpArray seismic stations up to 150 km distance (Schneider et al., 2018) providing evidence from 3D raytracing for both tropospheric and stratospheric arrivals and inferring an origin time of 7:44:16 UTC. The infrasound array PSZI...
Volcanic infrasound is generated during the explosive release of fluid into the atmosphere. Several acoustic signals were recorded between May and August 2018 at the IMS-station IS59 on Hawaii during explosive eruptions at Kilauea Volcano. The sequence started with an earthquake at May 4th 2018. Detected signals are either based on elastic body waves or as infrasound generated by the...
A new regional collaboration between four countries has been founded for the establishment of the Eastern European Infrasound Network. The network is formed by three infrasound arrays in Romania, two in Czechia and one in Hungary, and one more array is to be deployed later in this year in Austria. A Memorandum of Understanding for the collaboration was signed by the representatives of the...
The duration of infrasonic signals recorded by sensors on the Earth’s surface increases with source-to-receiver distance, due to the increased separation of the fastest and slowest portions of the wavefield. 43 infrasound signals exhibiting high signal-to-noise ratios within the 0.32 to 1.28Hz passband, and generated by well-constrained ground truth events, have been analyzed using an...
The experimental data on the amplitude-time parameters p+, p-, t+, t- of the first positive and negative phases of acoustic waves in the atmosphere generated by pulse sources of different nature are analyzed. By comparing these data with the results of numerical simulation of spherical and cylindrical propagation of blast waves in homogeneous atmosphere, the effects of stability of the...
The International Monitoring System (IMS) infrasound network has been designed to acquire the necessary data to detect and locate explosions in the atmosphere with a yield equivalent to 1 kiloton of TNT anywhere on Earth. A major associated challenge is the task of automatically processing data from all IMS infrasound stations to identify possible nuclear tests for subsequent review by...
The infrasound component of the International Monitoring System (IMS), often referred to as the IMS infrasound network, is composed of sixty stations. Fifty-one of these stations are already certified and transmit data in near real-time to the International Data Centre, Vienna, Austria. The Provisional Technical Secretariat (PTS) of the Preparatory Commission for the Comprehensive...
The theory of the infrasound wave propagation states that the acoustic waves of infrasound sources, related with wind and temperature conditions, can be detected in distance of 200-250 km (McKenna, 2005; Golden et al., 2007). From our seasonal observations (winter and summer monitoring) and research studies, we would like to determine a detection level of infrasound waves in the north...
Infrasound chambers are commonly used to calibrate infrasound sensors using a dynamic piston to generate pressure variations and a calibrated reference sensor against which to compare the observations of pressure. The reference sensor that is used in such a calibration system requires periodic recalibration in order to maintain traceability. As an alternate approach to traceability, the 1400...
PTS portable infrasound array (I67RO) has been deployed in September 2016, in western Romania, for one-year experiment, within a collaboration project between National Institute for Earth Physics (NIEP) and PTS/CTBTO. Operated and maintained in the framework of Romanian infrasound monitoring network, I67RO array has been proven effective in supporting NIEP efforts for monitoring of natural and...
Waveform inversion techniques are widely used to constrain source dynamics of infrasound. The methods exploit full-waveform information and provide further constraints on source parameters than other inversions using only a few observation parameters. Infrasound waveform inversion was recently applied to volcanic eruptions and chemical explosions and showed promising results for source...
The 2017 North Korean nuclear test gave rise to seismic and low-frequency acoustic signals, that is, infrasound. The infrasonic signals are due to seismo-acoustic coupling and have been detected on microbarometer array I45RU in the Russian Federation at 401 km from the test site. We analyze the seismo-acoustic coupling by making use of array-processing and backprojection techniques. The...
Monitoring the atmosphere and shallow underground phenomenon for low frequency acoustic waves is the CTBT’s infrasound sensors deployed to detect any nuclear explosion signatures anywhere by anyone around the planet. This network also monitors and detects infrasound signals from non-verification-related explosion events either from man‐made or natural sources. Such a data has been of immense...
An estimated average of 54 tons of extra-terrestrial material enter Earth’s atmosphere per day. If the objects are large enough they can produce very bright meteors, called fireballs. NEMO (NEar real-time MOnitoring system) will analyse fluxes and characteristics of extra-terrestrial material by globally searching for fireballs in near real-time. Ground-based networks exist for meteor/fireball...
The dynamic and poorly sampled nature of the atmosphere has posed an ongoing challenge in infrasound propagation modeling applications due to the associated uncertainty in the acoustic propagation medium. Propagation-based, stochastic models defining seasonal trends in path geometry and travel times as well as transmission loss have been constructed using archived atmospheric specifications...
Infrasound is one of the three waveform technologies of the Comprehensive Test Ban Treaty (CTBT) verification regime. Its primary application is to detect and locate atmospheric nuclear tests. The International Monitoring System (IMS) network also records other sources of infrasound signals like bolides, spaceflight activity, sonic booms, volcanic eruptions, quarry blasts, earthquakes,...
One ongoing challenge to the use of infrasound for long-range monitoring applications (e.g., remote explosions or natural sources of infrasound such as tornados, volcanos or hurricanes) continues to be the high noise floors experienced at many permanent infrasound stations. International Monitoring System (IMS) infrasound stations typically address this problem using large pipe arrays as wind...
