IDC Infrasound technology development

Thursday, 18 December 2014
Pierrick Mialle, David John Brown, Ronan Le Bras, Maurice jean-claude Charbit and Jeffrey W Given, CTBTO Preparatory Commission for the Comprehensive Nuclear Test-Ban Organization, Vienna, Austria
The first atmospheric event built only from infrasound arrivals was reported in the Reviewed Event Bulletin (REB) of the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) in 2003. In the last decade, 48 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The infrasound component of the IMS daily registers infragenic signals originating from various sources such as volcanic eruptions, earthquakes, microbaroms, meteorites entering the atmosphere and accidental explosions. The IDC routinely and automatically processes infrasound data reviewed by interactive analysis; the detected and located events are then included in the IDC products.

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 of associated infrasound arrivals that are rejected from the automatic bulletins when generating the reviewed event bulletins. A number of ongoing projects at the IDC will be presented, such as:

- improving the detection accuracy at the station processing stage by enhancing the infrasound signal detector DFX-PMCC (Detection and Feature eXtraction – Progressive Multi-Channel Correlation) and by evaluating the performances of detection software.

- separating infrasound data from other waveform technologies at the automatic network processing stage for technology development and for preparing the implementation of next generation of waveform association algorithm. Infrasound rules in Global Association (GA) are revisited to pursue a lower ratio of false alarms.

- determining station noise for IMS infrasound, seismic and hydroacoustic stations sending data to the IDC. The data is used for assessing the network capability performances and for assisting station maintenance. It allows for the investigation of a method whereby an acoustic event source size could be indicated as a magnitude estimate.