IFE14 Inspection Techniques

The Treaty defines specific activities and techniques that can be applied during an on-site inspection (OSI), starting with less intrusive and moving to more intrusive techniques. In IFE14, the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) will practise almost all Treaty-permitted techniques, which is substantial progress on the 2008 Integrated Field Exercise (IFE08), as shown below:



Techniques Tested in IFE08 and Available for IFE14




Visual observation

Visual observation helps the inspection team narrow down the inspection area or identify specific inspection activities that may be warranted. Observations from both the ground and the air take place and findings are recorded with digital still and video photography.


Multi-spectral imaging

Multi-spectral imaging measures light at wavelengths around the spectra of visible light. The resulting images are then combined and may provide additional information about changes in surface, near-surface and sub-surface features.


Air-borne gamma spectroscopy

Air-borne gamma spectroscopy is used during additional overflights as well as during ground based surveys, and helps identify elevated levels of gamma radiation which may have been caused by geological phenomena but also by man-made activities and may thus point to a possible nuclear explosion. 


Gamma radiation monitoring

Gamma radiation monitoring helps identify gamma radiation that appears to be anomalous against the natural radiation background and so helps select regions within the inspection area for detailed investigation.


Environmental sampling

Environmental sampling involves the inspection team collecting samples, such as air, soil, vegetation and water, for analysis in a specialized laboratory.



Measurement of argon-37 and radioxenon

Argon-37 and radioxenon (radionuclides relevant for an on-site inspection) are measured in the field using mobile equipment.



Seismological monitoring of aftershocks

Seismological monitoring of aftershocks measures minute seismic events with distinct seismic signatures that typically occur following a large underground nuclear explosion.



Magnetic field mapping

Magnetic field mapping measures deviations in the Earth’s magnetic fields that can be caused by different iron-containing objects in the ground. The presence of such objects can point to infrastructure elements of an underground nuclear explosion, such as pipes, cables or shafts.


Gravitational field mapping

Gravitational field mapping looks for changes in the density of the rock and can help locate the cavity created by an underground nuclear explosion.



Electrical conductivity measurements

Electrical conductivity measurements can help identify metallic objects near the surface that may belong to the infrastructure of a possible nuclear explosion. Deeper measurements will lead the inspectors to identify disturbances in the underground geological structures, such as cavities or changes in the water table, which, in both cases, may result from an underground nuclear explosion.


Active seismic surveys

Active seismic surveys create shock waves artificially which are then measured to identify changes and disturbances in the underground geological structures.



Resonance seismometry

Resonance seismometry measures underground seismic tremors which can help to identify underground cavities.




Drilling involves obtaining samples from the actual site of the suspected explosion and therefore potentially carries great health risks. The inspectors must request authorization from the Executive Council to drill in the inspection area.