ANNEX 2 TO THE PROTOCOL

List of Characterization Parameters for International Data Centre Standard Event Screening

1. The International Data Centre standard event screening criteria shall be based on the standard event characterization parameters determined during the combined processing of data from all the monitoring technologies in the International Monitoring System. Standard event screening shall make use of both global and supplementary screening criteria to take account of regional variations where applicable.

2. For events detected by the International Monitoring System seismic component, the following parameters, inter alia, may be used:

- location of the event;

- depth of the event;

- ratio of the magnitude of surface waves to body waves;

- signal frequency content;

- spectral ratios of phases;

- spectral scalloping;

- first motion of the P-wave;

- focal mechanism;

- relative excitation of seismic phases;

- comparative measures to other events and groups of events; and

- regional discriminants where applicable.

3. For events detected by the International Monitoring System hydroacoustic component, the following parameters, inter alia, may be used:

- signal frequency content including corner frequency, wide-band energy, and mean centre frequency and bandwidth;

- frequency-dependent duration of signals;

- spectral ratio; and

- indications of bubble-pulse signals and bubble-pulse delay.

4. For events detected by the International Monitoring System infrasound component, the following parameters, inter alia, may be used:

- signal frequency content and dispersion;

- signal duration; and

- peak amplitude.

5. For events detected by the International Monitoring System radionuclide component, the following parameters, inter alia, may be used:

- concentration of background natural and man-made radionuclides;

- concentration of specific fission and activation products outside normal observations; and

- ratios of one specific fission and activation product to another.