DOPPLER SIGNALS FROM ROCKFALL

Rockfall seismicity is an indicator of shear lobe initiation and mass wasting from the dome to talus. Although seismicity correlates well with extrusion rate, there is no localised information to indicate rockfall direction. AVTIS 1 records bulk deformation over time, but changes from rockfall are difficult to detect directly. The radar uses Frequency Modulation to record the range to the surface, i.e. range is proportional to frequency, and any moving target within the radar beam will Doppler shift the reflected signal frequency and apparent range. AVTIS 2/3 will employ a Doppler imaging capability which decouples this range/velocity ambiguity and provides a direct mapping of rockfall activity indicating the location and strength of returns from falling blocks of lava.

AVTIS 1 scan illustrating Doppler signal

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