Mountains often are hidden in cloud. This can be particularly frustrating for volcanologists who want to observe the dynamics of activity at the tops of volcanoes. It also hinders their ability to develop new observational techniques for volcanic phenomena. Radiation at wavelengths much longer than visible light is much less affected by cloud. The microwave part of the spectrum allows us to "see" through cloud. Radar instruments achieve this by sending out pulses of radiation and receiving reflections back from the ground. The time this process takes allows the distance from instrument to ground to be measured.

In this project we use this principle in a new instrument that we have developed to view the tops of volcanoes. The AVTIS (All-weather Volcano Topography Imaging Sensor) instrument sends out pulses of radiation in the millimetre part of the spectrum (94 GHz) from which we can build up an image of the distance to the reflecting ground surface as in a radar. We are also able to capture the natural radiation from the ground that is a measure of the temperature. So the instrument is both a radar and a radiometer or radarometer.

We particularly want to use this new instrument to measure one of the most dangerous phenomena found at the tops of volcanoes - the growth of lava domes. These are large masses of viscous lava that pile up at the summit vent rather than flowing readily under gravity as ordinary lava flows. The reason they are so dangerous is that they can grow for a considerable time and then collapse suddenly producing immensely destructive pyroclastic flows that can travel many kilometres down the slopes of the volcano. Our understanding of how these lava domes grow, at what point they may become unstable and what triggers their eventual collapse is imperfect. One of the reasons for this is the lack of a way of observing and measuring the detailed growth of these lava domes, particularly when covered by cloud and at night. AVTIS will allow us to do that. However, it is not just a matter of getting new observations but of understanding the physical processes involved. So in parallel with instrument development the AVTIS project is developing a set of computer models of the way that the dome grows and becomes unstable. These will be used in conjunction with the new observations to help the volcanologists at observatories whose job it is to evaluate the hazard from the volcano.

We are testing this new technique at the Soufriere Hills Volcano on Montserrat, shown above. A lava dome has been growing there since 1995 and the pyroclastic flows from the dome flown down the valleys and have destroyed Plymouth, the main town of the island. Although the southern half of the island is evacuated, the Montserrat Volcano Observatory (MVO) still needs to advise government on the hazards posed by the ever-growing lava dome.

Our project began in October 2002 and is funded for three years by the Natural Environment Research Council of the U.K.. There are four partner organisations involved: The University of Reading, The University of St. Andrews, the University of Lancaster and the Montserrat Volcano Observatory. Hopefully we will have achieved sufficient progress at the end of the project to transfer the technology to the MVO as an operational method. The people involved are:

University of Reading - Environmental Systems Science Centre (ESSC)

Professor Geoff Wadge (project PI)

Miss Alina Hale - PhD student (modelling of lava dome growth)

University of St. Andrews - School of Physics and Astronomy

Dr. Jim Lesurf (Co-I)

Dr. Duncan Robertson (Photonics Innovation Centre)

Dr. Dave Macfarlane - PDRA

[Team responsible for the AVTIS instrument]

University of Lancaster - Environmental Sciences

Professor Harry Pinkerton (Co-I)

Miss Rhian Burrell - PhD student (modelling lava dome collapse)

Montserrat Volcano Observatory

Dr Peter Dunkley (Director, MVO)

Dr. Richard Herd

Dr Gill Norton

[Local liaison and operational testing]