A time series of magma flux measurements at the lava dome of Soufriere Hills Volcano, Montserrat

The lava dome that has been growing in the crater of Soufrière Hills Volcano, Montserrat since August 2005 is now visible above the crater rim. The dome poses increasing hazards of collapse and explosion due its size and the Montserrat Volcano Observatory (MVO) must assess these by observing the location and rates of dome growth. However, visual observations and conventional surveying methods cannot be used during the frequent periods when the dome is obscured by clouds. We propose, in collaboration with MVO, to measure, over a two week period, the shape and growth rate of the lava dome with the NERC-funded AVTIS (All-weather Volcano Topography Imaging Sensor) instrument which we built specifically to meet this need. In November 2005 we measured the dome with AVTIS from within the crater on two occasions. Now, without those logistical restrictions, we can measure the three dimensional surface of the lava dome using high resolution radar with this instrument at a rate of tens per day from sites outside the crater. These will reveal the way in which lava extrudes at the surface of the dome and the flux of magma into the dome changes over periods of hours to days and how these relate to the observable signals of gas flux and earthquakes. They may also show the conditions leading to a collapse of the dome. Such a detailed series of measurements have not been achieved before and we expect some exciting findings. In addition, we will make at least one measurement from within the crater to calculate the net growth rate since November 2005. This is the first opportunity anyone has had to make such detailed measurements of a growing lava dome with such an instrument and another opportunity may not present itself again for several years.