Proposed Programme

Studies of the physics and mechanisms of volcanic eruptions are not well advanced world-wide due to the rarity and brevity of eruptions and the danger to equipment from the volcano, the weather, and human interference. Yet they are essential if we are to reliably predict disastrous eruptions. Erebus offers a rare opportunity because it is continuously active, has a lava lake acting as a window to the magma chamber, is only mildly dangerous to equipment and personnel, and has no risk of water damage or human theft and destruction. Its situation in an aseismic region ensures that all the earthquakes have volcanic significance, and the relative lack of electronic and atmospheric pollution in Antarctica enable excellent telemetry of data and sampling of gas and heat output. The Antarctic Treaty has enabled International Cooperation and the sharing of costs and data to an extent which would have been next to impossible on most volcanoes. No other active alkaline volcano in the world can be studied so efficiently.

Thus our study of eruption mechanism is important world- wide, as well as because Erebus is a very large volcano of considerable importance for the understanding of the geodynamics and structure of Antarctica.

Our work has covered the distribution in space and time of volcanic earthquakes explosion earthquakes tectonic earthquakes, earthquake swarms and tremor, explosion infrasonic waves, magnetic induction signals from eruptions, infrared temperatures, eruption velocities and volumes of lava bombs, and the velocity structure of the erupting magma column. Also our TV surveillance has been of considerable help to S-081 (USAP) and to K092 in their studies of erupted gases.

The principal objectives of the season were to collect digital and video data on families of explosion earthquakes for the velocity modelling of the volcano and its magma column and to determine changes in the temperature of the crater walls and lava lake since 1986 and 1987.