ABSTRACT
This chapter describes real-time ground deformation monitoring at Piton de la Foumaise using both electronic tiltmeters and automatic electronic distance meters. Periodic deformation of the ground surface is a common feature of active volcanoes, and is studied by means of traditional geodetic techniques such as precise levelling and trilateration. Both Banks et al. and D. Dzurisin discuss the potential pitfalls that can result from tiltmeter use for volcano monitoring, and Dzurisin offers sound advice on all aspects of tiltmeter acquisition, based on experience of extensive tiltmeter monitoring at Mount St Helens. Vertical ground deformation patterns associated with some recent intrusive and/or eruptive episodes at Piton de la Fournaise are described, including events that occurred prior to the establishment of the real-time processing system. The precise temporal identification of dyke emplacement during intrusive crises, using ground deformation monitoring, allows dyke migration velocities to be determined directly, both for the intrusive episode as a whole, and for individual phases during emplacement.
