Ground deformation due to volcanic magma intrusion is recognised as an important precursor
of eruptive activity at a volcano. The Global Positioning System (GPS) is ideally suited for
this application. With the advent of inexpensive GPS receiver boards, the development of a
low-cost GPS-based volcano monitoring system is now possible. It provides an expendable
way of measuring volcanic activity.
This paper presents a novel, autonomous, deformation monitoring system based on the use of
the low-cost Novatel Superstar II receiver. The system uses several of those GPS units, one
of which being at a known reference location and the others being scattered around the area
of interest. The GPS Superstar II receivers provide measurements of the L1 carrier phase and
of the GPS ephemeris. Those measurements are logged at a user-defined sampling rate, and
transmitted via a radio link to a central processing station. The post-processing engine uses
those data in ambiguity resolution and baseline computation algorithms. The measurement of
changes in GPS baseline easting, northing and height components over time forms the basis
for measuring the volcano's expansion prior to eruption.
The paper reviews the major practical design considerations for GPS-based volcano
monitoring systems, together with the dominant error sources. The data processing steps
necessary to obtain the baseline between the reference receiver and each slave unit is also
detailed. The system validation is presented, showing the performance results obtained for
several baseline lengths, data sampling rates and observation session lengths. Each hardware
and software component is described, as well as the system architecture and the special
challenges in deploying and operating such a system in an inhospitable environment.
Craig Roberts, Cedric Seynat, Chris Rizos and Graeme Hooper. 3rd FIG Regional Conference Jakarta, Indonesia, October 3-7, 2004. Low-Cost Deformation Measurement System for Volcano Monitoring.