First testing of a volcano Doppler radar (Voldorad) at Mount Etna, Italy

International audienceA medium-power (1 kW) Doppler radar of limited weight (110 kg) and working in the UHF band has been developed for active remote sensing of volcanic eruptions. Named Voldorad, this radar is designed to monitor eruptive activities of variable magnitude at medium distance range (-0.5-5 km), in any weather condition, and fills the gap between low-and high-power radar or sodar systems previously tested on volcanoes. Voldorad was operated for the first time during an eruption of Mr. Etna on October 11-12, 19911. Doppler spectra recorded at 1 km distance from the vent reveal powerful echoes during the eruption paroxysm (lava fountains), which gradually decreased along with declining activity. An average vertical velocity of 110-117 m s 4 is inferred for the eruptive jets. by Hort and Sey•ied [1998] and Sey•ied and Hort [1999] is more promising. The first tests were conducted 200-300 m away from the vent, but the operating range could be increased by using a parabolic mirror antenna with a small aperture [Seyfried and Hort, 1999]. Based on the [JHF wind profiler technique [e.g. Ecklund et al., 1990], we have developed and tested a medium-power pulsed Doppler radar specifically devoted to volcanic sounding [Dubosclard et al., 1999]. Named Voldorad, this radar can operate at medium distance (-0.5 to 5 km) from a volcanic vent and is compact enough to be easily set up on a volcano. In the following, we describe this new insreinvent and report preliminary data recorded during an eruptive sequence of Mount Etna (Sicily) in October 1998