No abstract

The Permanent Scatterers Synthetic Aperture Radar Interferometry (PSInSAR™) is a technique, which aims at ground deformation mapping with millimetric precision. In the framework of the Globvolcano ESA project, we evaluated a PSInSAR derived approach to monitor ground deformation in highly active volcanic areas, based on the example of Piton de La Fournaise. The Permanent Scatterer (PS) velocities show two main areas of deformation: (1) the eastern flank displaying old lava flow subsidence (0.05–0.13 m.y−1); and (2) the summit cone highly disturbed by eruptions. The PS time series for the summit area agree with the cGPS trends with small long‐term (weeks/months) ground displacements preceding eruptions (0.05–0.35 m.y−1) and large rapid ground displacements linked to eruptions. Despite some limitations, such as the loss of coherence during the most rapid ground displacements and lava flow emplacement, PSInSAR and its derived approach provide a reliable inference of the volcano ground deformation over large areas.

A refined ultrahigh-vacuum furnace for rare gas analysis

From south to north, the 4He/3He ratios of submarine basalts from the Red Sea and Gulf of Tadjoura increase from 45,000 (R/Ra=15) in the Gulf of Tadjoura to 84,000 (R/Ra=8.6) in the Mabahiss deep. Our helium isotopic results indicate that the mantle plume proposed in the north of the Red Sea, on the basis of the Sr and Pb isotopic ratios, does not posess a high 3He signature. The neon and Ar isotopic ratios of the Red Sea glasses are explained by mixing between AIR, MORB and a plume with a solar like isotopic Ne signature and low 4øAr/36Ar, similar to that of Loihi.