GASPAR, J.L., QUEIROZ, G., PACHECO, J.M., FERREIRA, T., WALLENSTEIN, N., ALMEIDA, M.H., COUTINHO, R. (2003) - Basaltic lava balloons produced during the 1998-2001 Serreta Submarine Ridge eruption (Azores). In: Subaqueous Explosive Volcanism, White, J., Clague, D., Smellie, J. (Eds.), American Geophysical Union, Geophysical Monograph 140, 205-212.​

​In December 1998 a volcanic eruption started about 10 km W of Terceira Island, Azores, on the so-called Terceira Rift. The eruptive vents were located in the Serreta Submarine Ridge, at depths ranging from 300 to 1000 meters. The observed eruption was preceded by a small seismic crisis, and lasted for more than two years. The tectonic setting of the eruption site, the alignment of the eruptive vents and the type of volcanic products point towards a basaltic fissure eruption. The most striking features formed during this eruption were “lava balloons”. These hollow structures, spherical to ellipsoidal in shape, are interpreted as the result of puffing up of gas under the plastic surface of lava at vent level. Degassing of a very fluid, gas-rich magma within or beneath submarine lava lakes and/or during lava fountaining episodes is believed to be the process that generates such structures.