Integrated Tactical Monitoring of the 2014-2015 Eruption of Pico of Fogo, Cape Verde, by Spaceborne and Ground-based observations.

Abstract:

The 2014-2015 eruption of Pico of Fogo (Cape Verde), which totaled about 12 million cubic meters in two months, was monitored in real- and near-realtime by ground based and spaceborne instruments, respectively. Volcanic tremor amplitude (RSAM) above the background noise was first detected at seismic stations located at the foot of the Pico cone, about 08 UTC on November 23, 2014. A short-lasting, pre-eruptive tremor burst ca. 09:45 UTC forerun by about 1.5 hours the syn-eruptive tremor, which started between 11:12-11:15 UTC and was taken as the most reliable marker of the eruption onset. Spaceborne observation of MIR-TIR radiances with 15-minute refresh by payload SEVIRI onboard geostationary Meteosat-10, orbiting at 0°N-0°E over the Gulf of Guinea, pointed to a slightly later onset (11:15-11:30). Initial, radiant flux derived effusion rates were in the order of 16± 4 m³/s, with an isolated peak of 27 ± 8 m³/s reached on November 27, then slowly declined. RSAM and effusion rate series kept fairly well correlated in time, with tremor amplitude variations slightly ahead of radiance changes all the time. While villages located 1700m a.s.l. at the foot of Pico were largely destroyed by the early December, continued advance of lavas led to concern that the main flow could escape the summit caldera and propagate downslope to the northeast, threatening urban areas. Near-realtime monitoring of effusion rates became crucial to compute limiting flow lengths, and to assess that rates and volumes were not sufficient to sustain lava flow escapes. The 20 m³/s alert threshold was not approached anymore after December 9. Geophysical markers of sharply declined activity after mid-December, and until the end of eruption on February 7, 2015, could be constrained only by moderate-to-high spatial resolution data with multispectral pixel footprints between 10⁶ m² (MODIS) and 900 m2 (Landsat-8 OLI and EO-1 ALI)