IG-EPN reported that the eruption at Fernandina continued during 6-12 March from a circumferential fissure located on the upper SE flank, though gradually decreased during the week. Hundreds of thermal anomalies over the lava flows were identified daily in satellite images during 5-8 March, and the longest lava flow advanced 100 m to a total length of 8 km. Gas emissions associated with the emplacement of lava flows drifted WSW. A fire W of the flow field was observed on 7 March. During 8-11 March dozens of thermal anomalies were identified daily in satellite images. Sulfur dioxide emissions measured from satellite were variable, with measurements between about 1,870 and 4,160 tons per day during 7-10 March.

Geological Summary. Fernandina, the most active of Galápagos volcanoes and the one closest to the Galápagos mantle plume, is a basaltic shield volcano with a deep 5 x 6.5 km summit caldera. The volcano displays the classic "overturned soup bowl" profile of Galápagos shield volcanoes. Its caldera is elongated in a NW-SE direction and formed during several episodes of collapse. Circumferential fissures surround the caldera and were instrumental in growth of the volcano. Reporting has been poor in this uninhabited western end of the archipelago, and even a 1981 eruption was not witnessed at the time. In 1968 the caldera floor dropped 350 m following a major explosive eruption. Subsequent eruptions, mostly from vents located on or near the caldera boundary faults, have produced lava flows inside the caldera as well as those in 1995 that reached the coast from a SW-flank vent. Collapse of a nearly 1 km3 section of the east caldera wall during an eruption in 1988 produced a debris-avalanche deposit that covered much of the caldera floor and absorbed the caldera lake.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)