Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN) reported that the eruption at Fernandina continued. The amount of lava flowing into the ocean significantly increased during 25-30 April and the lava flows spread along 800 m of the coastline. During 30 April-7 May daily thermal anomalies from the lava flow were identified in satellite images and gas-and-steam emissions rose from the area where lava entered the ocean. Sulfur dioxide emissions, measured using satellite data, fluctuated between about 205 and 803 tons per day during the first half of the week.

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)