Benjamin Bernard, Michael J. Stock, Diego Coppola, Silvana Hidalgo, Marco Bagnardi , Sally Gibson , Stephen Hernandez, Patricio Ramón, Matthew Lloyd Morgan Gleeson 

The 1982 and 2015 eruptions are the first at Wolf volcano, Galápagos Archipelago, with eyewitness accounts and satellite imagery. Both eruptions are characterized by a rapid, intense initial phase and multiple eruptive vents leading to the formation of large ‘a‘ā lava fields with scarce pāhoehoe deposits, mostly associated with the waning phases. The 1982 eruption started on 28 August from an intra-caldera vent that produced high lava fountaining, but also occurred from a radial fissure on the SE flank. This eruption lasted for at least 9 days and generated approximately 70E+6 m3 of lava. The 2015 eruption started on 25 May from a circumferential fissure that also produced high lava fountaining and deposited reticulite scoria on the flanks of the volcano. For the first time since monitoring Galápagos eruptions, we observed cryptotephra from the 2015 eruption reaching and depositing in mainland Ecuador, 1400 km away from the source. Lava from the 2015 circumferential vents covered large areas on the SE and E flanks. On 13 June 2015 the eruption switched to an intra-caldera vent that was active until 30 June, which produced lava flows that covered most of the caldera floor. This eruption lasted 36 days and produced ~116E+6 m3 of lava, making it one of the largest eruptions in the Galápagos since the eruption of Sierra Negra in 1979. The combination of ground-based geophysical surveillance, remote sensing, eyewitness accounts, and detailed field work allows us, for the first time, to constrain the eruptive dynamics of this remote volcano with a day-by-day time resolution. In particular, our approach allows quantification of eruption rates, which represents critical information for understanding volcanic systems and for hazard assessment. First order rheological calculations further enable us to constrain the eruption dynamics and emplacement of the lava fields.