Cartografía de alta resolución y caracterización físico-química de los flujos de la lava de las fisuras 1, 2, 4 y 6 de la erupción de 2018 del volcán Sierra Negra: cartografía de alta resolución y caracterización físico-química de los flujos de la lava de las fisuras 2 y 6 de la erupción de 2018 del volcán Sierra Negra.

Abstract

June 2018 eruption of the Sierra Negra volcano located on Isabela Island, Galapagos, emitted lava flows through 6 eruptive fissures located on the northern and northwestern flank. In this work, part of the eruptive fissure 2 and 6 was mapped, locating elements of the lava field such as: internal contacts, levees, flow axis, outer edges and kipukas that allowed to deduce that there were at least two eruptive pulses during the period of activity of fissure 2. The estimate of the area of the lava field of fissure 2 was 8.32 ± 0.004 E+05 m2, the total volume (bulk) and DRE of the lava field resulted in 6.76 ± 0.65 E+05 m3 and 5.07 ± 0.49 E+05 m3 (assuming a percentage of empty spaces of 25%) respectively, and an average thickness for the entire lava field of 0.76 ± 0.71 m. The estimation of rheological parameters were made in a lava flow where an average viscosity value of 3.52 ± 0.2 E + 4 Pa s was calculated with an average speed of 0.10 ± 0.01 m/s that shows that the location of this lava flow could take at least 4 ± 0.2 hours. A minimum effusion rate of 4.4 ± 0.3 m3/s was estimated. And for the lava field, an effusion rate of 10-16 m3/s was estimated with an eruption duration time of 19 to 30 hours as reported (Calderón, 2022). The petrography and geochemistry of fissure 2 and 6 revealed a similar and restricted composition of pāhoehoe lavas and basaltic slags (%SiO2: 47.45-48.28), confirming that viscosity has not been affected by chemical changes.