Resumen:
The back-arc (Eastern sub-Andean belt) of the Ecuadorian Andes encompass four volcanoes:
Reventador, Yanaurco, Pan de Azúcar, and Sumaco. Despite the proximity of these volcanoes,
Sumaco volcanic materials are distinctly SiO2-undersaturated alkalines. Through seismic travel
time tomography, three velocity models (𝜐𝑃, ∆𝜐𝑃, 𝜐𝑃/𝜐𝑆
) were generated to identify the
primary magmatic reservoir of the Ecuadorian back-arc. The inverse problem was solved using
the INSIGHT computer code package in a gridded parallelepiped box with a cell size of 5 km in
the horizontal direction and 2 km in the vertical direction. This study finds the principal
magmatic chamber located below the Sumaco volcano but slightly shared with the extinct Pan
de Azúcar and Yanaurco volcanoes.
Sumaco Fault extension is also recognizable and is expected to be responsible for the rapid
ascent of the magma towards the surface before an eruption.
As a conclusion, a significant factor that could lead to the differentiation of the Sumaco lavas
is a hypothetical flat slab block below the volcano
