Application of DOAS for Studies of Evolving Volcanic Activity in Central America

Abstract: Volcanic gas emissions play a critical role in understanding the physical processes that drive eruptive activity. Combining gas measurements with other geophysical parameters provides a more accurate description of the changes that occur beneath a volcano. Understanding and tracking the evolution of volcanic activity is crucial for populated areas that may be affected by a potential eruptive crisis.This thesis illustrates the application of ground-based optical remote sensing using Differential Optical Absorption Spectroscopy (DOAS) for measuring volcanic gas emissions. Some measurements have been made within a range of several days to a few weeks, while in some cases we made measurements for more than one year. The case studies include the following volcanoes: Turrialba (Costa Rica), Concepción (Nicaragua), Arenal (Costa Rica), and Télica (Nicaragua).At Turrialba volcano the measured SO2 flux emissions clearly indicated an imminent eruptive event. The volcano’s degassing evolution during different periods was extensively compared with the most relevant seismic signatures. At Concepción volcano our measurements were related to seismic and geodesic indicators during an active eruptive period and a quiescent period. Preliminary results of ongoing measurements at Télica and Arenal volcano are also reported.Different comparisons in different scenarios provide multi-parametric surveillance methods that may be adopted by local institutions in charge of dealing with volcanic risk assessment.