Volcanic remote sensing measurements using Sentinel mission data and OP-FTIR.

Abstract

The increasing number of people living near volcanoes and the impending climate crisis calls for deepening our understanding on volcanic systems and magmatic processes. Volcanic eruptions constitute a geological hazard and a risk for those living in their vicinities. While the bigger risk usually is an imminent eruption, daily exposure to volcanic gases can have a significant effect on people’s health, leading to an increase in respiratory diseases, and lower- ing the quality of living. In the last decades, the use of different remote sensing instruments have proven very successful to monitor volcanic systems, as well as to collect data from a safe distance during eruptive events. UV and IR spectrometers have become increasingly popular for their efficacy in detecting and quantifying volcanic gases that allow for monitoring and deepening our understanding on magmatic processes prior and during eruptive events. Application of remote sensing methods becomes more relevant and a key part of volcano monitoring when the volcanic system is located in difficult to access locations. An example of this types of volcanic system is presented in this thesis through the work done for Nyi- ragongo volcano, combining different types of satellite imagery. Nyiragongo is located in the Democratic Republic of Congo (DRC), in the middle of a rainforest, with a very compli- cated political and health context. Furthermore, several issues related to funding of the local observatory, as well as stolen instrumentation has occurred during the last decade. There- fore, applying satellite imagery to measure and quantify changes in the degassing and lava lake level, have proven very relevant. Here I present two different works using TROPOMI SO2 imagery. In the first one we have combined our datasets with an already published SAR imagery study, linking the lava level changes with the degassing patterns. In both cases, we used a relatively novel technique to retrieve injection times and altitudes, to quantify the total degassing for a period of time, as well as for the eruptive episode that took place on May 22nd, 2021. Our results and pro- posed mechanisms to explain the lava lake drops linked with degassing spikes, could be used to better understand the lack of degassing precursory signal before the fissure eruptions of Nyiragongo. The application of remote sensing methods such as open-path Fourier transform infrared spectroscopy (OP-FTIR) is a powerful approach to study magmatic processes during erup- tions. Collecting nearly daily data through the La Palma, Canary Islands 2021 an 85 days eruptive event, provides a unique insight into the evolution of the eruption through investi- gating the changes in the ratios of magmatic gas compositions. Furthermore, this eruption also represents a clear example of the influence that magma oxidation have in volatile solu- bility. The methods and data used in this thesis can help to improve the understanding of different volcanic systems and its particular magmatic systems, helping to improve eruption prediction in the case of Nyiragongo, and eruption development in the case of similar magmatic system as the Canary Islands.

Date of Award	1 Aug 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Catherine Hayer (Supervisor) & Mike Burton (Supervisor)