Search

Satellite instruments play a valuable role in detecting, monitoring and characterising emissions of ash and gas into the atmosphere during volcanic eruptions. This study uses two satellite instruments, the Infrared Atmospheric Sounding Interferometer (IASI) and the Advanced Baseline Imager (ABI), to examine the plumes of ash and sulfur dioxide (SO 2) from the April 2021 eruption of La Soufrière, St Vincent. The frequent ABI data have been used to construct a 14 d chronology of a series of explosive events at La Soufrière, which is then complemented by measurements of SO 2 from IASI, which is able to track the plume as it is transported around the globe. A minimum of 35 eruptive events were identified using true, false and brightness temperature difference maps produced with the ABI data. The high temporal resolution images were used to identify the approximate start and end times, as well as the duration and characteristics of each event. From this analysis, four distinct phases within the 14 d eruption have been defined, each consisting of multiple explosive events with similar characteristics: (1) an initial explosive event, (2) a sustained event lasting over 9 h, (3) a pulsatory phase with 25 explosive events in a 65.3 h period and (4) a waning sequence of explosive events. It is likely that the multiple explosive events during the April 2021 eruption contributed to the highly complex plume structure that can be seen in the IASI measurements of the SO 2 column amounts and heights. The bulk of the SO 2 from the first three phases of the eruption was transported eastwards, which based on the wind direction at the volcano implies that the SO 2 was largely in the upper troposphere. Some of the SO 2 was carried to the south and west of the volcano, suggesting a smaller emission of the gas into the stratosphere, there being a shift in wind direction around the height of the tropopause. The retrieved SO 2 heights show that the plume had multiple layers but was largely concentrated between 13 and 19 km, with the majority of the SO 2 being located in the upper troposphere and around the height of the tropopause, with some emission into the stratosphere. An average e -folding time of 6.07±4.74 d was computed based on the IASI SO 2 results: similar to other tropical eruptions of this magnitude and height. The SO 2 was trackable for several weeks after the eruption and is shown to have circulated the globe, with parts of it reaching as far as 45 ∘ S and 45 ∘ N. Using the IASI SO 2 measurements, a time series of the total SO 2 mass loading was produced, with this peaking on 13 April (descending orbits) at 0.31±0.09 Tg. Converting these mass values to a temporally varying SO 2 flux demonstrated that the greatest emission occurred on 10 April with that measurement incorporating SO 2 from the second phase of the eruption (sustained emission) and the beginning of the pulsatory phase. The SO 2 flux is then shown to fall during the later stages of the eruption: suggesting a reduction in eruptive energy, something also reflected in ash height estimates obtained with the ABI instrument. A total SO 2 emission of 0.63±0.5 Tg of SO 2 has been derived, although due to limitations associated with the retrieval, particularly in the first few days after the eruption began, this, the retrieved column amounts and the total SO 2 mass on each day should be considered minimum estimates. There are a number of similarities between the 1979 and 2021 eruptions at La Soufrière, with both eruptions consisting of a series of explosive events with varied heights and including some emission into the stratosphere. These similarities highlight the importance of in-depth investigations into eruptions and the valuable contribution of satellite data for this purpose; as these studies aid in learning about a volcano's behaviour, which may allow for better preparation for future eruptive activity. [ABSTRACT FROM AUTHOR]

This paper uses volcanic eruptions on the Caribbean islands of Montserrat and Saint Vincent to explore the role that British colonial rule in the past and near past (1800–2000) has played in response to and recovery from hazardous events, and in turn, the influence that the nature of the hazards has on these responses. It shows that systemic vulnerabilities to natural hazards have been created by inadequate aid responses and longer‐term chronic problems and demonstrates that hazard impacts are compounded by them. Vulnerabilities could be reduced by analysing integrated hazard impacts to generate mitigative measures across hazards and identify actions that more closely match timescales of political decision‐making. Incorporating local knowledge and experience into risk analysis will enable the most effective use of aid resources, ahead of emergencies. Finally, coupling aid for long‐term development with emergency response would improve outcomes and adaptation to longer‐term vulnerabilities in immediate rebuilding and short‐term recovery. [ABSTRACT FROM AUTHOR]