Volcanic Explosion in St Vincent and the Grenadines
Facebook Population Mobility Analysis from April 10th through 17th, 2021
On April 9th, 2021 the La Soufriere volcano in the north of the island of St. Vincent erupted, spewing heavy ash and smoke across the island and much of the surrounding region. An estimated 16,000 persons in the most heavily affected area were evacuated from the island and another estimated 2,000 persons left their homes. Throughout the next week the volcano has continued to erupt, with the largest such subsequent eruption occurring on the 17th of April.
Space-Time Population Hotspots Across St. Vincent and the Grenadines
Space-time hotspot analysis of population changes based on Facebook's Disaster Maps aggregated population data between April 10th and April 17th indicates the magnitude of the population reduction in northern St. Vincent, and the relative shift to southern communities.
(Symbology for space-time hotspot analysis)
Where were people moving away from and towards?
(Source: Facebook Data for Good)
Based on Facebook's data, the district of St. David, which is most proximate to the La Soufriere volcano, saw reductions of between 88% and 94% of people moving from the area, following the increase of greater that 200% on the 9th, which corresponds to the evacuation.
Despite the rapid depopulation of the north, the area as a whole registers as a sporadic rather than a persistent cold spot, with one very small exception on the coast. This means that day to day fluctuations in movement were still occurring throughout much of this area.
(Source: Facebook Data for Good)
Some of the sporadic nature of the cold spot is also related to activities specific to the relief effort. Whereas the St. David are saw an increase of nearly 500% movement relative to baseline to its southern neighbor in St. Patrick, St George also saw significant increases in population moving towards the most affected areas.
Persistent hot spots off the western coast are almost certainly attributable to ship-based relief, evacuation, and monitoring efforts.
In the southern-most portions of the country, where most people in St. Vincent live on normal days, every community has been a sporadic hotspot for the past week, which is likewise reflective of the rate of displacement from the volcano-affected areas.
St. Lucia, towards the north of St. Vincent shows no clear pattern of change in population density, although the large amount of water-based traffic off of the western coast is notable in terms of the proximity of ships which have been carrying passengers evacuated from St Vincent.
(Source: Associated Press)
For the most part the southern islands of the Grenadines have been far less affected overall, but a significant movement back and forth between the Grenadines and St. George was detected on Friday, April 16th.
(Source: Facebook Data for Good)
Emergency Shelters and Population Density Changes
The government of St Vincent has opened up 85 emergency shelters across the lower half of the island, which are intended to provide short-term resources for the large percentage of the population that may not be able to return home for some time. Each community is directed towards shelters in a particular area, in order to manage population influx, space, and resources.
Official St. Vincent government recommendation pathways for communities to access shelter resources.
While these recommendations for where communities may access shelter are crucial guides, there is no publicly available resource for tracking shelter occupancy, nor for estimating where shelters may be at risk of being over- or under-utilized.
By linking shelter locations with calculations from the Facebook population density mapping we can see where at least neighborhood population pressures on shelters may be most intense, where there may be need for greater or lesser numbers of open locations, and what if any areas may lie outside reasonable access requirements.
Shelters, bounded by a 1 km buffer and linked to average percentage change in population compared to baseline within 1 km of the location. (Source: St. Vincent government)
Based on this analysis, there is some level of concern warranted that shelters may be overly concentrated in the Kingstown area, as opposed to neighborhoods along the eastern shore. Population density is higher in Kingstown and areas to the northwest, but population change appears to be greater in neighborhoods to the east, even though they have fewer people at baseline.
Density of children under 5 and shelters relative to population change within 1 km of each shelter site in St Vincent (Sources: St. Vincent government and Facebook Data for Good)
Facebook data is limited to within country boundaries so the capacity remains limited at present to analyze distribution of refugee populations across neighboring islands. Long term displacement data, including disaggregation by gender, will become available as of April 23rd, and may prove to be useful not only in enhancing understanding of displacement within St. Vincent but also understanding dynamics and characteristics for those who have been displaced internationally.
