A new study, led by the European Commission’s Joint Research Centre (JRC), characterizes in unprecedented detail the changes in the last 40 years in the distribution of global human population living in proximity to historically active volcanoes.
Moderate to large volcanic eruptions are infrequent but potentially high-impact incidents, especially for nearby populations due to lava flows, ash deposition, “pyroclastic” events, etc. As was shown by the 2010 eruption of Iceland’s Eyjafjallajökull volcano even modest eruptions in relatively remote locations can have global impacts. In densely populated areas, small to moderate eruptions may constitute severe threats, generating multiple hazards affecting areas from the immediate vicinity to hundreds of kilometres away.
Volcanic activity remains a constant threat globally and the number of people at risk from volcanism is rising with increased urbanization and population growth. However, volcanic risk analysis and assessment at the global scale is not as advanced as for other hazards such as flooding, earthquakes and tropical cyclones, being limited by the availability and quality of data, especially regarding consistency and detail.
Similarly to earthquakes, volcanic eruptions are difficult to mitigate technologically, as the hazard component can hardly be decreased by human action. While expected global losses may be less than those from other hazards, in affected regions they can be very significant. Since 1950, on average 31 volcanoes have erupted each year, and at any one time at least 20 are erupting. Thus, major gains to disaster risk reduction are to be obtained by reducing vulnerability and especially exposure, requiring improved assessments of these components.
In the JRC-led study, the worldwide distribution of population from 1975 to 2015 was assessed and characterized in relation to recent volcanism, using the best available global population grids - i.e. the global population distribution grids for 1975, 1990, 2000, and 2015, produced by the European Commission’s Global Human Settlement Layer project - together with two widely used global databases of the latest information on volcanoes: the Holocene Volcano List of the Smithsonian Institution’s Global Volcanism Program, and NOAA’s Global Significant Volcanic Eruptions Database. The latter two datasets include 1,426 volcanoes with eruptions in the Holocene period (approximately the last 10,000 years, beginning after the last glacial period), and those where there is evidence of significant eruptions.
Results of the study show that in 2015 over 8% of the world population lived within 100 km of a volcano with at least one significant eruption, and 14.3% (over 1 billion people) lived within 100 km of a Holocene volcano, with human concentrations in this zone increasing since 1975 above the global population growth rate. While overall spatial patterns of population density have been quite stable in time, they have varied with distance, with a higher concentration of people within 10-20 km from volcanoes. (See Figure below).
A comparative analysis conducted for the volcanic hot spots of Southeast Asia and Central America also shows that in the last 40 years, in Southeast Asia the highest population growth rates have occurred in close proximity to volcanoes (within 10 km), whereas in Central America these are observed farther away (over 50 km), especially after 1990 and for Holocene volcanoes.
The JRC study on changes in the proximity of global population to volcanoes (full details of which are at the web-link below) demonstrates how emerging open and free geospatial datasets can narrow gaps in population distribution data and knowledge, supporting disaster risk management and reduction activities.
European Commission, Joint Research Centre (JRC)
For more information:
Freire, S., A.J. Florczyk, M. Pesaresi and R. Sliuzas. 2019. An Improved Global Analysis of Population Distribution in Proximity to Active Volcanoes, 1975–2015. International Journal of Geo-Information, Vol. 8, Issue 8, 341. www.doi.org/10.3390/ijgi8080341