People and Volcanoes: How many and how close?

Abstract:

Recent improvements in mapping human populations and development provide increasingly detailed perspectives on human settlement in proximity to potentially active volcanoes. Small and Naumann (2001) used a gridded compilation of census data circa 1990 to estimate that ~ 9% of the world’s population lived within 100 km of a historically active volcano and ~12% within a volcano believed to have been active during the Holocene. In this paper we update these estimates , using much more detailed census data circa 2010 from a preliminary release of the Gridded Population of the World version 4 (GPWv4) that will be distributed through NASA-SEDAC. Spatial analyses of these data in conjunction with the Holocene volcano database of Simkin and Siebert (1994) indicate that circa 2010 the estimated numbers of people living within 10 km (n=44,874,105), 50 km (n=443,637,182), and 100 km (n=853,108,062) of a volcano active within the Holocene period are larger than the estimates of Small and Naumann (2001). We attribute the higher recent estimates to improvements in the spatial resolution of GPWv4 compared to GPWv1 used in the earlier study. As we are not able to determine if the population in proximity to volcanoes has increased since 1990 using census data alone, we also use DMSP-OLS and VIIRS satellite observations of night light to quantify changes in lighted development in these areas. The new data provide considerably greater detail than those used by Small and Naumann (2001), though the global patterns do not differ significantly. While the quantified spatial relationships between global human population and recent volcanism can have both local and global utility, they may be most pertinent not as a global assessment of volcanic risk but as a comparative study of population distributions in volcanic environments.