Geographer maps earthquake risk to population centres

The World Earthquake Intensity Map has been created on an equal-population map and allows users to understand the earthquake intensity in relation to today’s population distribution, giving an idea of where most people are at risk in regards to seismic activity.

It provides a visualisation of all major earthquakes that have been complied in the Global Significant Earthquake Database. The database contains information on destructive earthquakes from 2150 BC to the present day that meet at least one of the following criteria: moderate damage (approximately $1m or more), 10 or more deaths, magnitude 7.5 or greater, modified Mercalli intensity X or greater, or the earthquake generated a tsunami.

The map was created using these records by calculating ’kernel density’, an equation that shows the probability distribution of earthquakes, to visualise the areas most at risk from 2150 BC to the present day. The new earthquake map was then created by transforming the data in a way that highlights populated areas while eliminating depopulated regions.

The resulting map not only shows the areas that are at highest risk, but also how this risk relates to global population distribution.

The map was produced by Benjamin Hennig, a postgraduate researcher from Sheffield University’s Department of Geography, as part of his research into visualising the world.

In addition, Hennig, who has previously worked on an online atlas that used population rather than land mass to illustrate the size and shape of each country, has produced a new, more detailed population cartogram for Japan.

The cartogram shows the shape of the densely populated country and demonstrates that the majority of the urban population of 80m people are heavily concentrated on the Pacific shore of Honshū.

The cartogram also includes Japan’s topography and the surrounding ocean bathymetry (study of underwater depth of lake or ocean floors). The ocean floor played a crucial role in the development of the recent tsunami that hit Japan, which followed the earthquake, and caused much of the destruction on that densely populated Pacific shore.