A map, which provides a general representation of the risks of earthquakes on humanity using records from the past 4,000 years, has been produced by a geographer from the University of Sheffield.
The new World Earthquake Intensity Map has been created on an equal-population map and allows us 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 $1 million 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, in order to visualise the areas most at risk from 2150 BC to the present day. The earthquake map was then created by transforming the data in a way that highlights populated areas whilst eliminating depopulated regions.
The resulting map gives each person living on earth the same amount of space while also preserving the geographical reference. The map does not only show 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 the University’s Department of Geography, as part of his research into visualising the world in a new way.
In addition, Ben, who has previously worked on a new online atlas which 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 – 80 million people to be exact – 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 tsunami which followed the earthquake, and caused much of the destruction on that densely populated Pacific shore.
Benjamin, who is currently completing his PhD research and working on a book project on world population, due out in 2012, said: “The maps help us to get a better understanding of the relation between natural risks and global population patterns.
“Growing numbers of people live in highly vulnerable areas. The recent earthquakes in Japan and also in Christchurch are a tragic reminder of the fragile relationship between human livelihoods and natural hazards. New forms of visualisations can help to explain and better understand these relations from a human perspective.”