Earthquake risk zones: A people’s perspective

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A M7.8 earthquake has occurred in Nepal “as the result of thrust faulting on or near the main frontal thrust between the subducting India plate and the overriding Eurasia plate to the north.” As the USGS summarises, “although a major plate boundary with a history of large-to-great sized earthquakes, large earthquakes on the Himalayan thrust are rare in the documented historical era. Just four events of M6 or larger have occurred within 250 km of the April 25, 2015 earthquake over the past century”.
In a paper for the Journal of Maps published in 2014 I have analysed and visualised data documenting earthquakes that have occurred since 2150 BC. The following map was part of the material supplementing the publication showing the results of the analysis shown on an equal population projection. The gridded cartogram gives every person on the planet an equal amount of space while highlighting the most densely populated spaces in relation to the earthquake risk (calculated via the intensity of earthquakes recorded since 2150 BC). Also shown are the world’s megacities (over 5 million population). The map shows the large populations that make even Nepal (with its almost 28 million people) much more visible than it would be on a conventional map, highlighting why this event turns out to be quite disastrous. The map also shows what the USGS statement above mentions that Nepal is amongst the areas in the region which are far less subject to major earthquakes (as indicated by the yellow to blue shading in the map there – Nepal is the rather large spot squeezed on top between the areas that represent the large populations of India and China):

Map of earthquake risk zones on an equal-population projection
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Volcanoes and Human Population

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The Calbuco volcano in southern Chile erupted for the first time in more than five decades, which in the global media was covered more for its visual spectacle rather than its perception as a major catastrophe. This can be partly explained with the low threat that Calbuco poses to larger numbers of people. As reported by the BBC, “authorities have declared a red alert and evacuated more than 4,000 people within a 20km (12 mile) radius”. This is a relatively low number as the volcano is situated in a sparsely populated, mountainous area. Natural events usually turn into natural disasters when they happen in more densely populated areas. The following map shows how human settlement patterns and the global distribution of volcanoes correlate by drawing a 100km radius around each of the world’s volcanoes and then projecting this data onto a gridded population cartogram. This equal-population projection results in some of these 100km risk zones around the volcanoes to become hugely visible, because there are large populations living in this area, while other volcanoes and their risk-radius become almost invisible due to the low number of people living there. Very often, these are the decisive differences between a volcanic eruption being a natural event (or even spectacle) and a natural disaster, which these events can become in the red-shaded areas of this map:

Map of volcanic risk zones on an equal-population projection
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Healthy Soils for a Healthy Life

International Year of SoilsHealthy Soils for a Healthy Life is the motto of the UN International Year of Soils which aims to “increase awareness and understanding of the importance of soil for food security and essential ecosystem functions.” As explained on the campaign’s website, “soil is the thin layer of material on the Earth’s surface. It is a natural resource consisting of weathered and organic materials, air and water. As it is the medium in which plants establish themselves and grow, the most widely recognized function of soil is its support for food production. Soil provides nutrients and water that are absorbed through plant roots and contribute to the regulation of water and atmospheric gases and therefore play an important role in climate regulation.”
Soil therefore matters most where is is near human population, which at the same time puts soils under extreme pressure in these areas. Soil types not least determine where humans used to settle when they gave up their nomadic lifestyles and started becoming more stationary as farmers. Nowadays, some of the most fertile soils are found in the most densely populated spaces on the planet, which is shown in the following map. The map shows the major soil types classified in the FAO/UNESCO Soil Map of the World reprojected on a gridded population cartogram where a grid is resized to give every person living within a grid cell an equal amount of space (reducing the map in those spaces most where there are fewest people):

Map of major soil groups
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Water worlds: Ocean Chlorophyll levels

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The ocean is the last frontier that has not been discovered by cartogram techniques before. As such, it was an inevitable step in my PhD research some years ago to test the creation of a gridded ocean cartogram, a cartogram that is limited to the extent of the world’s oceans (also linking nicely to my past research on coastal ecosystems).
Chlorophyll concentrations in the world’s oceans are important indicators for the presence of algae and other plant-like organisms that carry out photosynthesis. As such, phytoplankton (which contains the chlorophyll) is an essential element of the food chain in the seas as it provides the food for numerous animals. Variations and changes in the chlorophyll levels are also relevant for the study of the ecology of the sea. Changing chlorophyll levels can indicate changing sea temperatures and other conditions in the oceans that cover about 72 percent of the planet’s surface.

Gridded cartogram visualisation of Ocean Chlorophyll concentrations
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Hyperspectral remote sensing and analysis of intertidal zones: A contribution to monitor coastal biodiversity

The growing amount of remotely sensed data and the ongoing developments in the improvement of spatial and spectral resolutions lead to high expectations. These often inflated expectations are usually not fulfilled. I explored these expectations and aimed to make a contribution to bring them to a more accurate level in research in the field of hyperspectral image analysis of small scale and heterogeneous biotopes in the intertidal zones of coastal areas which I undertook back at my time at the University of Cologne and the Alfred Wegener Institute for Polar and Marine Research Bremerhaven. Here are some insights from my work.

Map overview of the Study Areas on Helgoland and Sylt
Overview of the study area on the islands of Helgoland and Sylt, Germany
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Global tree cover

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There is a long tradition in the emotional relationship between people and forests. We can get an understanding of the extent of the global tree cover from satellite sensors such as NASA’s MODIS
Calculating the average tree cover in an area allows us to estimate the extent of the world’s forests. Forest landscapes can be mapped in various ways and is often done in conventional maps. However, much of the land area is not covered by forest and the few remaining untouched forest landscapes keep shrinking while deforestation continues.

Gridded cartogram visualisation of global tree cover
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