Mapping the Threat of Active Volcanoes on a Global and Regional Scale

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Mapping the Threat of Active Volcanoes on a
Global and Regional Scale
Sakurajima volcano erupts, Kagoshima, Japan
Source Asianinfo.org

• Alex Samarin
• Dave Dixon

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Introduction

• Problem High population densities in regions of
  active volcanism produce a significant human
  threat
• During a large eruption, areas within 32
  kilometers are highly dangerous and areas within
  162 kilometers are still considered hazardous
• Some global regions are more at risk than others
• Based on population density, proximity to active
  volcanoes, recent volcanic history and proximity
  to the ocean, 3 regions have a higher risk of
  human loss
• Indonesia
• The Caribbean
• Japan

Volcano Deaths by Region 1600-1982
Blong, R.J. 1984
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Methods

• Since this is a geographic problem based on
  spatial relationships, the most effective way to
  visualize these data is to create thematic maps
  of each region
• Each map should include
• population density attributes people/square km
  in an unclassed choropleth map
• active volcano density attributes layer that
  includes point symbols on top of population
  density choropleth map

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Methods

• Population density attribute
• Number of people per square kilometer
• Lowest values (lowest density) visualized as
  yellow, highest density visualized as dark sienna
  brown
• Volcano attributes
• Actual locations represented as point symbols
• Hazardous area buffers
• 32 kilometer buffers around stratovolcanoes and
  complex volcanoes show areas in immediate danger
• 162 kilometer buffers show areas threatened by
  other implications of a violent eruption
• Highlight the most dangerous volcano(es) in each
  region
• Label and point out these features

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Maps Global

• Regions of study are highlighted by red boxes as
  a reference
• Only these three regions are labeled since there
  are no other relevant areas
• Issues
• Finding a suitable symbol to represent volcanoes
• Most were too heavy or to large (pop data was
  lost)
• Compromised with 3-point black dot symbol

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Maps Indonesia

• Choropleth population data shows that Indonesia
  is very densely inhabited
• Title is boxed and colored to balance the
  intensity of land areal features
• 32 kilometer buffer shows the extent of dangerous
  areas while transparent 162 kilometer buffer
  curtains the entire island of Java
• It becomes apparent that this region is the most
  susceptible to human loss from a violent eruption

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Maps Caribbean

• We readjusted certain map features to custom fit
  the land/ocean configuration, e.g. title box is
  shifted to upper right to balance weight of land
  cover
• Eastern islands below the title seem most at-risk
  since the 32 kilometer buffer consumes most of
  the land
• Included Ruiz, Columbia due to the ring of dense
  population around the volcano

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Maps Japan

• Decided to use portrait image layout due to the
  longitudinal orientation of island arc
• Potential threat of eruption is apparent
  especially in central-east coast near the
  historically deadly Oshima volcano
• Map elements (legend, title, scale bar) moved to
  the bottom
• Became an issue of space in the portrait layout
  but still balances activity above

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Conclusions

• Our cartographic techniques proved effective in
  visualizing the problem
• Shows that the imminent threat of a volcanic
  catastrophe exists over much of the worlds
  population
• Manipulating map elements and deciding on their
  most effective placement became a common yet
  interesting adversity
• May be possible with better data to consolidate
  all of this information into one map
• Could certainly be done in an interactive map,
  where 3D elevation models would greatly benefit
  visualization