Map Projections - Spatial Mathematics: Theory and Practice through Mapping - page 206

that is centered in the Pacific Ocean, the Pacific basin now becomes the
prominent feature on the map. As before, add the global natural hazards data
from NOAA/NGDC (NOAA/National Geophysical Data Center) and make the
significant earthquakes visible ( Figure 9.10b ) . Now, the earthquake pattern
around the Pacific rim comes to the fore. The homolosine was good for
looking at the interior of landmasses but was not good for looking at pat-
terns involving the land/ocean interface. Since the Eckert IV could be easily
centered on the 150 E meridian, and did not interrupt the Pacific Ocean, it
was vastly superior to the homolosine for visualizing earthquake pattern in
relation to the Pacific Ocean.
Go back to the group and open the map “Bonne_Projection” (a sample appears
on the title page of this topic). This map may be on the second page of the
Projected Base maps group. A Bonne projection is a pseudoconical equal-area
map projection that is memorable for its “heart” shape. The map may come
up showing only the oceans ( Figure 9.11a ) . As you did before, add the global
natural hazards data and make the significant earthquakes visible; but first,
add a layer showing the landmasses ( Figure 9.11b ) . How does this projec-
tion help you understand the global distribution and pattern of earthquakes?
Consider the location of earthquakes in relation to the tectonic plate bound-
aries, clearly visible in Figure 9.11a . The oceans are important, but aren't
other features just as important? Certainly they are in the case of studying the
relationship of the tectonic plate boundaries to earthquake location. In terms
of broad general context, however, the land/water interface offers enhanced
visualization!
As we have compared and contrasted several projections and consider their
merits and drawbacks for visualizing and understanding the earthquake data
at the global scale, so too we hope the reader will take this sort of critical
spatial analysis into other spatial realms.
9.10 Around the theoretical corner?
By now it should be clear from the discussions in this topic that there is
no perfect map. This is also one of the most interesting things about maps.
Maps may not be perfect, but they are incredibly useful. The myriad possible
map projections, each useful to somebody or some application, is a perfect
example of the utility of maps. There are thousands of different map projec-
tions and an infinite number more yet to be discovered. By the end of 2012,
for example, ArcGIS for Desktop software supported 4634 different map
projections. The number of map projections might appear a daunting pros-
pect; it is, however, a stimulating prospect! There is always something new
around the corner, yet to be discovered, in the wide world of mapping. Why,
one might ask, are there an infinite number of possible projections available?