Saturday, July 7, 2012
A data visualization company compiled this global map of magnitude 4 and greater earthquakes recorded since 1898; over 200,000 of them. The map is centered over the Pacific Ocean and quite clearly illustrates the ring-of-fire seismic zones surrounding the ocean basin, especially highlighting the subduction zone areas in the western Pacific. Subduction zones where two tectonic plates are colliding and one plate dives under the other creating the planet's largest, most violent earthquakes (why Alaska, Japan and Indonesia are so often in the geologic news).
Other fascinating features are the Hawaiian Islands volcanic hotspot - that light cluster in the otherwise dark mid-Pacific, and the north-to-south wavy outline of the mid-Atlantic ridge along the far right border. The mid-Atlantic ridge is an area of plate creation and spreading of materials east and west – a less violent activity than subduction so with corresponding “milder” seismic activity.
While this map is simply a visual representation of data, its net effect can be a much more powerful on our imaginations than mere tables or columns of data can possibly be. Such visualization techniques aid in big-picture thinking – the ability to take lots of individual data points and imagine and then study the natural processes they represent. The printed media is no stranger to this technique of course. In my early days of budding interest in oceanography, National Geographic published their mapped representation of the oceans’ bathymetry. Especially startling was the pronounced mid-Atlantic Ridge feature. Of course the vertical scale (relief) was over-represented for creating a visual effect, but the purpose was to illustrate data and stir the imagination. It had that effect on me and helped spur a love of maps, including those for underwater topography. In later research years I would spend hours on lakes and rivers mapping bathymetric contours and study submerged features on the Grand Banks and off the coastlines of maritime Canada and New England. There’s another world down under that is sometimes hard to fathom.