Saturday, January 05, 2013

Proximity to peril


While researching for a story set in the aftermath of a super volcano eruption, I came across some photos that drive home how tens of million human beings live in close proximity to some of the planet's more powerful volcanoes.

Below, Japan's Aso caldera. While not quite a full-fledged "super volcano" in terms of ash output, this volcano has covered much of Japan with heavy ashfalls and superheated pyroclastic flows. Presently it's home to croplands, several towns, and a small city, as well as complex of active volcanoes in at its center.

Photo courtesy of NASA, public domain


Not far to the south is the Aira caldera. Aira has generated VEI7 (Volcanic Explosivity Index 7) eruptions with an ash output greater than one hundred cubic kilometers of ash. That qualifies it as a super volcano, under the commonly used, if unofficial, definition of VEI7 or greater. The northernmost slice of the caldera is occupied by the city of Kagoshima, which contends with periodic ashfalls from the caldera's central volcanic peak, Sakurajima.

Photo courtesy of NASA, public domain



Then there is Italy's famous Mt. Vesuvius, of Pompeii fame. Several million people live in close proximity to the volcano. This includes the citizens of Naples, which is effectively sandwiched between Vesuvius and massive Campi Filigri caldera. Campi may have depopulated much of Southern and Eastern Europe during a massive ash eruption around 35,000 years ago, sending the Neanderthal populations of those areas and the near Middle East into terminal decline, and clearing the way for the entrance of modern humans onto the continent after being held at bay for 10,000 or more years.

Photo courtesy of NASA, public domain


Campi Filigri below. The caldera is difficult to make out, but it encompasses most of the bay toward the bottom center, and a noticeable slice of the coastline, including the city of Pozzuli. The city of 40,000 was temporarily evacuated during the early 80s, when the caldera floor uplifted during a period of swelling by over a meter.

Photo courtesy of NASA, public domain



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