In your professional opinion, which volcano provides the greatest
risk to people at the moment?
I am asking on behalf of a friend who would like to do a special study
of the volcanic hazard.
Chris Durbin
Hi Chris,
That is another difficult question, and one that volcanologists are likely
to disagree on. You might want first to think about the difference
between "hazard" and "risk". Hazard refers to the actual things that a
volcano can do (produce ash, lava flows, pyroclastic flows, cause
earthquakes, etc.) and how often or likely these events are. Risk adds
the human element to the picture, namely, what damage are the ash, flows,
quakes etc. likely to do to humans and things that humans care about. For
example, there is a large volcanic hazard on the Galapagos island volcano
of Fernandina. It erupts relatively frequently, its lava flows travel
swiftly down the slopes, and it has been known to be explosive. But,
since nobody lives there the risk--at least the human risk--is negligable.
Of course if you care about iguanas and Galapagos Hawks it is another story.
So, in your quest to find the most dangerous volcano you need one with a
high geological potential to produce dangerous products and events as well
as a large nearby human population. There are many candidates: Vesuvius
(Italy)
erupts in a violent way and many many people live on its flanks. On the
other hand it is in a relatively developed country with a long history of
volcanic studies, which reduces the risk somewhat. Colima (Mexico) is
another dangerous volcano. It has steep slopes, produces fast-moving and
relatively common pyroclastic flows, and is also prone to huge avalanches.
There is the beautiful city of Colima at its base so there are many
people at risk. Colima is monitored pretty closely. Nevado del Ruiz
(Colombia) has proven itself to be quite deadly. It is very high and has
a permanent snow cap at the summit. Even small eruptions can melt aa
permanent snow cap at the summit. Even small eruptions can melt a
great deal of this snow to cause fast-moving lahars. Additionally, Colombia
seems to always be suffering through some sort of internal turmoil, which
can't be good for the valiant monitoring and public-education efforts of
its few volcanologists.
I haven't exactly answered your question, but hopefully your friend will
be able to take some of this information with him or her on the trip to
the library. Get out a map of some volcanic eruption and see how many
towns are on the flanks. Are there many? Are there sufficient roads to
evacuate people on? Is it a developed country? Is it an open society
where the government is willing to notify the population even about
negative things? All these would go into a good report about the
potential risk of any volcano.
Sincerely,
Scott Rowland
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