On November 13, 1985 the eruption of Nevado del Ruiz in Tolima, Colombia triggered
lahars (mudslides) from the mountain's melting ice cap that swept down its slopes.
One destroyed Armero, killing more than 20,000 of about 29,000 inhabitants. There
were about 3,000 additional deaths in Chinchina and other towns. That was slightly
less deadly than the 1902 eruptions of Mount Pelee on Martinique. Usually, the deaths
on Martinqiue are estimated as 30,000 with Krakatoa (1883, Indonesia) accounting for
36,000 and Tambora (1815, Indonesia) in clear first place at 71,000.
Sometimes in mathematics it is of interest to normalize such numbers, otherwise
known as comparing percentages. During the period 1702-1711, at the request of the
King of Denmark (then ruling iceland), Árni Magnússon (1663-1730) conducted the
first complete census. Early on, the population had exceeded 50,000, but shrank under
35,000 by 1709 due to a lethal smallpox epidemic. There was another huge drop during
the period 1752-57. Then over an eight month period from late 1783 into 1784 the Laki
fissures and the Grímsvötn volcano poured out an estimated 15 cubic kilometers of
basalt lava and clouds of very nasty hydrofluoric acid and sulfur compounds
(estimated to be VEI=6). This killed more than half of Iceland's livestock population,
which, in turn, caused a famine that is generally held to have killed 10,000 people, or
about one fourth of the population. This was fewer people but a smaller percentage
than when the Bubonic Plague roared through Iceland during 1348-1351. Then as now,
the Icelandic volcanoes reached far beyond Iceland. During the summer of 1783 and
estimated 23,000 British people died from the poisonous gases that drifted south. The
winter was exceptionally cold, and another 8,000 deaths in England alone are
attributed
to Laki and Grímsvötn. It has become something of a contest to find ever larger effects at always longer distances. Besides a famine in Egypt in 1784, some give credit to Laki and Grímsvötn for the declines in French agricultural production that motivated the French Revolution.
The first problem a mathematician encounters in trying to answer did an eruption at
one volcano cause or suppress an eruption at another volcano is that the older data
gets the less precise years and effects become. Then there's the question of what exactly
an eruption is. After that there is the problem of how one volcano influences another.
Surely there are no volcanons to join the leptons and bosons, so there must be a
physical linkage. That would imply some sort of hyperbolic geodesic for the distance
metric. We have seen this before with earthquakes. Onward!