PART 3. Igloos
and sugar mills: how to survive pyroclastic surges on Montserrat and elsewhere
never expected to be recommending igloos for Montserrat residents! But
this ancient design, easily recreated in reinforced concrete, is perfect
for sheltering from hurricane-force winds and surges. You site the
entrance facing downwind and fit (on Montserrat) an airtight door
insulated with something like felt.
shows precisely what
to do. The underground cave could be sealed for weeks by hot ashes (or
one is crude but perfectly sited on a slope.
optional as to how you equip your concrete igloo!
Do we have to look very far to find
igloo-like potential surge refuges on Montserrat? The answer is clearly
judging from the following images. The island is dotted with the small conical
mills that extracted the juice from sugar cane. These sturdy buildings look a
bit like igloos and clearly are extremely resistant to both pyroclastic surges
and even the actual PFs.
|I'm surprised that
oast house owner from Kent, UK, has
bought one of these for their Caribbean hideaway!
|Maybe Bob Dylan
will someday buy this one and all the valley for his ultimate secluded
place. Of course National Park status is a problem (not that such trivia
worry a rich Brazilian friend of mine!).
in impossible places and make useful scales.
Our ancestors were obsessed with the need
to make impregnable dry-stone forts to hide in. As early as at least 3000-4000
years BC they discovered that the conical "sugar mill" design was ideal.
By about 2000 BC,
people of Sardinia had dotted the island with these small forts. I have
a local tourist leaflet that calls them the
Picts in Scotland built fine examples
and called them brochs.
To make a
vitrified fort, you fill the structure
with wood and ignite it. The raging fire melts a thin layer of the
stone, giving you an exceptionally strong fort (or surge shelter on
Modern concrete buildings in Brazil show
how easy it would be to use this flexible material to build surge-proof shelters
on Montserrat. It is not necessarily a pre-requisite that such shelters should
be either artistic or viewed only by moonlight!
Now back to Montserrat and pyroclastic
The 25 June 1997
pyroclastic surge that wrecked this sturdily-built house at Streatham,
Montserrat, caused no discernable damage to the nearby sugar mill. The
mill would have made a perfect shelter, if only people had realised the
danger in time.
The same mill can
be seen to the left of this view over the surge from the 11 February
2010 dome collapse that covered the Farrell's Plain area.
If you look very
carefully, you can see in the distance left another mill undamaged by
the huge surge that accompanied the 8 January 2007 PF down the Belham
What can Montserratians learn from the current agony around Merapi about simple
ways to survive a surge in or around their homes?
I’ve emphasised elsewhere (e.g. Topic 11) that Montserrat’s residents have
become totally acclimatised to their erupting neighbour and complacent about its
future activity. Perhaps the current Merapi eruption will help to knock a bit of
that complacency out of them. Despite the heroic efforts of the SAC to make
predictions about SHV “scientific”, they really have no more insight into what
the volcano may do next than any other group of Caribbean shamans reading
chicken entrails. The whole thing about both volcanoes and earthquakes is that
despite periods of relative predictability. The entire NDPRAC-equivalent
committee on Martinique who met repeatedly in 1902 to decide what to do about the
eruption of Mt Pelée nearby were
wiped out by the killer surge (PDC) between meetings.
Merapi gave no clues at all that it was beginning what has already become its
most deadly eruption for a century. I personally live in permanent fear that
those who “think they know” what SHV will do next will pay for their hubris with
their own or other peoples’ lives. This nightmare must haunt all sensitive
Governors and everyone around them.
The inability of hundreds of “at risk” Indonesians to move to safety before a
surge wipes out their village is a tragic but “classic” illustration of the
“frog in the saucepan” phenomenon (Topic 10). The Indonesian government
yesterday did the only thing that might persuade reluctant farmers, caring for
their precious cattle, to move away; they bought all the cattle. If
the Montserrat government had bought all the vegetables etc in the Streatham
area in 1997. I remember a neighbour in Washington DC in 1971 confessing that
she very nearly went back to her house to rescue the beloved family cat, despite
the news warnings that a dam above their evacuated neighbourhood was already
collapsing and that she might thus join the 150 others drowned during that awful
So let’s assume that you live in the Salem-Olveston area and have, by
bloody-mindedness, complacency, age, mental state, poverty etc managed to find
yourself in the path of a pyroclastic surge. Is there anything you can do to
help your survival, even if you lack a prepared sealed room? Here are some
suggestions, based on the photos from this Merapi eruption, together with other
recently published scientific studies on the subject, such as this one
about sheltering in buildings. Remember that your
objectives are to prevent your skin from scorching and to stop either hot air or
excessive dust entering your mouth.
1. Cover yourself as
completely as you can with cotton (or woollen but
artificial fibre) clothing.
2. Find spare clothes and
bury your head inside them.
3. Curl up beneath
your bedroom mattress. These three suggestions are poor substitutes for being a
furry monkey, but just might save your life.
4. If you have a shower,
turn it on fully and stand, fully clothed, beneath it.
5. If either you, or any
neighbours, have a swimming pool, dive in and try to stay below the surface for
as long as possible.
do this, if the pool does
have a modesty wall around it or lies on a dip in the ground (both are potential
PF/surge traps). The ideal pool is illustrated below; open and on a hillside.
Grab a drinking straw, if you have one, before your plunge and use it to take
occasional breaths. If no drinking straw, cover your head with your clothing and
stay under it when breathing.
Because most Montserrat homes are built on slopes, they each include an obvious
place to prepare for emergency shelter use. This is the cavity between the
ground and the lower-floor rooms. Make a small entrance to this cavity in the
downhill wall and fit it with a tight-fitting door. Even if your entire house
was swept away by the surge, as at Harris in February 2010, you would still be
cramped but safe in this cavity. Obviously ash could filter between floorboards
into your shelter and therefore take some extra clothing in to cover your face
and exposed skin (curl up, like that lucky monkey). Also keep some emergency
down there, in case your exit is across very hot ash and you must therefore wait
to be rescued. When things sound calm again, open the door a crack, wait for the
sounds of rescuers and then practice your yelling skills!
Incidentally garages, guest rooms etc in this part of your house are not
necessarily any better than a modest bolt hole in the foundations for keeping
you safe. How many such places on Montserrat are able to be sealed by steel
shutters, like the emergency rooms at MVO? Of course there is a very simple
solution to that problem but it will temporarily reduce your alcohol and
entertainment budget. Sorry!
The felled trees in this view tell you that the surge moved
(unsurprisingly) downhill from left to right. The damaged house on the
left gives excellent clues as to how to survive a surge, if you are
careless enough to be caught out by one on Montserrat (see text). All
the rooms above ground have been infiltrated by deadly ash, entering via
damaged shutters or through the wrecked roof. So where is the
potentially safe refuge?
Here’s another damaged house showing the potential safe zone
in its foundations
on the downhill side.
Maybe your (or of course your neighbour’s!) pool will one day save you
from an approaching surge. It would be simple during eruptions to keep a
full air cylinder and breathing tube at the bottom. Use your imagination
to survive or, better still,
why not evacuate when the sirens sound?
STOP PRESS in mid-December
two further important matters to report:
In June this year a multidisciplinary volcanology/museum/medical group published
their studies of Pompeii and Herculaneum skeletons, including several dozen
found in 2009 at the Roman settlement of Oplontis, a few km NW of Pompeii.
Oplontis was slightly nearer Vesuvius than Pompeii but further than Herculaneum.
By means of their combined studies, this team has been able to produce an
overall map of the dynamic pressures produced by the pyroclastic flows/surges
(called PDCs -- pyroclastic density currents -- in modern research literature)
throughout the region affected by the AD 79 eruption. At the same time, the AD
79 skeletons have proved to be so well preserved that the group's forensic
pathologists could determine the temperatures at which each person died, by
comparing the Roman bones with heat-treated modern ones. For readers, the
remaining excellent feature of this report is that it is published in
PlosONE, an internet journal of peer-reviewed
research that is available to everyone and not locked behind a subscription. For
the record, the details of the report are:
2. During early
December this year, another interdisciplinary team has visited
Merapi (funded by the EU programme called
MiaVita) and made a comparable
study of the disaster-hit region there. Because the residents
around Merapi are Muslims, there are strict limits as to what
studies may be made of their corpses. But, even with this
restriction, the new research should add enormously to our
understanding of such tragedies and hence how to reduce the risk
of more in the future.