volcano's behaviour.
The probable style of eruption (e.g., an explosive eruption
or the extrusion of a lava dome) and its impact, especially
the location and size of the area most likely to be affected.
The assessments are made by studying the products from previous
eruptions from your volcano and, also, using experience gained
from similar types of volcano around the world. The results
will normally be presented as a hazard zonation map that shows
the areas likely to be affected by a particular style of eruption.
The preparation of a risk zonation map, based upon the hazard
map. This will define the absolute and relative threat to population
centres on and around the volcano and will form a critical element
in the operation of an effective system of alert levels, and
in the development of evacuation and resettlement plans.
The construction and form of a system of alert levels requiring
specific actions by the EMC and the public in response to the
escalation of activity through a series of pre-defined criteria
based upon changes in the volcano's behaviour (e.g. Montserrat
alert level system - appendix 5.6)
If more than one style of eruption is expected, the relative
probability of the different styles taking place (e.g., "Extrusion
of a lava dome, X%. Explosive eruption, Y%")
During an eruption, scientists can advise on:
Short-term changes in the level of activity. For example, by
monitoring the numbers and types of earthquake, or the rate
of swelling of the ground surface, estimates can be made as
to whether an eruption may be accelerating towards stronger
activity or, conversely, coming to an end.
Changes in the areas under threat. These may occur because the
eruption itself alters the shape of the volcano. For example,
a growing lava dome may cause an old crater wall to collapse,
so allowing pyroclastic flows from the dome to travel in directions
not previously possible. Changes will also occur if the eruption
becomes stronger or decays. These are likely to necessitate
modifications to hazard and risk maps as the eruption develops,
perhaps also entailing changes to the system of alert levels.
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Specific, appropriate measures for mitigating risk. Such measures
may include - for example - the dredging of rivers filling with
ash and volcanic mud in order to reduce the risk of overspilling
and flooding, or the removal of accumulating ash from roofs
to prevent structural collapse.
Allocate a science liaison officer from the information team
(ideally an individual with some scientific background or knowledge)
and ensure that a stable and good relationship is built up with
the monitoring scientists, even if nothing is happening at your
volcano. Publicise the fact that regular contact is being maintained.
This will help reduce media pressure on the scientists and also
strengthen public confidence that preparations for future volcanic
emergencies are being taken seriously.
Discuss possible eruption scenarios and their impact. Design
a series of basic plans that can be implemented rapidly at the
start of an emergency (although these may have to be modified
later to account for specific conditions during a crisis).
Work with the scientists to develop hazard and risk zonation
maps and an effective system of alert levels. Use this information
to plan emergency evacuation and resettlement measures.
Establish with the scientific team the sort of information that
will be most useful to you in preparing an emergency plan, and
in what form this information will be provided. Make sure that
you are familiar with key scientific terminology and understand
the limits to the type of scientific information that will be
available during a crisis. Do not hesitate to ask for as many
explanations and clarifications as you might need: it is better
to learn before a crisis develops.
Utilise the scientists to help to educate the public about the
volcanic threat. This can be done via public meetings, radio
interviews, giving talks to schools and other institutions,
exercises and simulations, and by seeking their involvement
in the preparation and dissemination of literature. |
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