Chapter Five
The Development of Volcanic Emergency Plans

From the Foreword:

"It is not the purpose of this handbook to discuss the details of the planning and organization needed to deal with volcanic emergencies, since these will of necessity vary from country to country according to political, social, legal and economic conditions and to the level of technological development. What has been attempted, is to distill from past experience in various parts of the world some general principles of organization and practice which, it is hoped, may prove to be of universal validity. The text has been kept as concise as possible, with numerous references to actual events."

"Against the more violent manifestations of volcanic activity, the only possible protection is escape from the threatened areas. Mass evacuation and other protective measures are more effective if they are planned and organized before an emergency aries. The main elements of pre- emergency planning are identified and discussed in chapter 5. Mass evacuation entails, however, major disruption of normal life for large numbers of people and is only undertaken when the risks of staying in a threatened areas are judged to be unacceptable."

"Awareness of the need to prepare for events such as volcanic eruptions and to provide protection against them, rather than simply to await and endure them, has been growing steadily throughout the world. It is hoped that this handbook will be of help to those involved in pre- disaster planning."

5.1 Introduction
5.2 Basic elements of the plan
5.3 Time scales
5.4 Identification of hazard zones
5.5 Population census and inventory of property
5.6 Identification of safe transit points and refuge zones
5.7 Identification of evacuation routes
5.8 Means of transport, traffic control
5.9 Accommodation in refuge zones
5.10 Rescue, first aid and hospital services
5.11 Security in evacuated zones
5.12 Alert procedures within government
5.13 Formulation and communication of public warnings
5.14 Review and revision of plans

5.1 Introduction

It will be assumed in this chapter:

(a) That in any community exposed to volcanic hazards there is general awareness of the hazard and of the attendant risks to life and property, and a general desire to take collective action to reduce these risks;

(b) That a legislative framework exists within which it is possible to plan, organize, and put into effect, at the national and at the local level, appropriate protective measures, including if necessary the evacuation of threatened areas and assistance to evacuees;

(c) That scientific knowledge of the potentially dangerous volcanoes is sufficiently advanced to permit the elaboration of "scenarios" of possible eruptions, their destructive effects and their social and economic consequences;

(d) That it will be possible to have some warning of impending eruptions, either from visible signs of volcanic activity or from scientific monitoring of the volcanoes, and that this warning will be given in time for appropriate action to be taken;

(e) That, if the above conditions are fulfilled, an emergency plan of action in case of eruption will be prepared for each potentially dangerous volcano.

The emergency plan for each volcano normal contains the following elements:

• Identification and mapping of the hazard zones;
• register of valuable movable property (excluding easily portable personal effects);
• Identification of safe refuge zones to which the population will be evacuated in case of a dangerous eruption;
• Identification of evacuation routes; their maintenance and clearance;
• Identification of assembly points for persons awaiting transport for evacuation;
• Means of transport, traffic control;
• Shelter and accommodation in the refuge zones;
• Inventory of personnel and equipment for search and rescue;
• Hospital and medical services for treatment of injured persons;
• Security in evacuated areas;
• Alert procedures;
• Formulation and communication of public warnings; procedures for
• communication in emergencies;
• Provisions for updating the plan.

One important question, which must be examined at the outset, is the relation between the time- scale of volcanic events and the time needed to put various protective measures (i.e., on-site protection and/or evacuation) into effect.

Experience has shown that the interval between the onset of an eruption, or of significant precursory phenomena, and a violent climax, eruption, may range from a few hours to several days, weeks or months. On the other hand, the time required to put emergency protective measures into effect depends on the size of the area at hazard, the density of population and settlement, the degree of mobility of the population, the transport and communication facilities available, and the general technological level of development. It will generally be measured in hours or days.

In practice, it will usually be appropriate to plan for two types of action:

1. Phased response to a gradually developing volcanic crisis, during which one may expect to have warning of potentially dangerous volcanic events at least 24 hours before they occur;
2. Immediate response to a situation calling for the fastest possible evacuation of people by whatever means are immediately available.

The more that is known about the history of a volcano, and the greater the effort that have been devoted to scientific studies and monitoring of its behavior, the easier it will be to foresee how much time may be available to take protective action when an eruption does occur.

The first element of a volcanic emergency plan is a map showing the hazard zones around the volcano which are liable to be affected by one or more destructive phenomena (pyroclastic flows, mudflows, lava flows, heavy ash falls, etc.) during an eruption. Such maps normally include the subdivision of the area exposed to each type of hazard into two or three subzones corresponding to eruptions of different magnitudes.

The maps of hazard zones will be based upon the maps drawn by volcanologists, showing the areas devastated during previous (historic, or geologically reconstructed prehistoric) eruptions. A detailed review of how these maps are prepared is give in a separate manual (Crandell et al., 1984). It is worth noting, however, that these hazard maps are based on purely geological criteria. For practical purposes, e.g. evacuation plans, etc., the local authorities responsible for emergency management may be obliged to extend the limits of some zones in order to take account of available escape routes, the boundaries of settlements, etc.

In order to plan for evacuation it will be necessary to compile a census of the population in the hazard zones and to update it a least once every five years, or whenever there are signs of abnormal volcanic activity. This census will include not only the people permanently resident in the zones but those who enter them regularly, for instance for their daily work. It may also be useful to establish an inventory of animal livestock in each zone, so that arrangements can be made for their removal if time and facilities permit.

Special note should be made of any property or facilities in the hazard zones whose loss or destruction would have immediate effects outside these zones (e.g., power stations, radio transmitters, telephone exchanges, water supplies, etc.).

If the evacuation of a hazard zone is to proceed in an orderly manner, it is essential that each person in the zone knows where to go when evacuation starts. For each hazard zone (or part of each zone), the nearest easily accessible point outside the zone may be identified, to which the people should go or should be taken, as quickly as possible, and where they may assemble in safety while arrangements are made for their reception in a refuge zone.

At each such safe transit point, arrangements will be made for evacuees to be identified so that, if necessary, a search can be made for any persons who may be missing. If several such transit points are set up, there should be good facilities for telephone or radio communication between them. All evacuees, including those proceeding to their own alternative accommodation in a safe area, should register their departure from the danger zone at one or other of the transit points.

The safe transit points will probably have only minimal facilities for the shelter and feeding of the evacuees. They should nevertheless be selected on the basis of a survey of buildings outside the hazard zones but easily accessible from them, to provide the best possible shelter for the anticipated maximum number of evacuees. In volcanic eruptions, tents are not suitable as temporary shelter, especially if sited close to a high-hazard zones, because they can be easily damaged by falling ash or lava lumps. Schools, community centers, warehouses or other large buildings will be preferred.

The plan will also specify the arrangements for the transfer of evacuees as quickly as possible from transit points to temporary accommodation in refuge zones elsewhere.

The next element in emergency planning will be to carry out a survey of the number of people to be moved to safety, the number of vehicles (and, if appropriate, boats and aircraft) available, and the serviceability and traffic capacity of each of the roads leading out of the hazard zones to the location, type and magnitude of the eruption, and according to the direction of the wind at the time. The main objective will obviously be to distribute the expected traffic flow as evenly as possible along all the escape routes which are likely to remain open. In this context, it will be advisable to consider the vulnerability of each route not only to ash falls, pyroclastic flows, mudflows or lava flows emanating from the volcano, but also to landslides and bridge or tunnel damage which may be caused by strong local earthquakes. Fine ash fall, even if only a few centimeters thick, may make asphalt road surfaces slippery, causing traffic congestion on steep slopes or accidents at corners and road junctions. Each of the escape routes will need to be examined, and measures taken as far as possible to control and maintain the traffic flow at expected danger points.

It is hardly necessary to point out that although the first consideration in selecting escape routes will be to move people as quickly as possible out of the immediate danger zone, it will also be desirable to bring them with the minimum delay to those safe areas where facilities exist for the reception and accommodation.

As has already been indicated, the plan for transporting people and their property out of the danger zones should be designed for two levels of emergency: namely, phased response and immediate evacuation. In a phased evacuation, when there is sufficient time between the official evacuation order and the onset of destructive eruption, one may assume that each family possessing its own vehicle or boat will look after itself and any neighbors for whom it has space and has made a specific commitment. All other evacuees will be collected by public transport from pre-arrange pick-up points. Each public transport driver, including especially hired or requisitioned truck drivers, will be instructed to collect people from one of these pick-up points (and not elsewhere). All private and public vehicle drivers will be briefed on which escape roads to use and when to leave. The public transport will continue to make return trips as long as roads remain open or until all evacuees and as much property as possible have been removed. In the event of an unexpectedly rapid escalation of destructive activity, transport will become increasingly difficult to control (due to attempts of people to scramble on to the nearest available truck or bus), and traffic movement along the escape routes out of urban areas may become impossible because of the large number of people leaving on foot. In this case, the plan will have to be abandoned in favor of a "crash" plan allowing any vehicles returning to the hazard zone to collect fleeing pedestrians at ad hoc pick up and turning points (preferably under police or civil defense control) along the escape route.

In order to plan evacuation transport in detail, it will be necessary:

(a) To establish how many people have private vehicles and/or boats, and to designate the routes these will follow;
 

(b) To make an inventory of the numbers and locations of people needing public transport;
 

(c) To designate pick-up points for public transport;
 

(d) To make an inventory of available public transport and drivers and to assign pick-up points to each of them;
 

(e) To make arrangements for requisitioning and fueling private trucks and buses (and boats if appropriate) and to provide any other necessary incentives to those normally based outside the hazard zones whose services may be required. It may be judged necessary or appropriate, for example, for the government to undertake to make good any loss or damage suffered by private vehicles or boats brought into the danger zone to assist with the evacuation.

Once the evacuees have reached the refuge zones, the problems of shelter, feeding, hygiene and morale will be similar to those of evacuees from any other natural or man-made disaster, and hence do not merit special discussion in a text on volcanic emergency management. There is, however, one factor in the case of volcanoes which does not normally apply to cyclone, earthquake or flood disasters: namely, that the eruption may continue for many months with repeated destructive paroxysms (possible exceeding in scale the first one), and that it may not be safe to allow or encourage the return of evacuees, or to commence rehabilitation and reconstruction, for many months after the initial disaster-causing event. Volcanic evacuations therefore often last longer than those caused by other natural phenomena.

During or after an evacuation, some people known to be living or working in a hazard zone may fail to appear at any of the safe transit points or in a refuge zone, and it may be necessary to organize searches for them. There may also be people isolated in areas which are not exposed to any danger but to which the access routes are blocked by pyroclastic flows, mudflows, or lava flows. There may be need for aerial and/or marine reconnaissance missions as soon as conditions are favorable, for food supply or rescue. It will be necessary to plan what equipment will be available and how such missions will be carried out.

First aid and hospital treatment will be needed mainly for three types of injury:

(a) Respiratory problems among people who have been exposed to breathing air laden with fine silicate dust, possibly also containing dangerous levels of H2S, SO2 and other volcanic gases;
 

(b) Broken limbs, lesions and bruises resulting from the impact of rock fragments or lava lumps falling from a great height;
 

(c) Skin burns (first to third degree) and burns to breathing passages and lungs, resulting from exposure to steam and hot dust clouds, especially those spreading from the fringes of pyroclastic flows. In the event of the latter, some of the casualties will probably be severely burnt over most of their bodies, and in critical condition.

In addition to the above, there may also be victims of toxic gases such as carbon monoxide (CO) or of suffocation in pools of carbon dioxide (CO₂) or other gases which may have accumulated in house cellars, valley bottoms or other low-lying places. Later, medical problems may arise from the drinking of water from reservoirs or tanks contaminated by toxic compounds.

Unless the danger to life is immediate and obvious, people will be reluctant to leave their homes without assurances that these will be guarded against burglary and looting during their absence. Adequate precautions must therefore be taken to prevent the access of unauthorized persons to evacuated zones, and regular police patrols of the zones should be maintained as long as this does not endanger the lives of the police.

As distinct from other natural hazards, volcanic hazards are strongly localized, the most destructive effects of eruptions being limited to areas within a few tens of kilometers of each volcano. The main responsibility for action of the kind described above may often devolve on local or provincial rather than national government agencies, except when the magnitude of the disaster is such that the local government is unable to cope with the situation.

The emergency plan will define the responsibilities of the various departments of government in dealing with the situation and the procedures by which the various elements of the plan will be put into effect when required.

Overall responsibility will generally be vested in an inter-departmental committee composed of representatives of the government departments concerned and presided over by the head of the national, provincial or local government. Each government department represented on the committee will prepare its own plans for action in response to alerts, in accordance with the directives give by the committee.

In general, it will be possible to define several stages of alert, each corresponding to a different level of hazard as assessed by the scientific team monitoring the volcanic activity. The responsibility for declaring the various stages of alert will lie with a designated official, who will act on the advice of the scientific team monitoring the volcano. There will usually be an element of personal scientific judgment in deciding what interpretation to place on the observed volcanic phenomena and much will depend on knowledge of the past history of the particular volcano. In practice, the decision as to which stage of alert has been reached may often be based not so much on an objective assessment of the probability of a violent eruption as on the number of false alarms which can be tolerated without loss of confidence by the civil authorities and by the public.

Since the measures that can be taken to protect life and property during a volcanic eruption will affect to some degree the whole population, it is of vital importance to keep the public fully and accurately informed of the nature of the hazard and of what is being done (and what they should do) for their protection. This inevitably entails some degree of control of the information transmitted to the public by the news media. This control will usually be exercised by a responsible official on behalf of the government. In order to avoid panic or other adverse reactions to the situation, the form and content of public announcements will, as far as possible, be decided in advance of any emergency, and the public will be familiarized with the arrangements made for their information, so that they know what to expect. The details of these arrangements will vary from place to place and from country to country, according to the political and social structure of the community and the technical means available. It is therefore difficult to lay down any detailed guidelines for public information and warning. However, as an example, we give here model texts that could be used to announce by radio the two highest levels of alert.

No plan of this kind will remain for ever valid, and it will always be advisable to provide for its review and revision with appropriate publicity at regular intervals, say every two or three years. Changes may become necessary as a result of:

(a) Progress in scientific knowledge of the volcano in question, which may lead to a redefinition of the hazard zones around it

(b) Changes in the pattern of settlement around the volcano, in the road system, communication networks and other technical infrastructure, which will modify the procedures for warning and evacuation in emergencies

(c) Changes in the administrative structure of the national or local government

In addition, the plan will certainly have to be revised after each eruptive episode, in the light of the practical experience gained. Some imperfections in the plan will probably be revealed by any real emergency, no matter how much thought and planning has been put into it beforehand. This implies the existence of some permanent organization within the national or local government, with prime responsibility for preparing and executing emergency plans for volcanic and other potential causes of disaster.