Cover Image
close this bookSevere Tropical Storms Preparation and Response - Case Study Text (DHA/UNDRO - DMTP - UNDP, 1991, 58 p.)
close this folderPart Two: Disaster and Response
View the documentE. Detection and Warning of the Storm
View the documentF. Characteristics of the Threatened Area
View the documentG. Actions at the Provincial and Local Level in Response to Warning
View the documentH. Primary Impact
View the documentI. Secondary Effects
View the documentJ. Shortcomings in Management of the Response

H. Primary Impact

Even before landfall, the Cyclone had killed most of those who died - more than three thousand people. Its winds and high waves destroyed hundreds of fishing boats, many of them small, three or four person vessels, which were sheltering in the lee of islands, or had been beached on low shores. Bodies of fishermen continued to be washed ashore for several weeks, and most were never properly identified.

Cyclone Zelda slammed ashore into the town of Grenora at 8.30 on the morning of 4th October. Winds of 30 to 50 km per hour had been building up since the previous evening, and there had been continuous heavy rain for the past 24 hours. But no one expected the force of the impact. Most of the population were in their houses. The next ten hours were a shrieking, soaking, battering confusion of flying debris, falling trees, driving rain, disintegrating houses, breaking glass, and rising flood, as people clutched their children, crouched under carpets, fled across spaces ripped by flying iron sheeting, and clawed their way into neighbouring houses in search of respite. Half way through the afternoon the passage of the eye of the storm brought a still, humid, awesome quiet. Some people, believing themselves safe, carried injured relatives into the streets, searched for the missing, or tried to salvage possessions. Half an hour later the opposite wall of the eye rolled across the town, whipping up the debris of a thousand broken houses and cutting down those still outside. Only at dusk did the wind falter, and then darkness covered streets awash with floodwater, carrying tile, metal, and dented up-turned cars, wooden beams, branches, and paper everywhere.

The Cyclone moved on, inland, deroofing most houses, destroying many buildings completely, and flooding some areas to a depth of three metres or more. Most structures on a path one hundred kilometres wide were rendered uninhabitable. Almost all roads in the area were blocked by flooding and fallen trees. All towns in the area lost power - a population of three million people was without light that evening.

The death toll on land by the evening of the 4th October was approximately three hundred. One hundred and eighty of these had been caught in the storm surge in two villages close to the town of Grenora, as houses built over the beachfront collapsed, and as a group of workers fled across a sand-bar. Another forty were killed in the town of Grenora itself, mainly by the collapse of roofs into public buildings, by flying metal roof-sheeting, by drowning, and falling trees. The rest died in house collapses, flash flooding, landslips, automobiles and buses, and in attempts to wade to higher ground.

By dawn next morning the extent of flooding, and the damage to buildings was obvious, both from the air and from the ground. Damage to housing was almost universal. There was widespread loss of corrugated metal sheeting, loss of asphalt shingles, loss of the roof structure, blown out windows and doors, and collapsed timber and concrete blockwall buildings. Specific aspects of local domestic building practice contributed to additional damage, including the method of fixing wooden rafters in concrete lintels, and the increasing tendency to build low-pitched roofs with overhanging gables. Many of the weaker buildings had simply collapsed into a pile of wooden sticks and broken sheeting.

Damage to government buildings was also extensive. Again, roof structures commonly failed. There was also serious damage to interiors, caused by driving rain and flooding. Government offices in the main towns of Morenia and Galenna were largely unusable.

Damage to public utilities had significant knock-on effects immediately. A key element was the interdependence of these systems. Power needs communications, water needs power, hospitals need water, restoring utilities needs an open road network, and so on. Most of the communications towers and masts failed (microwave, HF, and VHF). These were uniformly under-engineered for high winds, poorly anchored, and on inadequate foundations. Corrosion of unprotected steel structures further contributed to structural failures. The power and electronic equipment associated with microwave towers was severely damaged first by horizontally driving rain, and often also by loss of windows and roofs and the impact of flying debris. Telephone exchanges in the area were severely damaged by water and flying debris. Some were flooded. Rain damage to switchgear for alternative power supplies (together with inadequate maintenance in some cases) prevented rapid recovery of the less damaged facilities. The entire trunk telephone network was inoperative throughout the region.

Roofing blown off of most housing


Main power lines were badly damaged


Overground lines of both telephone and electricity transmission systems failed at numerous points. A major contributory factor was the failure of wooden poles weakened by rot and insect damage. Electricity transmission was especially vulnerable where long spans crossed deep valleys.

Most of the main hospitals experienced failure of roof fixing bolts, hooks, and washers. Flat, metal sheeted roof contributed to vulnerability, with tearing of thin sheet at fixings. Large glass panels blew in. Poor maintenance, resulting in corroded fittings, meant that the cladding of several buildings ripped off, causing debris-damage, a number of injuries, and problems moving vehicles up to the buildings.

Many school buildings were badly damaged. Their shape and design contributed to this. They were narrow and long, with flat pitch roofs and gable ends. Some metal-frame schools suffered corrosion of the frame and roof elements and this greatly increased the chance of roof collapse.

Casualties and their Treatment

Injuries were closely related to building failure in many areas. Subsequent analysis showed that the rate of injuries overall was about 4700 per 100,000 exposed people. The rate of serious injuries, requiring immediate hospital attention, was less than 400 per 100,000. The most common injuries were lacerations of the arms and back from flying debris, and cuts from broken glass on the feet. Most injured people were isolated by flood waters, and unable to reach any site for treatment for at least two days. The vast majority of injured walked by themselves to clinics or first aid centres to seek treatment. About 150 injured people were eventually moved in boats to the nearest roads, and thence to major hospitals. Generally, boats often served best as ferries on flooded sections of roads.

At hospitals and clinics, there were shortages mainly of dressing materials, orthopaedic splints, and major pain-killers, but the quantities required for replenishment were described by one hospital manager as “logistically trivial”. It was later estimated by a senior relief official that one well-prepared medical unit with one helicopter (or indeed, three taxi-cabs in part of the region) could have accomplished all of the significant emergency medical replenishment for the medical system.

With the exception of relatively small number of severely disabling head and spinal injuries and some amputations (a total of about forty people), and several hundred people with disabling injuries to joints and muscles, most of the medical caseload had been dealt with by the end of the first week, mainly by hospitals in the area.

Damage caused by Cyclone to National Hospital

J-S. Tyndale-Bisco Photo, UNDRO NEWS 9/10.88

Schools damaged by cyclone


Damage and Needs Assessment

An overall picture of conditions in the affected area was in fact built up quickly, not by some large pre-established reporting system (for there was none) but by a carefully planned, small-scale action by small teams formed several months beforehand. There were two groups of assessors. The first, a joint programme involving staff from the armed forces, the police, the UN Disaster Management Team, and the Red Cross, limited themselves mainly to overflights of the whole area in helicopters, and visits to the main urban centres of damage. Their objective was mainly to get a sense of the scale and scope of the disaster, the boundaries of the affected area, and the limits on access. These teams ended their missions with high morale, but experienced a number of disturbing incidents in which they were forced to decide between moving injured people, women in labour, and other people in urgent need and completing their primary mission of information collection.

The second team attempted to obtain a more scientific assessment of risks and needs throughout the area. An early sample survey of the Cyclone-affected area was co-ordinated by two staff from the Ministry of Health, using four two-person teams, flown by helicopters provided by a multinational company and by a USAID charter. Sampling sites were selected during overflights, and two person teams then flew to centrally located relief centres, to interview individuals about personal losses, village losses, and immediate needs. Conditions and supply requirements were discussed with local relief officials, and all available ill and injured people were examined clinically. Radio links with the police network, together with the excellent personal and working relationships between the police air unit and local ministry officials, enabled the teams to call up police helicopters for casualty evacuation on the few occasions where this was required. Sources of drinking water were tested for salinity. The teams summarised their findings each afternoon, and these summaries were collated, edited, and issued nightly to the Government EOC and to several major donors. A total of eighteen sites were visited during this first survey, enabling the team to generate an estimate of overall mortality, losses of housing, and overall Cyclone-related morbidity. The relative absence of excess levels of communicable disease was noteworthy, providing further evidence to resist the widespread clamour for mass-immunization. Water sources were found to be mostly usable.

Immediate Needs for Most People

The immediate problems facing the population were shelter and food. Those who were marooned outside for several days became very hungry, their condition exacerbated by constant drenching in the continuing rain. Reconstruction of shelter from debris was certainly possible. However, there were no stocks of nails or rope, few tools, and most survivors were extremely tired. The inclination of many people was to gather their remaining possessions, and to leave the area to seek refuge with relatives or friends elsewhere. But some, especially those with only moderately damaged homes, quickly began to patch up damage using salvaged materials. The occasional distributions of plastic sheet and tarpaulins by the Army, government officials, or NGOs, while widely welcomed, mainly served as coverings for salvaged possessions.

Food, however, remained the main preoccupation. Shipments of cooked grain and bread brought in by the Army, and by people from neighbouring provinces, were appreciated by all. But distributions were inevitably confined mainly to the more densely populated areas. To a large extent, people in less damaged houses shared remaining food stocks and cooking fuel with their neighbours. Merchants quickly began to sell salvaged stocks in markets even in the more damaged areas, and prices, though at least double the pre-impact levels, were still within reach of most people, who had managed to protect household stores of cash.

Managing Public Health

There was widespread concern about the quality of water supplies, and some local rumours (incorrect for the most part) of water-borne epidemics. Within the more densely populated urban areas, staff from the Ministry of Health had quickly moved to monitor free chlorine levels and bacterial contamination in public water supplies, following detailed instructions given in a number of seminars and training programmes the previous year. In the city of Morenia, staff of the water utility corporations were so familiar with their systems that once broken domestic connections had been isolated, delivery of water in quantity to stand-pipes was quickly restored. However, the vulnerability of the water system to both electricity failure and debris damage to chlorination apparatus was clear. A number of hasty improvisations had to be made to connect the pumps to diesel generators supplied by the Armed Services. The system had to resort to batch chlorination, using supplies of high test hypochlorite brought in by helicopter. Before this was done, two hundred thousand people in Morenia were without clean drinking water for two days. The need for structural mitigation measures in this part of the system was obvious.

Deteriorating sanitary conditions in a number of schools and churches housing displaced people were causing particular concern to Ministry of Health staff. A major problem was the lack of sufficient water storage to match the numbers living in and around the buildings. Once collapsible water tanks had been brought in, and supplied with water by tanker, the risk of diarrhoeal disease outbreaks declined somewhat, but the problem was never adequately dealt with. Within a week, most of the centres were emptying fast. Health officials focused much of their epidemic surveillance activity on these centres, and on the poorer sections of the main towns. In addition, all hospitals were requested to report the last known location of any patients showing a range of communicable disease symptoms.

To their own surprise, health officials managed to resist pressure for indiscriminate mass cholera immunization from the Minister of Health himself. The combined appeals of the WHO representative, a USAID consultant, and a visiting senior official from the US Public Health Service, together with a well-informed CNN reporter, finally prevailed.

Distribution of Casualties and Damage

Even at this early stage, the relationship between poverty and vulnerability were becoming clear. Injury and death rates were higher in the poorer sections of most towns. Particular occupations, and social groups, had suffered disproportionately. The high death toll among poorer fishermen was noteworthy.

Damage to industrial resources was widespread. Within the relatively narrow corridor of major damage, most of the larger industries involved processing of agricultural products. Outside stores of raw product were mostly lost. Much machinery was damaged by metal roofing sheets blown from the large expanses of roofs. Sixty kilometres to the south, the new Freeport, with its container port, natural gas terminal, and refining complex, had experienced significant damage from 150 km per hour winds. Most of the completed capital facilities were relatively unaffected. However, plant still under construction was much more seriously damaged, and flying debris from these units caused specific, highly expensive damage to critical catalytic units and control valves. Noteworthy also was the level of damage to computerised control systems at the natural gas plant, mainly from wind damage to roofs, combined with inadequate rain protection for electronic equipment. Little had been done beforehand to provide expedient protection, and it was clear that the roof design of buildings containing this equipment was inappropriate. Equally serious in terms of disruption was the level of damage to the temporary buildings in which construction workers lived, and in which key tools and materials were stored, beside the sites. Many of these were completely destroyed. Lost also were the pay and personnel records of the largest construction firm, and the firm providing security services. It quickly became clear that construction would be delayed by several weeks, at least.