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Following the El Niño occurrence of 1982-83, the member states of the Organization of American States (OAS) expressed the need for technical cooperation in natural hazard management. In response, the Department of Regional Development and Environment (DRDE) initiated the Natural Hazard Project with support from the Office of Foreign Disaster Assistance (OFDA) of the U.S. Agency for International Development (AID). OAS by that time had been providing services in regional development planning for over twenty years and in 1984 published Integrated Regional Development Planning: Guidelines and Case Studies from OAS Experience. In keeping with the principles set forth in that book, the OAS approach incorporates natural hazard management issues into the development planning process.

The services of technical cooperation, training, and technology transfer focus on hazard assessment and mitigation as elements of the processes of environmental assessment, natural resource evaluation, and project formulation. The technical cooperation concentrates on hazard and vulnerability assessments, inclusion of hazard mitigation measures in the formulation of investment projects, use of geographic information systems for mapping and analysis, and urban watershed planning for hazard and resource management. Training includes workshops and formal courses in a variety of aspects of disaster mitigation and integrated development planning. Personnel from virtually every member state have been trained in new hazard management skills. Technology transfer to date has focused on the establishment of geographic information and emergency information management systems, including provision of equipment and training of personnel. The effectiveness of reducing the impact of disasters by including natural hazard management as an element of development planning has been confirmed by the recipient countries and by other international organizations.

The need for this book became clear through field work and discussions with planning agency counterparts and representatives of other development assistance agencies. Great strides were made in the past two decades in emergency preparedness and response, but up to now insufficient attention has been paid to reducing the vulnerability of existing and planned development. After seven years of field work, it is now possible to prepare this synthesis of OAS experience with this neglected subject.

The material comes with a broad set of objectives, a reflection of the breadth of the issues involved in hazard mitigation. At the policy level, it is hoped that national planning ministries, development agencies, and international financing institutions will be encouraged to systematically include analyses of natural hazards in their economic development programs. Specifically, it is hoped that the experience will persuade:

- development agencies in the member states to incorporate natural hazard considerations into the process of integrated development planning;

- international technical cooperation and financing agencies to incorporate hazard considerations into the formulation of investment projects at the earliest stages;

- governments and financing agencies to place more emphasis on risk awareness in evaluating investment projects, and to assume a stance of risk avoidance rather than risk neutrality; and

- bilateral and multilateral aid donors to re-evaluate the distribution of their disaster relief funds, increasing the proportion for prevention activities.


This Primer has been prepared as reference document for practitioners in the field, to guide integrated development planning teams in Latin America and the Caribbean in the use of natural hazard information during the different stages of the planning process. The information presented here is specifically oriented toward regional planning studies, whether the area in question is a few hundred or a few hundred thousand square kilometers, and complements other planning information that is typically gathered and analyzed during the course of the study. The methods have been selected for their utility in the regional planning process.

In some cases the information and methods are to be used "as is" during the study; in other cases, the Primer offers guidance on the acquisition of information or the selection of methods, presenting questions to be asked and decisions to be made by the planning team.

The Primer is divided into three parts, each covering a specific subject area and complementary to the others. Each part, with the chapters contained therein, is meant to provide the planning team sufficient guidance in that subject area for it to proceed with the task at hand. There is extensive cross referencing between chapters. Since the book is intended for reference, each chapter is complete within itself (even though this results in some redundancy), with its own detailed table of contents, a short summary, a statement of its objective, and complete references.

If there is an unevenness to the contents of the these parts, it is a reflection of the incipient state of natural hazard assessment in the integrated development planning process. In subject areas where assessment techniques, information, and/or planning study methods are generally available, the Primer so informs the user without necessarily presenting the technique, information, or method. In other instances, the contribution of the Primer is to present to the planning team heretofore unavailable elements, or to propose and explain the use of elements specifically created for integrated regional planning purposes.

All readers should start with Part I. The core of Chapter 1 is the section "Hazard Management and Development Planning," which describes the process of integrated development planning as practiced by the OAS and indicates the hazard management activities associated with each stage of that process. A second feature is the description of how to conduct natural hazard assessments for selected economic sectors. The chapter ends with a set of strategies for development assistance agencies interested in implementing the recommendations. Chapter 2 is vital to all practitioners who formulate investment projects: it explains how to include natural hazard risk consideration as an integral aspect of project preparation. Taking as a point of departure that the most effective way to persuade decision-makers to include hazard mitigation measures in a development project is to demonstrate the cost-effectiveness of the proposal, the chapter briefly presents principles of economic analysis, then provides guidelines for conducting various kinds of economic analyses appropriate for different levels of available information. While the rest of the book deals with the issue of how human activities can mitigate or exacerbate the impact of natural hazards, Chapter 3 shows that one of the services provided by ecosystems is the natural mitigation of hazards until that service is undermined by environmental degradation.

The chapters of Part II can be read when the need arises. Planners, particularly those working in large study areas, should be aware of the great variety of remote sensing devices, mounted in both airplanes and satellites. Chapter 4 gives a general orientation on the applications, limitations, and costs of the main remote sensing techniques and tells where to look for additional detail. Any modern planner or development practitioner should be aware of the great power of:

Natural hazard assessment: an evaluation of the location, severity, and probable occurrence of a hazardous event in a given time period.

Vulnerability assessment: an estimate of the degree of loss or damage that could result from a hazardous event of given severity, including damage to structures, personal injuries, and interruption of economic activities and the normal functions of settlements.

Risk assessment: an estimate of the probability of expected loss for a given hazardous event.

Integrated development planning is a multidisciplinary, multisectoral process that includes the establishment of development policies and strategies, the identification of investment project ideas, the preparation of projects, and final project approval, financing, and implementation. The OAS/DRDE version of this project cycle consists of four stages: Preliminary Mission, Phase I (development diagnosis), Phase II (project formulation and preparation of an action plan), and Project Implementation. The development planning and hazard management activities in each of these stages are summarized in the diagram on the next page.

The advantages of incorporating hazard management into development planning include the following:

- Vulnerability reduction measures are more likely to be implemented as part of development projects than as stand-alone mitigation proposals.

- The cost of vulnerability reduction is less when the measure is a feature of the original project formulation than when it is incorporated later.

- The planning community can help set the science and engineering research agenda to focus more on the generation of data suitable for immediate use in hazard mitigation.

- Building vulnerability reduction into development projects benefits the poorest segments of the population.


Examples of structural measures that can mitigate the effects of natural hazard events include building codes and materials specifications, retrofitting of existing structures to make them more hazard-resistant, and protective devices such as dikes. Non-structural measures concentrate on identifying hazard-prone areas and limiting their use. Examples include land-use zoning, tax incentives, insurance programs, and the relocation of residents away from the path of an event. A strong case can be made for emphasizing non-structural mitigation in developing countries, since structural mitigation measures often have a high direct cost that must be added to the costs of a project. Non-structural measures may have some capital and/or operating costs but these are usually less than structural costs.

Several questions enter into the issue of risk vis-a-vis investment projects:

Should risk be considered in the evaluation of investment projects?

Governments may argue that they should be indifferent between high-risk and low-risk public sector projects that have the same expected net present value because the risks, being widely shared throughout the society, are negligible to each individual. But this ignores governments' obligation to consider the opportunity cost of each investment. International financing agencies can be indifferent to risk because the country will be obligated to repay the loan whether or not the structure

OAS/DRDE Natural Hazard management process


Geographic Information Systems (GIS)

A GIS, a systematic means of geographically referencing information about a unit of space, can facilitate the storage, retrieval, and analysis of data in both map form and tables. It can be a manual system, but most GIS are computerized, as dictated by the overwhelming number of pieces of information needed for natural hazard management, particularly in the context of development planning. A GIS can be surprisingly inexpensive; it can multiply the productivity of a technician; its use can give higher quality results than can be obtained manually regardless of the costs.

Remote Sensing in Natural Hazard Assessments

Remote sensing refers to the process of recording information from sensors mounted either on aircraft or on satellites. These techniques can be used to reveal the location of past occurrences of natural events and/or to identify the conditions under which they are likely to occur, so that areas of potential exposure can be distinguished and applicable mitigation measures can be introduced into the planning process. Aerial and satellite remote sensing techniques appropriate for the preparation of assessments will vary with the type of natural hazard and the stage of a development study under consideration.

Special Mapping Techniques

Multiple-hazard maps combine assessments of two or more natural hazards on a single map. Such a product is excellent for analyzing vulnerability and risk since the combined effects of natural phenomena on an area can be determined and mitigation techniques suitable for all can be identified. Critical facilities-transport and communication facilities, utilities, large auditoriums, hospitals, police and fire stations, etc.-must also be mapped as a part of the process of emergency planning. Combining critical facilities mapping with multiple hazard mapping provides information to guide the identification of projects and mitigation measures.


Activities that technical cooperation agencies can undertake to promote natural hazard assessment and mitigation include:

- Strengthening planning institutions' ability to incorporate natural hazard considerations into the planning process.

- Supporting pilot projects of natural hazard assessments.

- During relief and reconstruction efforts in the aftermath of a disaster, stimulating the interest of the government and development assistance agencies in natural hazard assessment and mitigation.

- Building natural hazard assessments into sector planning.

- Including in the preparation and evaluation of investment projects the costs and benefits of incurring vs. avoiding the impacts of natural hazards.

- Preparing case studies of noteworthy experiences that show how funding activities can be made more responsive to natural hazards.

A strategy to promote lending and donor agency interest in hazard assessment and mitigation consists of three elements:

- Change the context in which the lenders and donors perceive governments and technical cooperation agencies to be addressing natural hazard issues. Recipient countries can show their capacity to deal with natural hazards by focusing on priority hazards and sectors; by choosing simple, practical information collection and analysis systems; and by demonstrating a commitment to implementing study findings. Technical cooperation agencies can make study outputs appeal to lenders and donors by seeking practical and cost-effective solutions to recurrent problems and can identify mechanisms of cooperation with financing agencies such as pooling technical resources, exchanging experiences, and joint staff training in natural hazard issues.

- Establish incentives for analysis. Development financing agencies will be more willing to incorporate natural hazard considerations into project preparation and evaluation if minimum change in existing procedures is required. Ways to promote this include providing reusable information, integrating hazard concerns into existing review mechanisms, promoting proven mitigation measures in relation to specific types of projects, incorporating appropriate costs and benefits of hazard mitigation into economic appraisal, and sensitizing staff members.

- Assign accountability for loss. Bank directors and staff should be made more aware that projects they plan or fund may suffer losses from natural disasters. Losses from natural disasters should be evaluated in the context of the lender's program area and its project design and repayment performance. The inclusion of techniques to deal with natural hazards management issues in the professional standards of bank staff should be promoted.


Natural hazards, like natural resources, are part of the offering of our natural systems; they can be considered negative resources. In every sense natural hazards are an element of the "environmental problems" currently capturing so much public attention: they alter natural ecosystems, heighten the impact of those ecosystems' degradation, reflect the damage done by humans to their environments, and can affect large human populations.

While virtually every book about natural hazards contains a chronicle of death and destruction, a similar accounting of damage avoided is almost never included. But the effects of the disasters caused by natural hazards can be greatly reduced by action taken in advance to reduce vulnerability to them. Industrialized countries have made progress at reducing the impacts of hurricanes, floods, earthquakes, volcanic eruptions, and landslides. For example, Hurricane Gilbert, the most powerful hurricane ever recorded in the Western Hemisphere, was responsible for 316 fatalities, though less forceful hurricanes killed thousands of people earlier in the century. A combination of zoning restrictions and improved structures together with new prediction, monitoring, warning, and evacuation systems made the difference. Latin American and Caribbean countries have reduced loss of life from some hazards, principally through disaster preparedness and response; they now have the opportunity to reduce economic losses through mitigation in the context of development to a much greater extent than they have to date.

The disasters caused by natural hazards generate a demand for enormous amounts of capital to replace what is destroyed and damaged. The development community should address this issue because it affords, among all environmental issues, the most manageable of situations: the risks are readily identified, mitigation measures are available, and the benefits that accrue from vulnerability reduction actions are high in relation to costs.


With depressing regularity, natural disasters become international headlines. Each year one or more hurricanes strike the Caribbean region. Particularly destructive ones, such as Gilbert in 1988 and Hugo in 1989, can cause billions of dollars of damage. Flooding, too, occurs annually, but no reliable estimates are available of the cost in human lives and property. Earthquakes and volcanic eruptions occur unpredictably with disastrous effects: the mudslide precipitated by the eruption of Volcán Ruiz in Colombia in 1985 killed 21,800 people, and earthquakes in Mexico (1985) and El Salvador (1986) together killed more than 10,000. Landslides are limited in area, but occur so frequently that they account for hundreds of millions of dollars in damage every year. While not as spectacular, drought can be more harmful to agricultural production than hurricanes. After the 1971 drought, for example, banana production in Saint Lucia did not recover fully until 1976. Disaster aid, however, is scarce in the region for this type of pervasive, slow-onset hazard.

Over the past 30 years the average annual costs of natural disasters to Latin America and the Caribbean were 6,000 lives, adverse effects on 3 million people, and US $1.8 billion in physical damage and economic losses. Moreover, the impacts are increasing: during the 1960s approximately 10 million people were killed, injured, displaced, or otherwise affected; the number for the 1970s was six times larger, and for the 1980s, three times larger.

A conservative estimate of the impact of disasters on the region from 1960 to 1989 is given in Figure 1. It can be seen that droughts and floods affect the largest number of people; earthquakes account for the most deaths; and earthquakes, floods, and hurricanes cause the most financial damage. Hurricanes are the most devastating natural hazard in the Caribbean region, earthquakes in the Mexico-Central America region. Floods, droughts, volcanic eruptions, and earthquakes are all very destructive in South America. Figure 2 summarizes the effects of some of the worst disasters of the period.

In addition to the direct social and economic impact, natural disasters can affect employment, the balance of trade, and foreign indebtedness for years after their occurrence. After Hurricane Fife struck Honduras in 1974, for example, employment in agriculture decreased by 70 percent (World Bank, 1979). Funds intended for development are diverted into costly relief efforts. These indirect but profound economic effects and their drain on the limited funds now available for new investment compound the tragedy of a disaster in a developing country. Furthermore, international relief and rehabilitation assistance has been insufficient to compensate countries for their losses; during the period 1983-1988, reconstruction assistance amounted to only 13 percent of the estimated value of losses.

Yet natural hazards appear to generate little constituency for their prevention.


Source: Office of Foreign Disaster Assistance/United States Agency for International Development. Disaster History. Significant Data on Major Disasters Worldwide, 1900-Present. July, 1989 (Washington, D.C.: OFDA/USAID, 1989).


The losses are a concern not only for the countries in which they occur but also for international lending agencies and the private sector which are interested in protecting their loans and investments. The investments are often at risk of both natural hazards and the side effects of development projects that exacerbate these hazards. For example, excessive erosion and siltation reduces the useful life of large multipurpose dams. Many smaller dams in the region also experience this type of damage: accelerated erosion caused by a hurricane filled half the storage capacity of a reservoir in the Dominican Republic virtually overnight. As a result of these concerns, one important lender, the Inter-American Development Bank, is studying the process of evaluating dam projects on the grounds that more realistic methods of estimating life expectancy and cost-benefit ratios will have to be introduced if the problem of erosion and siltation cannot be resolved satisfactorily for any project.

While the development efforts of the past have brought economic advancement to many parts of the world, they have also brought unwise or unsustainable uses of the natural resource base. Indeed, in recent years, the United Nations specialized conferences on the human environment, desertification, water management, deforestation, and human settlements all point to environmental degradation brought about by development, and the corresponding reduction in the capacity of an ecosystem to mitigate natural hazards.




Event type

Number of fatalities

Affected population b/ (thousands)

Economic losses (million US$)

International assistance c/ (million US$)

Antigua & Barbuda





- -







































- -













- -




























Hurricane Joan




- -












- -


El Salvador







Eastern Caribbean Islands d/


Hurricane Hugo



- -




Hurricane Gilbert













Hurricane Gilbert














Hurricane Joan




- -




























a/ Information for all columns but International assistance was obtained from the United States Agency for International Development/Office of Foreign Disaster, Disaster History, Significant Data on Major Disasters Worldwide, 1900-Present, August 1990 (Washington, D.C.: USAID/OFDA, 1990). Damage estimates may be preliminary and therefore, other sources may show different figures.

b/ Excluding fatalities.

c/ Information obtained from United States Agency for International Development/Office of Foreign Disaster Assistance, OFDA Annual Report FY 1983, 1984, 1985, 1986, 1987, 1988, and 1989 (Washington, D.C.: USAID/OFDA, 1983-1989). Disaster assistance figures do not include contributions from international reconstruction loans and grants.

d/ Information obtained from a preliminary report from the United States Agency for International Development/Office of Foreign Disaster Assistance (USAID/OFDA), "After-Action Report of the Hurricane Hugo OFDA Disaster Relief Team" (Washington, DC: OFDA, 1990).

- - Information not available.

Nevertheless, development agencies often continue to operate as though their activities and natural disasters were separate issues. As Gunnar Hagman (1984) points out in Prevention Better than Cure:

When a disaster has occurred, development agencies have regarded it as a nuisance and tried to avoid becoming involved; or even worse, the risk of existing or new potential hazards has been over-looked in the planning and implementation of some development activities. It is now being observed that intensive development may be the cause of many new disasters in poor countries.

Until quite recently, in fact, many practitioners believed that development efforts themselves would spontaneously provide solutions to problems posed by natural hazards. In 1972 the United Nations Conference on the Human Environment in Stockholm declared:

Environmental deficiencies generated by the conditions of underdevelopment and natural disasters pose grave problems and can best be remedied by accelerated development through the transfer of financial and technological assistance as a supplement to the domestic effort of the developing countries.

In the intervening eighteen years enormous amounts of financial aid and sustained technical assistance have been provided, but far from reducing the effects of natural disasters, development has contributed to disaster vulnerability in areas where the presence of hazards was not properly assessed.

While the link between natural disasters and development has been demonstrated repeatedly, governments and lending agencies do not yet systematically integrate the consideration of natural hazards into project preparation. Past losses and the vulnerability of infrastructure have reached such levels that in some areas development assistance consists almost entirely of disaster relief and rehabilitation. When loan proceeds are routinely programmed for reconstruction, little remains for investment in new infrastructure or economic production. Thus, recurrent disaster relief and reconstruction needs have brought about a reassessment of economic development programs in Bolivia, Colombia, Ecuador, El Salvador, Guatemala, Honduras, Nicaragua, Peru, the Paraguay River Basin, and several Caribbean island countries.

There is a growing awareness that natural hazard management is a pivotal issue of development theory and practice. The United Nations has declared the 1990s the "International Decade for Natural Disaster Reduction" (IDNDR) and calls on developing countries to participate actively in reducing disaster vulnerability. The OAS has endorsed the IDNDR and made natural hazard management a priority technical assistance area.


A key element to be addressed in this decade is the distribution of resources between disaster prevention and post-disaster efforts. Prevention, which includes structural measures (e.g., making structures more hazard-resistant) and non-structural measures (e.g., land-use restrictions), is a cost-effective means of reducing the toll on life and property. Post-disaster relief and reconstruction measures are important for humanitarian reasons, and may include improvements that are designed to prevent or mitigate future disasters. This is increasingly the case in projects funded by development financing organizations. Nevertheless, post-disaster measures are disproportionately costly for each life saved and each building reconstructed. Moreover, preventive measures in developing countries can reduce the human tragedy and the incalculable costs of lost jobs and production associated with natural disasters.

It is useful in this regard to distinguish between hazard management and disaster management. Both include the complete array of pre-event and post-event measures, but they differ in their focus. Disaster management is concerned with specific events that destroy lives and property to such an extent that international assistance is often needed. Hazard management addresses the potentially detrimental effects of all natural hazardous events, whether or not they result in a disaster; it is the more inclusive of the two terms, seeking to incorporate consideration of natural hazards in all development actions, regardless of the severity of the impact. It thus concentrates more on the analysis of hazards, the assessment of the risk they present, and the prevention and mitigation of their impact, while disaster management tends to concentrate more on preparedness, alert, rescue, relief, rehabilitation, and reconstruction.

Despite the clear economic and humanitarian advantages of prevention, it is relief and reconstruction measures that typically enjoy political appeal and financial support. Donor nations quickly offer sophisticated equipment and highly trained personnel for search and rescue missions. Politicians of a stricken nation gain more support from consoling disaster victims than from requesting taxes for the undramatic measures that would have avoided the disaster. Short-term efforts to address immediate needs usually take precedence over long-term disaster recovery and prevention activities, particularly given the visibility attached to the relief phase of disaster by the mass media. It is not surprising, therefore, to find that of all funds spent on natural hazard management in the region, more than 90 percent goes to saving lives during disasters and replacing lost investment; less than 10 percent goes to prevention before disasters.

The situation is similar with respect to science and technology. Increasingly, investment is directed toward prediction, monitoring, and alert technologies as opposed to basic information on the location, severity and probability of events-the data that provide the basis for prevention measures. A sound balance must be sought between obtaining additional scientific information and applying existing information to institute mitigation measures resting chiefly on economic and political organization and process.


From the seven years of experience the Organization of American States through its Department of Regional Development and Environment (OAS/DRDE) has had in assisting its member states with natural hazard management and reduction of vulnerability to natural disasters, several related principles have emerged:

The impact of natural hazards can be reduced. The information and methods exist to minimize the effects of even the most sudden and forceful of hazardous events and prevent them from causing a disaster. While in some cases the event itself cannot be avoided, construction measures and location decisions can save lives and prevent damage. In other cases, such as flooding, the integration of hazard mitigation measures into development planning and investment projects may make it possible to avoid the event altogether.

Hazard mitigation pays high social and economic dividends in a region with a history of natural disasters. Mitigation measures should be seen as a basic investment, fundamental to all development projects in high-risk areas, and not as a luxury that may or may not be affordable. The vulnerability of many areas of Latin America and the Caribbean to hurricanes, earthquakes, volcanic eruptions, flooding, or drought is widely recognized. Planners should not ask themselves whether these events will occur, but what may happen when they do.

Hazard management is most effective in the context of integrated development planning. Traditional single-sector planning cannot maximize the benefits of mitigation techniques and may, in fact, increase the risk exposure of people and their property. Because the traditional development project often represents an isolated intervention into complex and long-standing natural and socioeconomic processes, an advance In one sector may not be accompanied by needed change in another. When natural events subsequently exert pressure, the fruits of the project may be lost to a disaster caused by the deterioration of the natural and human environment related, in turn, to the project itself.

Integrated development planning, in contrast, means a multisectoral approach. It accounts both for a change in associated sectors that share a defined physical space and for the changing relationships between sectors as the result of an intervention. Underlying the integrated approach is the assumption that change is organic and that an initiative in one sector affects the region as a whole. In its development work the OAS applies this philosophy by preparing packages of interrelated projects that reflect a balance between investment in infrastructure, productive activities, service provision, and resource management.

Natural hazard considerations should be introduced at the earliest possible stage in the development process. If a site lies in a fault zone subject to earthquakes, that should be known before it is planned for urban development. If an area considered for an irrigation project is subject to flooding, that should be taken into consideration in the formulation of the project. As natural hazard risk is identified earlier in the planning process, fewer undesirable projects will be carried forward simply on their own momentum. Mitigation measures should be introduced early, and non-structural mitigation, the most cost-effective mechanism, requires particularly early recognition of the need for land-use restrictions. Like an environmental impact statement conducted on a project already formulated, an after-the-fact natural hazard evaluation has much less value than an evaluation conducted in time to influence the original formulation of the project.

One of the roles of technical cooperation agencies such as the OAS is the identification and preliminary formulation of investment projects which later may be funded by international lending agencies for more advanced study and implementation. It is important that technical cooperation agencies incorporate hazard considerations into their part of the development process since it becomes progressively more difficult to do so in later stages.

Use Common Sense. People know the kinds of hazards that occur in their home areas. They may not know how to quantify these dangers or the best ways to mitigate them, but they understand something must be done about them.

This book is a guide to natural hazard management in the context of integrated development planning based on the accumulated experience of the OAS. It is in no sense comprehensive, but rather is confined to the experiences of the recent past in development planning in this hemisphere. Readers should also be aware that it focuses on broad strategies and methodologies, rather than specific instructions for all possible particular cases. But it is about what has proved useful in actual field work.


Hagman, G. Prevention Better than Cure (Stockholm: Swedish Red Cross, 1984).

Office of Foreign Disaster/United States Agency 1 International Development. Disaster History Significant Data on Major Disasters Worldwide 1900-Present. July, 1989 (Washington, D.(OFDA/USAID, 1989).

World Bank. Memorandum on Recent Economic Development and Prospects of Honduras (Washington, D.C.: World Bank, 1979).

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