Robin Spence

Using High-Resolution Satellite Images for Post-Earthquake Building Damage Assessment: A Study Following the 26 January 2001 Gujarat Earthquake

Newly available optical satellite images with 1-m ground resolution such as IKONOS mean that rapid postdisaster damage assessment might be made over large areas. Such surveys could be of great value to emergency management and post-event recovery operations and have particular promise for earthquake areas, where damage distribution is often very uneven. In this paper three satellite images taken before and after the 26 January 2001 Gujarat earthquake were studied for damage assessment purposes. The images comprised a post-earthquake cover of the city of Bhuj, which was close to the epicenter, and pre- and post-earthquake cover of the city Ahmedabad. The assessment data was then compared with damage surveys actually made on-site. Three separate experiments were conducted. In the first, the satellite image of Bhuj was compared with detailed ground photos of 28 severely damaged buildings taken at about the same time as the satellite image, to investigate the levels and types of damage that can and cannot be identified. In the second experiment, the whole city center of Bhuj was damage mapped using only the satellite image. This was subsequently compared with a map produced from a building-by-building damage survey. In the third experiment, pre- and post-earthquake images for a large area of Ahmedabad were compared and totally collapsed buildings were identified. These sites were subsequently visited to confirm the accuracy of the observations. The experiment results indicate that rapid visual screening can identify areas of heavy damage and individual collapsed buildings, even when comparative cover does not exist. The need to develop a tool with direct application to support emergency response is discussed.

Sustainable development and the construction industry

Abstract The construction industry, together with the materials industries which support it, is one of the major global exploiters of natural resources, both physical and biological. The industry thus contributes very significantly to the current unsustainable development path of the global economy. This paper has two purposes. First, it attempts to identify the principal ways in which construction contributes to environmental stress, and to quantify the contribution of construction where possible. Secondly, it considers the means available to reduce these environmental impacts, through improved technology, design or changed practices; and it suggests ways in which governments can take action to promote these changes.

Mapping the conceptual design activity of interdisciplinary teams

Abstract The conceptual design phase of any project is, by its very nature, a vibrant, creative and dynamic period. It can also be disorganised with much backtracking accompanying the exchange of information between design team members. The transfer of information, ideas and opinion is critical to the development of concepts and as such, rather than being recognised as merely a component of conceptual design activity, it needs to be understood and, ultimately, managed. This paper describes an experimental workshop involving fifteen design professionals in which conceptual design activity was tracked, and subsequently mapped, in order to test and validate a tentative design framework (phase and activity model). The nature of the design progression of the various teams is captured and analysed, allowing a number of conclusions to be drawn regarding both the iterative nature of this phase of design and how teams of professionals actually design together.

Development of an earthquake loss model for Turkish catastrophe insurance

Following the devastating Kocaeli and Düzce earthquakes of August andNovember 1999, the Turkish Government was faced with an enormousfinancial burden as a result of its statutory obligation to cover the full costsof rebuilding. In order to offset this liability in the future – which has hadan adverse effect on the Governments economic programme – acompulsory earthquake insurance scheme has been introduced for allhouseholders in Turkey. A key element for successful implementation ofthis novel and ambitious programme is the transfer of the earthquake riskabsorbed by the Turkish Catastrophe Insurance Pool (TCIP) to theinternational reinsurance market. An earthquake loss model, described inthis paper, has been developed for the TCIP to serve as a basis for thedecision-making process with respect to the pricing of its insurance policy,risk control, the purchase of reinsurance, and the transfer of seismic risk.Sample results of the loss calculations are presented.

Building vulnerability and human casualty estimation for a pyroclastic flow: a model and its application to Vesuvius

Abstract Pyroclastic flows clearly present a serious threat to life for the inhabitants of settlements on the slopes of volcanoes with a history of explosive eruptions; but it is increasingly realised that buildings can provide a measure of protection to occupants trapped by such flows. One important example is Vesuvius, whose eruption history includes many events which were lethal for the inhabitants of the neighbouring Vesuvian villages. Recent computational fluid dynamics computer modelling for Vesuvius [Todesco et al., Bull. Volcanol. 64 (2002) 155–177] has enabled a realistic picture of an explosive eruption to be modelled, tracing the time-dependent development of the physical parameters of a simulated flow at a large three-dimensional mesh of points, based on assumed conditions of temperature, mass-flow rate and particle size distribution at the vent. The output includes mapping of temperature, mixture density and mixture velocity over the whole adjacent terrain. But to date this information has not been used to assess the impacts of such flows on buildings and their occupants. In the project reported in this paper, estimates of the near-ground flow parameters were used to assess the impact of a particular simulated pyroclastic flow (modelled roughly on the 1631 eruption) on the buildings and population in four of the Vesuvian villages considered most at risk. The study had five components. First, a survey of buildings and the urban environment was conducted to identify the incidence of characteristics and elements likely to affect human vulnerability, and to classify the building stock. The survey emphasised particularly the number, location and type of openings characteristic of the major classes of the local building stock. In the second part of the study, this survey formed the basis for estimates of the probable impact of the pyroclastic flow on the envelope and internal air conditions of typical buildings. In the third part, a number of distinct ways in which human casualties would occur were identified, and estimates were made of the relationship between casualty rates and environmental conditions for each casualty type. In the fourth part of the study, the assumed casualty rates were used to estimate the proportions of occupants who would be killed or seriously injured for the assumed pyroclastic flow scenario in the Vesuvian villages studied, and their distribution by distance from the vent. It was estimated that in a daytime eruption, 25 min after the start of the eruption, there would be 480 deaths and a further 190 serious injuries, for every 1000 remaining in the area. In a night-time scenario, there would be 360 deaths with a further 230 serious injuries per 1000 after the same time interval. Finally, a set of risk factors for casualties was identified, and factors were discussed and ranked for their mitigation impact in the eruption scenario. The most effective mitigation action would of course be total evacuation before the start of the eruption. But if this were not achieved, barred window openings or sealed openings to slow the ingress of hot gases, together with a reduction of the fire load, could be effective means of reducing casualty levels.

Earthquake loss estimation for Europe's historic town centres

To support decision-making on upgrading strategies of historic city centres, loss estimation techniques are needed, suitable for application to masonry buildings. This paper describes the development and application of such techniques to a case study in the Alfama District of Lisbon. The project involved a survey of 200 buildings to investigate structural features and condition, mapped using a GIS system, followed by analysis of key collapse mechanisms to define static collapse loads under horizontal forces for each building. The results, obtained in terms of earthquake ground motions likely to produce equivalent damage, led to the development of vulnerability functions for the case study, verified by comparison with functions derived from statistical analysis of world-wide damage reports and with damage reports of the 1755 Lisbon earthquake. The method is used to predict the reduction in losses achieved by the introduction of low-cost unobtrusive strengthening techniques, such as tie-rods connecting facade walls to floors and cross-walls. Cost benefit analysis, considering only structural costs, indicates that the return on the investment would be considerable.

Development and verification of a generic framework for conceptual design

Abstract The rapid and dynamic information and knowledge transfer between designers during the conceptual phase of building projects can result in disorganised behaviour within the team. Team members can become frustrated by the lack of a common understanding of the manner in which the design activity is being performed and the direction in which the process is progressing. Evidence suggests that design teams are better equipped to undertake design activity when in possession of a general programme of events or activities through which they are likely to pass than when no such structuring concept is held. This paper describes the development and verification of a structured framework, which has been generated to aid and support the interdisciplinary team in undertaking conceptual design.

Risk and regulation: can improved government action reduce the impacts of natural disasters?

From an examination of national policies for risk mitigation, the paper asks what types of laws are successful and should be more widely adopted, and what does not work. Three types of regulations are considered: (1) regulations for constructing new buildings and code enforcement; (2) regulations for intervening in/upgrading the existing building stock; and (3) regulation of the insurance industry. When applied, improved codes can substantially reduce the impacts of natural disasters. However, unnecessary complexity is shown to compromise implementation and enforcement. The widespread destruction of buildings in the earthquakes of Kocaeli, Turkey, in 1999 and Gujarat, India, in 2001 was not due to inadequate codes. Destruction occurred because codes were not generally adopted. Improving the application and enforcement of codes in developing countries are necessary key measures. For the strengthening of existing substandard buildings, some regulations exist and some successful programmes of evaluation and strengthening are in progress. However, lessons from the US experience indicate legislation is needed to back such programmes, and further incentives for action are needed. Several national insurance schemes for natural catastrophe losses (US programmes for flood, New Zealand programmes for earthquake, and French programmes for all catastrophic natural hazards) have considerable potential to stimulate mitigation activity. Ultimately, coercion by government is only part of the answer. The success of any government action depends equally on the development in society of a ‘safety culture’ in which citizens both understand the risks they face and are prepared to participate in the management of them.

Risk assessment of residential buildings for an eruption of Furnas Volcano, São Miguel, the Azores

This paper presents the results of a study of the risks to human settlements of a future eruption of the Furnas Volcano in the Azores. It makes use of previous geological studies to estimate the likely impact of the volcanic hazards on the surrounding settlements, given an eruption comparable with the last major eruption in the island in 1630; it presents the results of a comprehensive building-by-building survey of the settlements at risk to determine the exposure of the residential building stock to these hazards; and it uses data from recent experience of volcanic eruptions elsewhere to estimate the vulnerability of the buildings to each hazard and the likely scale of human casualties and building damage. The paper concludes with some recommendations for preparedness and protective measures which could be taken before an eruption to reduce the risk of human casualties from roof and building collapses. Principal among these are recommendations for strengthening the lateral load resistance of buildings built with the traditional vernacular techniques to better resist groundshaking during eruptions and earthquakes; upgrading local building code requirements with view to increasing the live load resistance of roofs, to levels similar to those applied in areas of heavy snowfalls, to prevent roof collapse from tephra loading. Other preparedness measures are also discussed with respect to volcanic earthquakes, volcanic bomb impact, pyroclastic flows and tephra falls. Many aspects of this paper are relevant to other volcanic areas around the world.

A Comprehensive Analysis of Building Damage in the 12 January 2010 Mw7 Haiti Earthquake Using High-Resolution Satellite-and Aerial Imagery

The paper provides an account of how three key relief organizations worked together after the devastating Haiti earthquake to produce the first damage assessment based mainly on the use of remotely-sensed imagery. This assessment was jointly conducted by the World Bank (WB), the United Nations Institute for Training and Research (UNITAR) Operational Satellite Applications Programme (UNOSAT), and the European Commission’s Joint Research Centre (JRC). This paper discusses the data sources used for the assessment, the methodologies employed to evaluate building damage, and a set of independent studies to validate the final damage results. Finally, a vision of the role of remote sensing technologies in future disasters is presented that serves as a road map for methodological improvements.