車載画像を用いた都市の4次元モデリング

Tohoku University岡谷貴之課

Methodology for an effective risk assessment of urban areas: progress and first results of the merisur project

The progress and results the MERISUR, Methodology for an Effective RISk assessment of URban areas, are presented. This project aims at developing an effective methodology for urban seismic risk assessment that provides solutions to some deficiencies detected after recent damaging events worldwide, including risk mitigation actions based on benefit/cost ratios. In a fisrt stage, the hazard and vulnerability models are developed and improved. A procedure to determine the hazard-controlling seismogenic fault, contsistent with different probability levels, is established. Methods to include active faults as individual sources and to consider near filed effects that significantly amplify ground motions are proposed. A more complete description of seismic vulnerability encompassing structural, non-structural components is accomplished. Vulnerability modifiers to incorporate effects or urban parameters on vulnerability classes are also quantified. A distinction is also made between damage to structural and non-structural building elements. For this purpose, a pushover analysis is specifically carried out to model building response and damage trends on non-structural elements. This gives the primary damage. In addition, the area covered by the resulting debris is also estimated both in inner spaces (within the building) and in the outer space (public roads and streets). In this way, a volume of debris will be associated to each area unit of the city, and the potential damage to persons and elements exposed, such as urban furniture and vehicles, will be assessed. This constitutes the secondary damage. A static level of occupation (building, urban furniture, etc.) and a dynamic level of occupation (persons, vehicles) will be assigned to each area unit of the city, hereby defining the exposure in time and space. Earthquake losses related to primary damage of building components and to secondary damage (such as urban furniture and vehicles) will be also assessed. Cost/benefit ratios between ex ante risk mitigation measurements will be developed in order to decide whether risk transfer or risk retention is preferable for different risk scenarios. This analysis will confer effectiveness to the results of a seismic risk study. Overall, the estimate of earthquake losses and cost/benefit ratios are topics with little presence in the scientific literature concerning damaging earthquakes in Spain. Thus, the results of this study will provide effective solutions to the challenge to society tackled in this proposal

Earthquakes, Tsunamis and Nuclear Risks

Environmental Managemen

Relative seismic and tsunami risk assessment for Stromboli Island (Italy)

An innovative method of estimating the relative risk of buildings exposed to seismic and tsunami hazards in volcanic islands is applied to Stromboli (Italy), a well-known stratovolcano affected by moderate earthquakes and mass-flow-induced tsunamis. The method uses a pre-existing quali-quantitative analysis to assess the relative risk indices of buildings, which provide comparative results useful for prioritisation purposes, in combination with a historical-geographical settlement analysis consistent with the ‘territorialist’ approach to the urban and regional planning and design. The quali-quantitative analysis is based on a new proposed survey-sheet model, useful to collect building information necessary for the relative risk estimation, whereas the historical-geographical investigation is based on the multi-temporal comparison of aerial and satellite images. The proposal to combine two consolidated methods represents an innovation in estimating relative risk. Considering that Stromboli Island had never been subjected to similar analyses, the results of the relative seismic risk assessment are novel and moreover identify buildings with a fairly-low and spatially-uniform relative risk. The results of the relative tsunami risk assessment are consistent with results of similar past studies, identifying buildings with a higher relative risk index on the northern coast of the island. The combined use of a building-by-building survey with a multi-temporal analysis of settlements allows obtaining a higher detail than previously available for the region. If adequately modified, the proposed combination of methods allows assessing relative risk also considering other geo-environmental hazards and their cascading effects, in a multi-hazard risk assessment perspective

Recommendations for the quantitative analysis of landslide risk

This paper presents recommended methodologies for the quantitative analysis of landslide hazard, vulnerability and risk at different spatial scales (site-specific, local, regional and national), as well as for the verification and validation of the results. The methodologies described focus on the evaluation of the probabilities of occurrence of different landslide types with certain characteristics. Methods used to determine the spatial distribution of landslide intensity, the characterisation of the elements at risk, the assessment of the potential degree of damage and the quantification of the vulnerability of the elements at risk, and those used to perform the quantitative risk analysis are also described. The paper is intended for use by scientists and practising engineers, geologists and other landslide experts.JRC.H.5-Land Resources Managemen

Quantifying near-field and off-fault deformation patterns of the 1992 M_w 7.3 Landers earthquake

Coseismic surface deformation in large earthquakes is typically measured using field mapping and with a range of geodetic methods (e.g., InSAR, lidar differencing, and GPS). Current methods, however, either fail to capture patterns of near-field coseismic surface deformation or lack preevent data. Consequently, the characteristics of off-fault deformation and the parameters that control it remain poorly understood. We develop a standardized method to fully measure the surface, near-field, coseismic deformation patterns at high resolution using the COSI-Corr program by correlating pairs of aerial photographs taken before and after the 1992 M_w 7.3 Landers earthquake. COSI-Corr offers the advantage of measuring displacement across the entire zone of surface deformation and over a wider aperture than that available to field geologists. For the Landers earthquake, our measured displacements are systematically larger than the field measurements, indicating the presence of off-fault deformation. We show that 46% of the total surface displacement occurred as off-fault deformation, over a mean deformation width of 154 m. The magnitude and width of off-fault deformation along the rupture is primarily controlled by the macroscopic structural complexity of the fault system, with a weak correlation with the type of near-surface materials through which the rupture propagated. Both the magnitude and width of distributed deformation are largest in stepovers, bends, and at the southern termination of the surface rupture. We find that slip along the surface rupture exhibits a consistent degree of variability at all observable length scales and that the slip distribution is self-affine fractal with dimension of 1.56