Geotechnical hazard representation for seismic risk analysis

Seismic risk analysis, either deterministic or probabilistic, along with the use of a GIS-environment to represent the results, are helpful tools to support the decision making for planning and prioritizing seismic risk management strategies. This paper focuses on the importance of an appropriate geotechnical hazard representation within a seismic risk analysis process. An overview of alternative methods for geotechnical zonation available in the literature, with a different level of refinement depending on the information available, is provided. It is worth noting that in such methods, the definition of the site effect amplifications does not account for the characteristics of the built environment, affecting the soil-structure interaction. Alternative methods able to account for either the soil conditions and the characteristics of the built environment have been recently proposed and are herein discussed. Within a framework for seismic risk analysis, different formulations would thus derive depending on both the intensity measure and the vulnerability approach adopted. In conclusion, an immediate visualization of the importance of the geotechnical hazard evaluation within a seismic risk analysis is provided in terms of the variation of the expected damage and consequence distribution with reference to a case-stud

Evaluating desktop methods for assessing liquefaction-induced damage to infrastructure for the insurance sector

The current method used by insurance catastrophe models to account for liquefaction simply applies a factor to shaking-induced losses based on liquefaction susceptibility. There is a need for more sophisticated methods but they must be compatible with the data and resource constraints that insurers have to work with. This study compares five models: liquefaction potential index (LPI) calculated from shear-wave velocity; two implementations of the HAZUS software methodology; and two models based on USGS remote sensing data. Data from the September 2010 and February 2011 Canterbury (New Zealand) earthquakes is used to compare observed liquefaction occurrences to predictions from these models using binary classification performance measures. The analysis shows that the best performing model is LPI although the correlation with observations is only moderate and statistical techniques for binary classification models indicate that the model is biased towards positive predictions of liquefaction occurrence

Seismic performance of buried electrical cables: evidence-based repair rates and fragility functions

The fragility of buried electrical cables is often neglected in earthquakes but significant damage to cables was observed during the 2010–2011 Canterbury earthquake sequence in New Zealand. This study estimates Poisson repair rates, similar to those in existence for pipelines, using damage data retrieved from part of the electric power distribution network in the city of Christchurch. The functions have been developed separately for four seismic hazard zones: no liquefaction, all liquefaction effects, liquefaction-induced settlement only, and liquefaction-induced lateral spread. In each zone six different intensity measures (IMs) are tested, including peak ground velocity as a measure of ground shaking and five metrics of permanent ground deformation: vertical differential, horizontal, maximum, vector mean and geometric mean. The analysis confirms that the vulnerability of buried cables is influenced more by liquefaction than by ground shaking, and that lateral spread causes more damage than settlement alone. In areas where lateral spreading is observed, the geometric mean permanent ground deformation is identified as the best performing IM across all zones when considering both variance explained and uncertainty. In areas where only settlement is observed, there is only a moderate correlation between repair rate and vertical differential permanent ground deformation but the estimated model error is relatively small and so the model may be acceptable. In general, repair rates in the zone where no liquefaction occurred are very low and it is possible that repairs present in this area result from misclassification of hazard observations, either in the raw data or due to the approximations of the geospatial analysis. Along with hazard intensity, insulation material is identified as a critical factor influencing cable fragility, with paper-insulated lead covered armoured cables experiencing considerably higher repair rates than cross-linked polyethylene cables. The analysis shows no trend between cable age and repair rates and the differences in repair rates between conducting materials is shown not to be significant. In addition to repair rate functions, an example of a fragility curve suite for cables is presented, which may be more useful for analysis of network connectivity where cable functionality is of more interest than the number of repairs. These functions are one of the first to be produced for the prediction of damage to buried cables

The vulnerability assessment of current buildings by a macroseismic approach derived from the EMS-98 scale

A hierarchical family of Damage Probability Matrices (DPM) has been derived in this paper from the ones implicitly contained in the EMS-98 Macroseismic Scale for 6 vulnerability classes. To this aim the linguistic definitions provided by the scale, and the associated fuzzy sub-sets of the percentage of buildings, have been completed according to reliable hypotheses. A parametric representation of the corresponding cumulative probability distributions is moreover provided, through a unique parameter: a vulnerability index variable in the range from 0 to 1 and independent of the macroseismic intensity. Finally, an innovative macroseismic approach allowing the vulnerability analysis of building typologies is defined within the European Macroseismic Scale (EMS-98) and qualitatively related to the vulnerability classes. Bayes’ theorem allows the upgrading of the frequencies when further data about the built-environment or specific properties of the buildings are available, allowing the identification of a different behaviours with respect to the one generally considered for the typology. Fuzzy measures of any damage function can be derived, using parametric or nonparametric damage probability matrices. For every result of the seismic analysis, the procedure allows supply to the user of the final uncertainty connected with the aforementioned fuzzy relation between the probability of the damage grade, the macroseismic intensity and the vulnerability classes

New Zealand contributions to the global earthquake model’s earthquake consequences database (GEMECD)

The Global Earthquake Model’s (GEM) Earthquake Consequences Database (GEMECD) aims to develop, for the first time, a standardised framework for collecting and collating geocoded consequence data induced by primary and secondary seismic hazards to different types of buildings, critical facilities, infrastructure and population, and relate this data to estimated ground motion intensity via the USGS ShakeMap Atlas. New Zealand is a partner of the GEMECD consortium and to-date has contributed with 7 events to the database, of which 4 are localised in the South Pacific area (Newcastle 1989; Luzon 1990; South of Java 2006 and Samoa Islands 2009) and 3 are NZ-specific events (Edgecumbe 1987; Darfield 2010 and Christchurch 2011). This contribution to GEMECD represented a unique opportunity for collating, comparing and reviewing existing damage datasets and harmonising them into a common, openly accessible and standardised database, from where the seismic performance of New Zealand buildings can be comparatively assessed. This paper firstly provides an overview of the GEMECD database structure, including taxonomies and guidelines to collect and report on earthquake-induced consequence data. Secondly, the paper presents a summary of the studies implemented for the 7 events, with particular focus on the Darfield (2010) and Christchurch (2011) earthquakes. Finally, examples of specific outcomes and potentials for NZ from using and processing GEMECD are presented, including: 1) the rationale for adopting the GEM taxonomy in NZ and any need for introducing NZ-specific attributes; 2) a complete overview of the building typological distribution in the Christchurch CBD prior to the Canterbury earthquakes and 3) some initial correlations between the level and extent of earthquake-induced physical damage to buildings, building safety/accessibility issues and the induced human casualtie

Damage and vulnerability analysis of URM churches after the Canterbury earthquake sequence 2010-2011

The Canterbury earthquake sequence, in 2010-2011, has highlighted once again the vulnerability ofmonumental structures, in particular churches, and the importance of reducing their risk from an economic, cultural and social point of view. Within this context, detailed analysis is reported of the earthquake-induced damage to a stock of 48 unreinforcedmasonry churches located in the Canterbury Region and the vulnerability analysis of a wider stock of 293 churches located all around New Zealand. New tools were developed forthe assessmentof New Zealand churches. The computation of a new damage grade isproposed, assessed as a proper combination of the damage level to each macroelement, as a step towards the definition of a New Zealand specific damage survey form. Several vulnerability indicators were selected, which are related to easily detectable structural details and geometric dimensions. The collection of such data for the larger set of churches (293) constitutes a useful basis for evaluating the potential impact of future seismic event

The role of architectural design for rheumatic patients' wellbeing: the point of view of Environmental Psychology

Rheumatic diseases (RD) are among the most frequent disorders in the population and the major causes of chronic pain and disability. The resulting consequences are catastrophic, leading to a significant socio-economic burden, which includes significant reductions in quality of life (QoL) and limitations in regular work and daily activities of patients. In spite of this, rheumatic diseases are often misunderstood or diagnosed late, probably due to their characteristics of silent diseases, sometimes unrecognizable to unaffected or unskilled people. Actually, it is surprising that, despite their consequences on QoL and on individual impact, rheumatic diseases are underestimated by the public opinion, which is probably more attracted by other major diseases causing death. This silent perception can even be seen in some among the most recent psycho-social approaches to population needs in the fields of Health Psychology and Environmental Psychology. The latter, also known as Architectural Psychology, is a branch of Psychology that analyses the effects of the built environment on humans, including those affected by diseases. Paradoxically, in many cases, some components of the environments created to protect individuals and/or the population may represent barriers and subsequently causes of disability and suffering in patients with rheumatic diseases. In order to increase awareness about this particular aspect of social life, HEMOVE Onlus, a non-profit association, has promoted the creation of a multidisciplinary Task Group, which included mainly rheumatologists, psychologists and architects, with the aim of applying also for the benefit of rheumatic patients the most modern technical skills available in the context of Environmental Psychology, including in particular design and information technology