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We investigate the use of multiepoch airborne and terrestrial lidar to detect and measure ground displacements of sufficient magnitude to damage buried pipelines and other water system facilities that might result, for example, from earthquake or rainfall-induced landslides. Lidar scans are performed at three sites with coincident measurements by total station surveying. Relative horizontal accuracy is evaluated by measurements of lateral dimensions of well defined objects such as buildings and tanks; we find misfits ranging from approximately 5 to 12 cm, which is consistent with previous work. The bias and dispersion of lidar elevation measurements, relative to total station surveying, is assessed at two sites: (1) a power plant site (PP2) with vegetated steeply sloping terrain; and (2) a relatively flat and unvegetated site before and after trenching operations were performed. At PP2, airborne lidar showed minimal elevation bias and a standard deviation of approximately 70 cm, whereas terrestrial lidar did not produce useful results due to beam divergence issues and inadequate sampling of the study region. At the trench site, airborne lidar showed minimal elevation bias and reduced standard deviation relative to PP2 (6-20 cm), whereas terrestrial lidar was nearly unbiased with very low dispersion (4-6 cm). Pre- and posttrench bias-adjusted normalized residuals showed minimal to negligible correlation, but elevation change was affected by relative bias between epochs. The mean of elevation change bias essentially matches the difference in means of pre- and posttrench elevation bias, whereas elevation change standard deviation is sensitive to the dispersion of individual epoch elevations and their correlation coefficient. The observed lidar bias and standard deviations enable reliable detection of damaging ground displacements for some pipelines types (e.g., welded steel) but not all (e.g., concrete with unwelded, mortared joints). DOI: 10.1061/(ASCE)0733-9453(2009)135:3(113) CE Database subject headings: Aerial surveys; Differential settlement; Land surveys; Landslides; Lasers; Water pipelines.

This paper introduces the multihazard optimization-based probabilistic scenario (multihazard OPS) method to create an ensemble of multihazard scenarios that can be used for efficient evaluation of spatially distributed infrastructure. Each multihazard scenario is a map depicting a possible realization of the co-occurring multiple hazard effects associated with a single earthquake, including ground motion intensity contours, liquefaction potential contours, and locations of surface fault rupture. Together, when the small set of multihazard scenarios are combined with their computed weights, they represent the probabilistic hazard in a way that captures spatial correlation, includes multiple hazards, and is computationally efficient. In demonstrating the method for Los Angeles, California, we find a set of 350 multihazard scenarios matches the regional hazard and damage with errors small enough for most practical purposes. Further reduction is possible depending on the desired tradeoff between acceptable errors and computational efficiency. A sensitivity analysis suggests it is important to consider each hazard type in determining the multihazard scenarios, although the outcome is not sensitive to the precision of the weights. [ABSTRACT FROM AUTHOR]

The seismic performance of Balboa Boulevard during the 1994 MW 6.7 Northridge earthquake was examined through nonlinear deformation analyses (NDAs) using advanced tools to (1) investigate the failure mechanism leading to ground deformations at this site; (2) evaluate the accuracy of the adopted analysis methods, engineering procedures, and state-of-the-art tools to reasonably estimate horizontal ground displacements; and (3) identify key factors and parameters contributing to earthquake-induced ground deformations at this site. One-dimensional (1D) liquefaction vulnerability indexes (LVIs) and permanent displacements using Newmark sliding block analyses were also estimated and compared against ground deformations observed after the earthquake. The geotechnical characterization of Balboa Boulevard was assessed based on field and laboratory data obtained from two investigation campaigns. Transitional probability geostatistics were used to develop stratigraphic models that capture the heterogeneity and the spatial variability patterns of sand-like and clay-like soils present at this site. The stratigraphic models were implemented in the finite difference software FLAC and the behavior of sand-like and clay-like soils simulated using the PM4Sand and PM4Silt constitutive models, respectively. Sensitivity analyses were performed to address uncertainties associated with the spatial variability of soils, input ground motions, the proportion of sand-like and clay-like soils within the soil deposit, and the strength properties of these materials. Results from NDAs suggest that a compounded effect of both liquefaction of sand-like soils and cyclic softening of clay-like soils led to the excessive ground deformations at Balboa Boulevard. This study sheds light on the importance of using appropriate engineering procedures and numerical modeling protocols in the prediction of deformation patterns, the selection of key input parameters, as well as the applicability of LVIs in complex sites. [ABSTRACT FROM AUTHOR]

Infrastructure includes building and lifeline systems essential to supporting community resilience through functionality and operability. A hazard attack (e.g., earthquake or hurricane) can damage systems and abruptly drop their functionality and operability. Operability is a measure of the infrastructure system's support for community resilience through the ability to adapt and transform to restore basic services for users (an operational level allowing social institutions to provide services), which can be achieved before all system repairs are made. Functionality is a measure of the infrastructure system's resilience and is not fully restored until all system repairs are completed and operational restrictions removed. Currently, the literature describes both measures as "functionality," but the dual application of the same term causes confusion and miscommunication. As a result, "operability" is proposed as an important expression also needed to properly measure infrastructure resilience. Full operability is achieved at a functional level when all basic services are restored. This technical note offers practical definitions for functionality and operability within a resilience context and identifies basic service categories to use when analyzing infrastructure system resilience. [ABSTRACT FROM AUTHOR]