The QuakeSim Project: Web Services for Managing Geophysical Data and Applications

We describe our distributed systems research efforts to build the “cyberinfrastructure” components that constitute a geophysical Grid, or more accurately, a Grid of Grids. Service-oriented computing principles are used to build a distributed infrastructure of Web accessible components for accessing data and scientific applications. Our data services fall into two major categories: Archival, database-backed services based around Geographical Information System (GIS) standards from the Open Geospatial Consortium, and streaming services that can be used to filter and route real-time data sources such as Global Positioning System data streams. Execution support services include application execution management services and services for transferring remote files. These data and execution service families are bound together through metadata information and workflow services for service orchestration. Users may access the system through the QuakeSim scientific Web portal, which is built using a portlet component approach.     

Optimal cost‐effective topology of column bearings for reducing vertical acceleration demands in multistory base‐isolated buildings

Base‐isolation is regarded as one of the most effective methods for protecting the structural and nonstructural building elements from design level horizontal earthquake ground shaking. However, base‐isolation as currently practiced does not offer unlimited protection for these buildings, especially when the ground shaking includes a strong vertical component. The vulnerability of nonstructural systems in a base‐isolated building was made evident during recent shake table testing of a full‐scale five‐story base‐isolated steel moment frame where nonstructural system damage was observed following tests including vertical excitation. Past research efforts have attempted to achieve 3D isolation of buildings and nuclear structures by concentrating both the horizontal and vertical flexibility at the base of the building that are either quite limited or not economically viable. An approach whereby the vertical flexibility is distributed up the height of the building superstructure to passively reduce vertical acceleration demands in base‐isolated buildings is presented. The vertical flexibility is achieved by placing laterally restrained elastomeric ‘column’ bearings at one or more floor levels along the height of the building. To broadly investigate the efficacy of the vertically distributed flexibility concept and the trade‐off between mitigation and cost, a multi‐objective optimization study was conducted considering 3‐story, 9‐story, and 20‐story archetype buildings that aimed to minimize the median peak vertical floor acceleration demands and to minimize the direct cost of column bearings. Based on the results of the optimization study, a practical rule for determining the number of levels and locations of column bearings is proposed and evaluated. Copyright © 2013 John Wiley & Sons, Ltd.     

Fuzzy rule based seismic risk assessment of one-story precast industrial buildings

Efficient tools capable of using uncertain data to produce fast and approximate results are more practical in rapid decision-making applications when compared to conventional methods. From this point of view, this study introduces a risk assessment model for one-story precast industrial buildings by fuzzy logic which builds a bridge between uncertainty and precision. The input, output and relations of the fuzzy based risk assessment model(FBRAM) were determined by reference buildings. The Monte Carlo simulation method was used to handle uncertainties associated with the structural characteristics of the reference buildings. Section dimension, longitudinal reinforcement ratio, column height related to building elevation, confinement ratio and seismic hazard are regarded as input and the plastic demand ratio is considered as the output parameter by the mathematical formulation of strength and deformation capacity of the buildings. The supervised learning method was used to determine the membership function of fuzzy sets. Fuzzy rules of FBRAM were constructed from Monte Carlo simulation by mapping of inputs and output. FBRAM was evaluated by a group of simulated buildings and two existing precast industrial buildings. Comparisons have shown significant agreement with analytical model results in both cases. Consequently, it is anticipated that the proposed model can be used for the seismic risk mitigation of precast buildings.     

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) in an urban traffic site in Erzurum,Turkey

This study presents daily and seasonal variations of PAH concentrations in Erzurum atmosphere in summer season of 2008 and in winter seasons of 2008 and 2009. Sampling location at Erzurum urban center was selected to represent the effects of traffic (University junction). 18 PAH compounds were analyzed by GC–MS. Average total PAH concentration (gas + particulate) of 18 PAH compounds were measured during 2008 winter (431 ngm^?3) and summer (103 ngm^?3) seasons at the University junction. Daily and seasonal variations of PAH compounds were investigated and compared with other urban centers in the literature. Multiple linear regression and artificial neural network (ANN) models were constructed to determine the impacts of meteorological parameters on measured individual PAH concentrations. Results of the multiple linear regression and ANN models indicated that wind speed, wind direction and intensity of total solar radiation were the most significant factors for the measured concentrations of PAH compounds.     

Exploration of S-wave velocity profiles at strong motion stations in Eskisehir,Turkey, using microtremor phase velocity and S-wave amplification

We have explored 1D S-wave velocity profiles of shallow and deep soil layers over a basement at strong motion stations in Eskisehir Province, Turkey. Microtremor array explorations were conducted at eight strong motion stations in the area to know shallow 1D S-wave velocity models. Rayleigh wave phase velocity at a frequency range from 3 to 30 Hz was estimated with the spatial autocorrelation analysis of array records of vertical microtremors at each station. Individual phase velocity was inverted to a shallow S-wave velocity profile. Low-velocity layers were identified at the stations in the basin. Site amplification factors from S-wave parts of earthquake records that had been estimated at the strong motion stations by Yamanaka et al. (2017) were inverted to the S-wave velocities and Q-values of the sedimentary layers. The depths to the basement with an S-wave velocity of 2.2 km/s are about 1 km in the central part of the basin, while the basement becomes shallow as 0.3 km in the marginal part of the basin. We finally discussed the effects of the shallow and deep sedimentary layers on the 1D S-wave amplification characteristics using the revealed profiles. It is found that the shallow soil layers have no significant effects in the amplification at a frequency range lower than 3 Hz in the area.     

A statistical assessment on global drift ratio demands of mid-rise RC buildings using code-compatible real ground motion records

Over the past 20 years, significant socio-economic losses have been encountered in Turkey due to several moderate to large earthquakes. The studies published after the earthquakes concurringly emphasized that multistory reinforced concrete (RC) buildings, mostly 3–7 story ones, collapsed or were heavily damaged as a result of inadequate seismic performance. Global drift ratio demands are mostly used as a representative quantity for determining the behavior of structures when subjected to earthquakes. In this study, three representative mid-rise RC buildings are analyzed by nonlinear time history analysis using code-compatible real ground motion record sets and the calculated global drift ratio demands of these buildings are statistically evaluated. Ground motion record sets compatible with the design spectrum defined for local soil classes in the Turkish Earthquake Code (TEC-2007) are used for the analyses. In order to evaluate the effect of the number of ground motions on drift ratio demands, five different ground motion record sets with 7, 11 and 15 ground motion records are used separately for each local soil class. Results of this study indicate that (1) the dispersion of global drift ratio demands calculated for individual ground motion records in record sets is high, (2) local soil class has no significant effect on dispersion. However, dispersion increases in a direct proportion to the number of ground motion records in a record set, (3) the mean of global drift ratio demands calculated for different ground motion record sets may differ although they are compatible with the same design spectrum, (4) the mean of the drift demands obtained from different ground motion record sets compatible with a particular design spectrum can be accepted as simply random samples of the same population at 95% confidence level.     

Analysis of dam-induced cyclic patterns on river flow dynamics

This paper investigates the impact of the Hungry Horse Dam on streamflow dynamics in the South Fork of the Flathead River, Montana, USA. To this end, pre- and post-dam periods of raw and naturalized streamflow data were analysed. Pettitt’s change point analysis indicated a significant change point in streamflow dynamics due to dam construction. Complexities in the pre- and post-dam periods were evaluated by sample and multi-scale entropy analyses, and the entropies of the post-dam period were found to be higher than those of the pre-dam period. Possible reasons for this, unrelated to the natural hydrological cycle caused by the dam, were analysed using wavelet analyses. The wavelet analyses showed a clear change in the phase relationship between precipitation and streamflow. Finally, weak positive trends found in the hydrological variables indicated the effects of human activities (e.g. dam construction). The results also revealed distorted lead times, which can improve the streamflow forecasts for different lead times.     

Mathematical modelling of a potential tsunami associated with a late glacial submarine landslide in the Sea of Marmara

Potential tsunami waves were modelled on the basis of the morphology and geological setting of a late glacial submarine landslide localized in the north-eastern sector of the Sea of Marmara, using a three-dimensional algorithm with the purpose of assessing the future risk of tsunamogenic landslides in the region. The landslide occurred off the Tuzla Peninsula on the north-eastern slope of the Ç?narc?k Basin, the easternmost of the three deep Marmara basins. The mass movement appears to be related to the Main Marmara Fault that passes below the toe of the failed mass. Observations from earlier manned submersible dives suggest that the initiation of the slide was facilitated by secondary faults associated with the Hercynian orogeny and involved Palaeozoic shales dipping southwards towards the deep basin. Radiocarbon dating of core material, together with the well-dated Marmara sapropel above the chaotically mixed landslide surface, reveal that the latest landslide event occurred about 17 ¹⁴C ka b.p. The uppermost scar of the landslide is found at 250 m and its toe at about 1,200 m below the present sea level. At the time of the slide, the Marmara Sea Basin was lacustrine, with its water level at ?85 m. In plan view the landslide has a distinctively triangular shape and the lateral extent of its toe is about 10 km. Multibeam bathymetric data indicate that the sliding motion probably occurred in two phases: a slower phase affecting the eastern part, characterized by an undulating surface, and a more rapid phase affecting the western part that possibly created tsunami waves. In the seismic sections, older failed slide masses can be clearly identified; these were probably displaced during marine isotopic stage 6 (～127–160 ka b.p.). The front of this buried material is located more than 1.5 km further south of the fault. We used a three-dimensional, Green’s function-based potential theory approach, rather than shallow-water equations commonly used in conventional tsunami simulations. The solution algorithm is based on a source-sink formulation and an integral equation. The results indicate that the maximum height of the tsunami in the Ç?narc?k Basin could have reached about half the average thickness of the sliding mass over a lateral extent of 7 km. Assuming an average thickness of 30 m for the landslide, and considering that the water level at 17 ka b.p. was at about ?85 m, the modelling shows that the maximum wave height generated by the slide would have been about 15–17 m.