Seismic damage assessment based on regional synthetic ground motion dataset: a case study for Erzincan,Turkey

Estimation of seismic losses is a fundamental step in risk mitigation in urban regions. Structural damage patterns depend on the regional seismic properties and the local building vulnerability. In this study, a framework for seismic damage estimation is proposed where the local building fragilities are modeled based on a set of simulated ground motions in the region of interest. For this purpose, first, ground motion records are simulated for a set of scenario events using stochastic finite-fault methodology. Then, existing building stock is classified into specific building types represented with equivalent single-degree-of-freedom models. The response statistics of these models are evaluated through nonlinear time history analysis with the simulated ground motions. Fragility curves for the classified structural types are derived and discussed. The study area is Erzincan (Turkey), which is located on a pull-apart basin underlain by soft sediments in the conjunction of three active faults as right-lateral North Anatolian Fault, left-lateral North East Anatolian Fault, and left-lateral Ovacik Fault. Erzincan city center experienced devastating earthquakes in the past including the December 27, 1939 (Ms = 8.0) and the March 13, 1992 (Mw?=?6.6) events. The application of the proposed method is performed to estimate the spatial distribution of the damage after the 1992 event. The estimated results are compared against the corresponding observed damage levels yielding a reasonable match in between. After the validation exercise, a potential scenario event of Mw?=?7.0 is simulated in the study region. The corresponding damage distribution indicates a significant risk within the urban area.     

Stresses from linearly distributed pressures over rectangular areas

This paper presents a general algebraical formula to determine the vertical stresses resulting from a linearly distributed surface pressure resting on an elastic medium. This problem and its various derivations has received considerable attention because of its applications in foundation engineering [1–5]. The equation presented in this paper has been determined by the integration of the Boussinesq [6] equation with respect to the general surface function of a linearly distributed loading regime. The equation can be applied to the case of an optimally designed rectangular footing subjected to biaxial bending. Unlike the current design formulae [1–7], it provides the flexibility of having various contact pressures at each of the four corners of the rectangular area. This may enable more accurate design procedures for pad foundations in the future. This paper explains the validity of the new formula by comparing its results with those produced by classical methods. It shows how it can be applied to determine the vertical stress distributions resulting from all types of linearly distributed surface pressures which occupy a rectangular area on an elastic mass. Copyright © 2000 John Wiley & Sons, Ltd.     

The 2014 seismic hazard model of the Middle East: overview and results

The Earthquake Model of Middle East (EMME) Project aimed to develop regional scale seismic hazard and risk models uniformly throughout a region extending from the Eastern Mediterranean in the west to the Himalayas in the east and from the Gulf of Oman in the south to the Greater Caucasus in the North; a region which has been continuously devastated by large earthquakes throughout the history. The 2014 Seismic Hazard Model of Middle East (EMME-SHM14) was developed with the contribution of several institutions from ten countries. The present paper summarizes the efforts towards building a homogeneous seismic hazard model of the region and highlights some of the main results of this model. An important aim of the project was to transparently communicate the data and methods used and to obtain reproducible results. By doing so, the use of the model and results will be accessible by a wide community, further support the mitigation of seismic risks in the region and facilitate future improvements to the seismic hazard model. To this end all data, results and methods used are made available through the web-portal of the European Facilities for Earthquake Hazard and Risk (www.efehr.org).     

沟底膜孔灌水条件下土壤水入渗规律的数值模拟

以土壤水动力学原理为基础,研究了沟底膜孔灌水条件下土壤水分运动规律,建立了二维入渗模型。对模型检验表明,试验实测数据与模型计算值吻合较好,说明所建立的模型是可行的。     

Intrinsic and Scattering Seismic Attenuation in Southwestern Anatolia

The intrinsic dissipation and scattering attenuation in southwestern (SW) Anatolia, which is a tectonically active region, is studied using the coda waves. First the coda quality factor (Q_c) assuming single scattering is estimated from the slope of the coda-wave amplitude decay. Then the Multiple Lapse Time Window (MLTW) analysis is performed with a uniform earth model. Three non-overlapping temporal data windows are used to calculate the scattered seismic energy densities against the source-receiver distances, which, in turn, are used to calculate separate estimates of the intrinsic and scattering factors. In order to explore the frequency dependency, the observed seismograms are band pass-filtered at the center frequencies of 0.75, 1.5, 3.0, 6.0 and 12.0. The scattering attenuation (Q_s⁻¹) is found lower than the intrinsic attenuation (Q_i⁻¹) at all frequencies except at 0.75 Hz where the opposite is observed. Overall the intrinsic attenuation dominates over the scattering attenuation in the SW Anatolia region. The integrated energy curves obtained for the first energy window (i.e., 0–15 s) are somewhat irregular with distance while the second (i.e., 15–30 s) and third (i.e., 30–45 s) data windows exhibit more regular change with distance at most frequencies. The seismic albedo B₀ is determined as 0.61 at 0.75 Hz and 0.34 at 12.0 Hz while the total attenuation factor denoted by L_e⁻¹ changes in the range 0.034–0.017. For the source-station range 20–180 km considered the scattering attenuation is found strongly frequency dependent given by the power law Q_s⁻¹ = 0.010*f^−1.508. The same relations for Q_i⁻¹, Q_t⁻¹ (total), Q_c⁻¹ and (expected) hold as Q_i⁻¹ = 0.0090*f^−1.17, Q_t⁻¹ = 0.019*f^−1.31, Q_c⁻¹ = 0.008*f^−0.84 and respectively. Compared to the other attenuation factors Q_c⁻¹ and are less dependent on the frequency.     

Gem-quality transparent diaspore (zultanite) in bauxite deposits of the İlbir Mountains, Menderes Massif, SW Turkey

Several m-thick, karst-unconformity-type metabauxite horizons in the İlbir Mountains of SW Turkey host open-space mineralization of gem-quality diaspore (trademarked as zultanite), associated with muscovite, hematite, ilmenite, chloritoid, and younger calcite. The hydrothermal-metamorphogenic mineralization occurs in fracture zones (veins and open structures) that crosscut the metabauxite horizons, but does not extend into the marble host rocks. The white to dark gray marble sequence (over 2,000 m in thickness) is of Cretaceous depositional age and was affected by Alpine (Paleogene) tectonometamorphism which caused the hydrothermal remobilization of primary bauxite components into crosscutting structures.     

Lithology Discrimination in Foreland Basin with Landsat TM

The Kahramanmaraş Foreland Basin (KFB) margins are formed by Paleozoic-Mesozoic limestone, metamorphic and ophiolite. This basin contains sandstone and claystone alternations with lesser amounts of reefal limestone, channelized conglomerates, debrites and slump deposits. An irregular topography and absence of path obscured the accurate and complete mapping of the basin. Thus, Landsat TM images were used. The RGB 751 false colour composites were chosen due to abundant claystone and limestone content of the KFB. The RGB PCA 145 was preferred due to high loading of TM bands 5 (clay and iron oxide mineral), 7 (carbonate mineral), 3 and 1 (albedo and topography). The RGB 5/7-5/1-4 (light green dots in 5/7 indicate enhanced claystone area and OH^- bearing alteration zone; red dots in 5/1 indicate enhanced iron oxide bearing alteration zone; fourth band for water bearing minerals) shows the transportation way of sediments. The OH^- and iron oxide bearing alteration zones are found on older source rocks and younger deposition area. Main lithological boundary, geometry and provenance properties of the KFB were satisfactorily obtained from the Landsat TM images. However, low spatial resolution (30 m) prevents detail facies discrimination that still requires hard field working and/or detailed satellite images.     

A particle mechanics approach for the dynamic strength model of the jointed rock mass considering the joint orientation

In nature, there exist several forms of anisotropy in rock masses due to the presence of bedding planes, joints, and weak layers. It is well understood that the anisotropic properties of jointed rock masses significantly affect the stability of surface and underground excavations. However, these critical anisotropic characteristics are often ignored in existing uniaxial dynamic failure criteria. This study investigates the effect of a pre-existing persistent joint on the rate-dependent mechanical behaviours of a rock mass using a particle mechanics approach, namely, bonded particle model (BPM), to realistically replicate the mechanical response of the rock mass. Firstly, in order to capture the rate-dependent response of the jointed rock mass, the BPM model is validated using published experimental data. Then, a dynamic strength model is proposed based on the Jaeger criterion and simulation results. To further investigate the dynamic behaviours, the dynamic uniaxial compressive strength (UCS) for anisotropic rock masses with various joint orientations is investigated by subjecting the BPM models to uniaxial compression numerical tests with various strain rate. The proposed dynamic strength model is validated based on numerical simulation results. Finally, the fragmentation characteristics of the jointed rock masses are analysed, which demonstrate that the failure mode affects the dynamic UCS. This is further confirmed by the analysis of the orientations of microscopic cracks generated by the compression loading.     

Spatial and temporal variation of suspended sediment concentration versus turbidity in the stream Harşit Watershed,NE Turkey

Suspended sediment related studies based on direct measurements for Turkish rivers and streams are very few for various reasons such as cost, time, or fewer operational sediment gauging stations, and thus the researchers tend to look for indirect methods. Turkey is a developing country and in need of many investments, which resulted in engineering and management modifications in its river and stream systems. This paper investigates the spatial and temporal variations of suspended sediment concentration (SSC, mg/L) versus turbidity (NTU) in the stream Har?it watershed having a length of the main branch at 143 km and catchment area of 3,280 km², Eastern Black Sea Basin of Turkey. Subsequently, the effect of the all kinds of anthropogenic activities was evaluated, namely, dam operation, levee construction, municipal wastewater discharge, sand–gravel mining on SSC, and turbidity in the watershed. In situ turbidity monitoring and water sampling studies were semimonthly conducted at ten stations from March 2009 to February 2010. On a semimonthly basis, it was revealed that SSC and turbidity values having significant correlation varied spatially and temporarily. The municipal wastewater discharge from the city of Gümü?hane together with the decreasing flow rate revealed itself with a significant increase in the turbidity and SSC, especially in the summer months. Torul Dam having a reservoir volume of 168 hm³ could trap 78.6 % of the SSC and could remove 66.6 % of the turbidity, thanks to its long hydraulic residence time; however, Kürtün Dam released the suspended sediment as a result of its sluiceway tunnel operation. Sand–gravel mining activities between the last two stations severely affected the water quality by increasing the SSC and turbidity.