Strain rotation coupling and its implications on the measurement of rotational ground motions

Spatial derivatives of the seismic wave field are known to be sensitive to various site effects (e.g., cavity effects, topography, and geological inhomogeneities). In this study, the focus is on strain rotation coupling that can cause significant differences between point measurements compared to array-derived rotational motions. The strain rotation coupling constants are estimated based on finite element simulations for inhomogeneous media as well as for the 3D topography around Wettzell, Germany (the location of the G ring laser). Using collocated array and ring laser data, the coupling constants of the ring laser itself are shown to be small. Several examples are shown to illustrate the order of magnitude that strain-induced rotation might have on the seismograms in the near field of volcanoes as well as in the far field and in the low-frequency spectrum (free oscillations).     

Toroidal free oscillations of the Earth observed by a ring laser system: a comparative study

In this study, we explore the potential of measuring systematically the Earth's free oscillations using ring laser gyro (RLG) vertical axis rotational records. The RLG that we use is the vertical axis G-ring laser system of the Geodetic Observatory Wettzell (Germany). In 2009, its signal-to-noise ratio was considerably improved over the broadband frequency range of seismic measurements. Since then, three large magnitude earthquakes have occurred (Samoa Islands 2009; Maule, Chile, 2010; and Tohoku, Japan, 2011), leading to the first direct observations of rotational ground motions induced by toroidal free oscillations of the Earth. We compare these G-ring laser observations with synthetic seismograms computed by summing normal modes. We also analyse amplitude spectra of real and synthetic data to aid in the interpretation of the observations. We show that several toroidal modes are detected by the G-ring laser for earthquakes with a moment magnitude M _W????8.0 and that our observations are in reasonable agreement with the synthetic spectra. We also report evidence for mode coupling in both translation and rotation spectra.     

Mineral potential mapping in Central Iran using fuzzy ordered weighted averaging method

The aim of this work is to introduce the application of the fuzzy ordered weighted averaging method as a straightforward knowledge‐driven approach to explore porphyry copper deposits in an airborne prospect. In this paper, the proposed method is applied to airborne geophysical (potassium radiometry, magnetometry, and frequency‐domain electromagnetic) data, geological layers (fault and host rock zones), and various extracted alteration layers from remote sensing images. The central Iranian volcanic–sedimentary belt in Kerman province of Iran that is located within the Urumieh–Dokhtar (Sahand–Bazman) magmatic arc is chosen for this study. This region has high potential of mineral occurrences, especially porphyry copper, containing some active world‐class copper mines such as Sarcheshmeh. Two evidential layers, including the downward continued map and the analytic signal of such filtered magnetic data, are generated to be used as geophysical plausible traces of porphyry copper occurrences. The low values of the resistivity layer acquired from airborne frequency‐domain electromagnetic data are also used as an electrical criterion in this study. Four remote sensing evidential layers, including argillic, phyllic, propylitic, and hydroxyl alterations, are extracted from Advanced Spaceborne Thermal Emission and Reflection Radiometer images in order to map the altered areas associated with porphyry copper deposits. The Enhanced Thematic Mapper plus images are used to map iron oxide layer. Since potassium alteration is the mainstay of copper alteration, the airborne potassium radiometry data are used. Here, the fuzzy ordered weighted averaging method uses a wide range of decision strategies in order to generate numerous mineral potential/prospectivity maps. The final mineral potential map based upon desired geo‐data set indicates adequately matching of high‐potential zones with previous working mines and copper deposits.     

Validation of Hyperbolic Model by the Results of Triaxial and Direct Shear Tests of Municipal Solid Waste

The increasing demand of engineering landfills requires that designers propose a framework for landfill design, construction, repair and maintenance. As municipal solid waste (MSW) is a major part of a landfill, the analysis should consider MSW mechanical behavior using a constitutive model. To investigate this, 18 direct shear (DS) and triaxial (TX) tests were conducted on MSW samples with different fiber contents. Different shearing mechanisms lead to understand effects of fibers on stress–strain response. Based on obtained results the hyperbolic model Duncan and Chang (J Soil Mech Found Div 96(5):1629–1653, 1970) has been employed to simulate the TX results indicating the ability of the model to predict stress–strain behavior of MSW. This model could also be employed to the DS test results with some assumptions. The model can capture DS stress–strain response well whereas for TX tests the predictions were just enough. The experimental results and two sets of proposed MSW parameters of hyperbolic model have been compared and discussed.     

Optimal location of additional exploratory drillholes using afuzzy-artificial bee colony algorithm

In most research studies, the problem of locating additional drillhole is simplified, and the ore body is considered as a 2d object. In this study, location of additional drillholes are optimized by considering the third dimension of the ore body, the azimuth and the dip of additional drill holes. A new objective function is defined to address the effect of rock type in locating new drillholes. The optimization problem is solved using a novel fuzzy-artificial bee colony algorithm, called FABC. The parameters of the FABC algorithm is dynamically adjusted using a designed fuzzy inference system with three performance measures as inputs and two outputs. The comparison performance with state-of-the-art optimization algorithm, using a nonparametric hypothesis test, indicates higher performance of the FABC algorithm. The results indicate significantly a decrease of kriging variance by introducing additional drillholes.     

Radiative surface temperature and convective flux calculation over crop canopies

The analysis presented in this paper aims at a better understanding of the potential role of radiative temperature, as measured by a radiometer over crops, in sensible heat flux calculation. Defining radiative temperature as the mean temperature of the surfaces viewed by the radiometer (leaves and soil surface) and assuming that an Ohm's law type formula can be used to express sensible heat flux as a function of the difference between air temperature and radiative temperature, the aerodynamic resistance which divides this temperature difference has been analytically defined. The parameters which appear in the resistance expression depend essentially on wind velocity and canopy structure but also on the inclination angle of the radiometer. Finally an experimental verification is presented with data obtained over a potato crop.     

Optimum design of single-frequency dynamic dampers

The problem of damping the vibration amplitude of machines and structures has considerable practical importance. This paper discusses the design of optimum vibration absorbers for linear damped systems operating at a certain excitation frequency. The problem is first formulated as a mathematical programming scheme. The systematic design discussed in this paper has significant advantages for those vibratory systems run primarily at a specific frequency.     

Petrographic and geochemical study of Jurassic dolostones from Lebanon: Evidence for superimposed diagenetic events

The Jurassic rock sequence in Lebanon is characterized by pervasive dolomitization (thickness > 1000 m). Two distinct dolostones are recognized within this rock succession: fine-to-medium crystalline seepage-reflux grey dolostone and coarse-crystalline hydrothermal beige dolostone. In this contribution, field, petrographic, and geochemical investigations on a dolostone ‘tongue’, occurring in Late Jurassic carbonates in central Lebanon, are discussed. The dolostone ‘tongue’ consists predominantly of the beige Late Jurassic hydrothermal dolostones. During and/or after the deposition of the overlying continental sandstones (Early Cretaceous), meteoric water percolated through the sand layers and into the underlying beige dolostones. This resulted first in dolomite intracrystalline dissolution, and then in the precipitation of oxides/hydroxides within the pore space. Finally, the precipitation of ferroan dolomite cement — from reduced fluids during a new stage of burial — took place. This study attempts to explain how superimposed diagenetic events result in a single pervasive dolostone body.     

Aftershock probabilistic seismic hazard analysis for Bushehr province in Iran using ETAS model

Natural Hazards - Aftershock probabilistic seismic hazard analysis (APSHA) has a key role in risk management after a major earthquake. The main goal of the current study is to assess aftershock...