Macroseismic estimates of magnitude in Italy

A multi-parametric study of empirical relationships between macroseismic data and magnitude is presented for the Italian region by the analysis of a new extended data set concerning 146 earthquakes. The available magnitude determinations include all of the most intense earthquakes which occurred in Italy in the last century and have been obtained by an accurate revision of original instrumental data. Intensity data have been revised and upgraded on the basis of the most recent studies: only local intensities directly documented have been used. Macroseismic determinations ofM _s ,m _B andM _wa magnitudes have been performed. The empirical relationships between maximum felt intensity (I _max ) and magnitude have been determined by the use of a distribution-free approach and a linear regression analysis. This last parameterization allows for the explanation of more than 60% of the variation in magnitude. In order to improve these results, the linear dependence between magnitude,I _max and average distances (in logarithm) corresponding to fixed attenuation values has been explored. The comparison between instrumental magnitudes and corresponding macroseismic estimates obtained from empirical relationships shows that the respective uncertainties are comparable.     

Converting Radial Distortions Due to Geopotential Models to Geopotential Stokes Coefficients

A methodology for improving geopotential models has been developed. Theoretical relations have been derived converting coefficients in harmonic expansions for radial distortions due to geopotential models into geopotential Stokes coefficients. Terms of the order of 10 ^–10 in magnitude have been retained.     

Variations in the schumann resonance polarization ellipse in the horizontal and vertical planes according to observations at the Barentsburg and Lovozero observatories

The diurnal variations in the amplitude and parameters of polarization ellipses of the first Schumann resonance according to three magnetic field components, observed on December 1–10, 2007, at the Barentsburg and Lovozero observatories, have been studied. Ellipses have been constructed in the (H, D) and (H, Z) planes. The value of the minor axis, inclination of the major axis, ellipticity, and the rotation direction have been estimated. The vertical magnetic component of the Schumann resonance is three to four times as small as the horizontal component. The difference in the diurnal variations in the ellipse parameters between both observatories has been found. The effect can be caused by a difference in the Earth’s conductivity in the vicinity of the observatories and by conductivity anisotropy. The major axis inclination and ellipticity have semidiurnal components. The polarization vector mostly rotates from D to H in the horizontal plane and from Z to H in the vertical plane at both stations.     

The use of the exponent K(q) function to delimit homogeneous regions in regional frequency analysis of extreme annual daily rainfall

The regional frequency analysis of extreme annual rainfall data is a useful methodology in hydrology to obtain certain quantile values when no long data series are available. The most crucial step in the analysis is the grouping of sites into homogeneous regions. This work presents a new grouping criterion based on some multifractal properties of rainfall data. For this purpose, a regional frequency analysis of extreme annual rainfall data from the Maule Region (Chile) has been performed. Daily rainfall data series of 53 available stations have been studied, and their empirical moments scaling exponent functions K(q) have been obtained. Two characteristics parameters of the K(q) functions (γ_max and K(0)) have been used to group the stations into three homogeneous regions. Only five sites have not been possible to include into any homogenous regions, being the local frequency analysis of extreme daily rainfall the most appropriate method to be used at these locations. Copyright © 2014 John Wiley & Sons, Ltd.     

Seismic Ground Motion in Napoli for the 1980 Irpinia Earthquake

— The seismic ground motion in the urban area of Napoli has been computed for the 1980 earthquake (M_s = 6.9) with a hybrid technique based on the mode summation and the finite difference methods. The detailed geological setting of each quarter has been reconstructed from several stratigraphies and six geological zones have been recognized. Shear-wave velocity profiles have been assigned, based on hole tests and inversion of Rayleigh group velocities artificially generated. Realistic SH and P-SV wave seismograms have been computed along the representative cross sections of each zone, by assuming selected velocity profiles. Spectral amplifications of 2–4 have been computed at frequencies roughly corresponding to the eigenfrequencies of the most damaged buildings. Moreover, following the intensity-PGA correlations found for the Italian territory, the predicted peak ground accelerations, 0.04–0.10 g correspond to the intensity range VII-VIII on the MCS scale, in agreement with the observed data.     

Plasma pressure distribution in the equatorial plane of the Earth’s magnetosphere at geocentric distances of 6–10<Emphasis Type="Italic">R</Emphasis><Subscript><Emphasis Type="Italic">E</Emphasis></Subscript> according to the international THEMIS mission data

The structure of the averaged plasma pressure distribution in the plasma ring around the Earth at geocentric distances of ∼6–10R _E has been determined. The distribution function moments measured on the international THEMIS mission satellites have been used. The plasma pressure distribution in the equatorial plane at 15R _E > X_SM > −15R _E and 15R _E > Y_SM > −15R _E has been statistically studied. The radial dependence of the plasma pressure at the day-night and morning-evening meridians has been analyzed. It has been indicated that the plasma ring around the Earth has a structure, which is close to being azimuthally symmetric. The achieved results have been compared with the pressure distributions obtained previously. It has been indicated that in the overlapping regions, the achieved results agree with the previously obtained data within the pressure determination errors.     

Crustal structure of the Peninsular India

Summary Earthquake parameters for the forty aftershocks of the main Koyna earthquake of 10 December, 1967, have been determined. Depths of the foci of the earthquakes have been found to vary between 2 to 17 km. The velocities for the phasesP _g ,P ^*,P _n have been observed to be 5.78±0.00, 6.58±0.04, 8.19±0.02 km/sec, and forS _g ,S ^*,S _n to be 3.42±0.00, 3.92±0.01 and 4.62±0.01 km/sec respectively. A two-layered crustal model has been interpreted for the Peninsular shield with the average thickness of the granitic layer as 20 km and that for the basaltic layer as 18.7 km. A plot of the epicenters suggests a NNE to SSW orientation of the fault.     

SEISMIC REFRACTION METHOD TO STUDY THE FOUNDATION ROCK OF A DAM*

Dynamic elastic moduli like E, μ, K and μ of the foundation rock of a dam have been determined by finding V_p- and V_s-velocities by seismic refraction with a hammer as source. Some parameters such as “fracture frequency” and “rock quality designation” (RQD) of the foundation rock have been derived using “average regression curves” and V_p-velocities. By comparing K/μ with V_p/V_s, a few locations showing weathered conditions have been demarcated. This compares well with RQD values of those locations.     

Model calculations of the total electron content for the system of GPS satellites

The numerical global self-consistent model of the Earth’s thermosphere, ionosphere and protonosphere (GSM TIP), which makes it possible to calculate all the main parameters of the near-Earth plasma, is used to calculate the total electron content (TEC). Calculations have been performed along the radiosignal propagation trajectory between a surface receiving point and a GPS satellite. The TEC value calculated from the satellite data have been compared with such a “true model” TEC value for magnetically quiet conditions of the spring equinox and moderate solar activity. The relative errors in determining the satellite data-based TEC for two European (Troms have been calculated. It has been indicated that an increase in the number of satellites not always results in an increase in accuracy of the TEC value measured on satellites.     

Reflection and refraction of waves at the interface of an isotropic medium over a highly anisotropic medium

In this paper, we have considered the reflection and refraction of a plane wave at an interface between two half-spaces. The lower half-spaces is composed of highly anisotropic triclinic crystalline material and the upper half-space is homogeneous and isotropic. It has been assumed that due to incidence of a plane quasi-P (qP) wave, three types of waves, namely, quasi-P (qP), quasi-SV (qSV) and quasi-SH (qSH), will be generated in the lower half space whereas P and S waves will be generated in the upper half space. The phase velocities of all the quasi waves have been calculated. It has been assumed that the direction of particle motion is neither parallel nor perpendicular to the direction of propagation. Some specific relations have been established between directions of motion and propagation, respectively. The expressions for reflection coefficients of qP, qSV, qSH and refracted coefficients of P and SV waves are obtained. Results of reflection and refraction coefficients are presented.     

Statistical distributions of water content and sizes for clouds above Europe

The statistics of quantities involved in the synthesis of cloud scenes have been investigated from an original data base. Frequency distributions of ice and water content (IWC), horizontal and vertical sizes (L and H), and top temperatures (T) of clouds above Europe have been derived for nine types of clouds (As, Cb, Ci, Cg, LwCg, OrCg, Cs, Ns, Sc). It appears that the cumulated frequency plots can be well fitted with log-normal or Weibull profiles, and that for IWC and T cloud types can be split into two or three classes according to slopes in logarithmic coordinates. Cross-correlation coefficients between IWC, L, H and T have been also derived. Implications for the physics of the cloud build-up processes are briefly outlined. Critical analysis and comparison of other published results are proposed.     

Estimation of Coda Wave Attenuation for the National Capital Region, Delhi, India Using Local Earthquakes

Attenuation of seismic waves is very essential for the study of earthquake source parameters and also for ground-motion simulations, and this is important for the seismic hazard estimation of a region. The digital data acquired by 16 short-period seismic stations of the Delhi Telemetric Network for 55 earthquakes of magnitude 1.5 to 4.2, which occurred within an epicentral distance of 100 km in an area around Delhi, have been used to estimate the coda attenuation Q_c. Using the Single Backscattering Model, the seismograms have been analyzed at 10 central frequencies. The frequency dependence average attenuation relationship Q_c = 142f ^1.04 has been attained. Four Lapse-Time windows from 20 to 50 seconds duration with a difference of 10 seconds have been analyzed to study the lapse time dependence of Q_c. The Q_c values show that frequency dependence (exponent n) remains similar at all the lapse time window lengths. While the change in Q₀ values is significant, change in Q₀ with larger lapsetime reflects the rate of homogeneity at the depth. The variation of Q_c indicates a definitive trend from west to east in accordance with the geology of the region.     

Causes of <Emphasis Type="Italic">NmF</Emphasis>2 longitudinal variations at mid- and subauroral latitudes under summer nighttime conditions

The main factors controlling NmF2 longitudinal variations at mid- and subauroral latitudes have been studied. The data of the Intercosmos-19 topside sounding, obtained at high solar activity for summer nighttime conditions, have been used in the analysis. The contributions of the solar ionization, neutral wind, and temperature and composition of the thermosphere to NmF2 longitudinal variations have been estimated based on ionospheric models. It has been indicated that NmF2 variations in the unsunlit midlatitude ionosphere mainly depends on the residual electron density and its decay under the action of recombination. At subauroral latitudes under summer nighttime conditions, the ionosphere is partially sunlit, and ionization by solar radiation mainly contributes to NmF2 longitudinal variations, whereas the effect of the neutral wind is slightly less significant. These results also indicate how the contribution of different factors to NmF2 longitudinal variations changes at different latitudes.     

Source mechanism and rupture propagation in the Mudurnu Valley,Turkey, earthquake of July 22, 1967

Summary First motions ofP waves and amplitude spectra ofG ₂ andG ₃ waves have been used to determine the source mechanism and rupture propagation. The amplitudes ofG ₃ waves have been corrected for the attenuation using aQ-model obtained from the amplitude spectra ofG ₂ andG ₃ waves. Observed directivities for the strike-direction agreed with a model of a bilateral fault propagated primarily from east to west.     

Refinement of predictive reaeration equations for a typical Indian river

Dissolved oxygen mass balance has been computed for different reaches of River Kali in western Uttar Pradesh (India) to obtain the reaeration coefficient (K₂). A total of 270 field data sets have been collected during the period from March 1999 to February 2000. Eleven most popular predictive equations, used for reaeration prediction and utilizing mean stream velocity, bed slope, flow depth, friction velocity and Froude number, have been tested for their applicability in the River Kali using data generated during field survey. The K₂ values computed from these predictive equations have been compared with the K₂ values observed from dissolved oxygen balance measurements in the field. The performance of predictive equations have been evaluated using error estimation, namely standard error (SE), normal mean error (NME), mean multiplicative error (MME) and correlation statistics. The equations developed by Smoot and by Cadwallader and McDonnell showed comparatively better results. Moreover, a refined predictive equation has been developed using a least‐squares algorithm for the River Kali that minimizes error estimates and improves correlation between observed and computed reaeration coefficients. Copyright © 2001 John Wiley & Sons, Ltd.     

Selecting the best IDF model by using the multifractal approach

In this work, the multifractal properties of hourly rainfall data recorded at a location in Southern Spain have been related to the scale properties of the corresponding intensity–duration–frequency (IDF) curves. Four parametric models for the IDF curves have been fitted to the quantiles of rainfall obtained using the generalized Pareto frequency distribution function with the extreme data series obtained for the same place. The scaling of the rainfall intensity moments has been analysed, and the empirical moments scaling exponent function has been obtained. The corresponding values of q₁ and γ₁ have been empirical and theoretically calculated and compared with some characteristics of the different IDF models. Thus, the scaling behaviour of IDF curves has been analysed, and the best model has been selected. Copyright © 2012 John Wiley & Sons, Ltd.     

On coda waves of earthquakes

Summary Coda waves viz. the tail portion of an earthquake record have been observed and analysed byCarder, Macelwane and others. They showed that the periods of such waves increase with the increase of epicentral distances.Carder observed that these waves have very little transverse component so that these may be considered as of the type of Rayleigh waves. RecentlyOmote showed that the Coda waves contain three periodsT ₁,T ₂,T ₃ of whichT ₁ increases with epi-central distances as observed by previous observers. ButT ₂,T ₃ remain constant for all earthquakes from different epicentral distances.Omote tried to explain this phenomenon by considering that the surface of the earth consists of several layers andT ₂,T ₃ are free oscillation periods of the surface layers.T ₁ period has been explained bySezawa and also byJeffreys which has been shown byGutenberg. The author has attempted to explain the periodsT ₂,T ₃ by considering passage of cracks at the focal region. The Rayleigh wave character of Coda waves and low velocity of such waves have been explained.     

Effects of micro- and nanoplastics on the physiology and metabolism of Portunus trituberculatus

Portunus trituberculatus is important in coastal benthic communities and a favorite seafood for coastal residents. However, microplastics have been detected in different tissues of P. trituberculatus, but the toxicological effects of micro- and nanoplastics (MNPs) on the different tissues of P. trituberculatus have not been reported. We found that the lethal effect of MNPs on P. trituberculatus is not obvious, but they can stimulate the body's stress response. The responses of P. trituberculatus tissues to MNPs are different, which may be due to differences in enzyme reactions between tissues and organs. Compared with microplastics (MPs), nanoplastics (NPs) have a more significant physiological and metabolic stress effect on P. trituberculatus because of their smaller particle size. In summary, plastic particles have physiological stress effects on the physiological metabolism of P. trituberculatus, which may be closely related to the plastic's particle size and concentration.     

Estimating permeability from field measurements of seismic attenuation in fractured chalk

Broadband (100–4000 Hz) cross‐hole seismic data have been acquired at a borehole test site where extensive hydrological investigations have previously been performed, including in situ estimates of permeability. The rock type is homogeneous chalk and fractures and bedding planes have been identified from well logs. High values of seismic attenuation, Q= 22 ≤ 27 ≤ 33, were observed over a 10 m depth interval where fracture permeability values of 20–50 darcy had been recorded. An attempt has been made to separate the attenuation due to scattering and intrinsic mechanisms. The estimated values of intrinsic attenuation, Q= 31 ≤ 43 ≤ 71, have been reproduced using a number of current theories of seismic‐wave propagation and fluid‐flow‐induced seismic attenuation in cracked and fractured media. A model that considers wavelength‐scale pressure gradients is the preferred attenuation mechanism. Model parameters were obtained from the hydro‐geological and seismic data. However, we conclude that it is not possible to use seismic Q to measure rock permeability remotely, principally because of the inherent uncertainties arising from model parameterisations.     

Evaluation of Hydraulic Conductivity Estimates from Various Approaches with Groundwater Flow Models

Significant efforts have been expended for improved characterization of hydraulic conductivity (K) and specific storage (S_s) to better understand groundwater flow and contaminant transport processes. Conventional methods including grain size analyses (GSA), permeameter, slug, and pumping tests have been utilized extensively, while Direct Push-based Hydraulic Profiling Tool (HPT) surveys have been developed to obtain high-resolution K estimates. Moreover, inverse modeling approaches based on geology-based zonations, and highly parameterized Hydraulic Tomography (HT) have also been advanced to map spatial variations of K and S_s between and beyond boreholes. While different methods are available, it is unclear which one yields K estimates that are most useful for high resolution predictions of groundwater flow. Therefore, the main objective of this study is to evaluate various K estimates at a highly heterogeneous field site obtained with three categories of characterization techniques including: (1) conventional methods (GSA, permeameter, and slug tests); (2) HPT surveys; and (3) inverse modeling based on geology-based zonations and highly parameterized approaches. The performance of each approach is first qualitatively analyzed by comparing K estimates to site geology. Then, steady-state and transient groundwater flow models are employed to quantitatively assess various K estimates by simulating pumping tests not used for parameter estimation. Results reveal that inverse modeling approaches yield the best drawdown predictions under both steady and transient conditions. In contrast, conventional methods and HPT surveys yield biased predictions. Based on our research, it appears that inverse modeling and data fusion are necessary steps in predicting accurate groundwater flow behavior.