Authors' reply to the discussion by Brendon A. Bradley of ‘A framework for the evaluation of ground motion selection and modification procedures’

In this short communication, we respond to the comments made by Dr Brendon A. Bradley and provide additional context to our paper under discussion.Copyright © 2015 John Wiley & Sons, Ltd.     

Evolution of the basalts from three back-arc basins of southwest Pacific

 Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau basins from the southwest Pacific, have been studied to understand their magmatic evolution. Basalt from the western Woodlark Basin (Dobu Seamount) indicates mixing of a near-primitive magma with fractionated basaltic melt in shallow magma chambers. Basalts from Manus Basin and Central Lau Spreading Center (Lau Basin) are typical N-MORBs, and they exhibit olivine fractionation under high oxidizing conditions while basalts from Mangatolu Triple Junction (Lau Basin) are enriched in Al₂O₃, K₂O, and Zr indicative of a contribution from a subducting plate. Received: 4 August 1998 / Revision received: 19 February 1999     

Critical response of structures to multicomponent earthquake excitation

This paper aims to develop an improved understanding of the critical response of structures to multicomponent seismic motion characterized by three uncorrelated components that are defined along its principal axes: two horizontal and the vertical component. An explicit formula, convenient for code applications, has been derived to calculate the critical value of structural response to the two principal horizontal components acting along any incident angle with respect to the structural axes, and the vertical component of ground motion. The critical response is defined as the largest value of response for all possible incident angles. The ratio r_cr/r_srss between the critical value of response and the SRSS response—corresponding to the principal components of ground acceleration applied along the structure axes—is shown to depend on three dimensionless parameters: the spectrum intensity ratio γ between the two principal components of horizontal ground motion characterized by design spectra A(T_n) and γA(T_n); the correlation coefficient α of responses r_x and r_y due to design spectrum A(T_n) applied in the x‐ and y‐directions, respectively; and β = r_y/r_x. It is demonstrated that the ratio r_cr/r_srss is bounded by 1 and . Thus the largest value of the ratio is , 1.26, 1.13 and 1.08 for γ = 0, 0.5, 0.75 and 0.85, respectively. This implies that the critical response never exceeds times the result of the SRSS analysis, and this ratio is about 1.13 for typical values of γ, say 0.75. The correlation coefficient α depends on the structural properties but is always bounded between −1 and 1. For a fixed value of γ, the ratio r_cr/r_srss is largest if β = 1 and α = ±1. The parametric variations presented for one‐storey buildings indicate that this condition can be satisfied by axial forces in columns of symmetric‐plan buildings or can be approximated by lateral displacements in resisting elements of unsymmetrical‐plan buildings. Copyright © 2000 John Wiley & Sons, Ltd.     

Palaeomagnetics and igneous activity of the area adjoining the south-westem margin of the Cuddapah basin, India

Summary. Fifty-six orientated samples were collected from 13 sites on five dolerite dykes (between lat.14°23°N, long.77°43'E and lat.14°08'N, long. 77°49'E), which adjoin the south-western margin of the Cuddapah basin in Anantapur district, Andhra Pradesh. After af demagnetization, two dykes (five sites) striking ENE possess similar magnetic directions, (1) D = 57°, 1=-69° (K = 52, α₉₅= 7°) and (2) D = 71°, I = -72° ( K = 260, α₉₅= 5°). Again dykes (3) (three sites), and (4) (two sites) have similar strike (NE) and magnetic directions, D = 64°. I=-7 α( K = 142, α₉₅ = 8°) and D = 53°, I =-8° (K = 142, α₉₅= 6°) and dyke (5) (two sites) striking NW shows D = 320°, I = -34° ( K = 68, α₉₅= 13°). Remanent directions estimated from total field magnetic anomaly data agree well with these results. Synthesis of these data with 10 other published palaeomagnetic studies of Precambrian dolerite dykes on the Indian peninsula, suggest that these three systems of dykes adjoining the Cuddapah basin had been emplaced prior to the basin formation perhaps representing the initial thermal event responsible for the basin development and also that there have been at least three separate periods of dyke emplacement on this shield. The radiometric data, however, are very sparse and these periods cannot be dated with confidence.     

Comparison of Fusion Techniques for Very High Resolution Data for Extraction of Urban Land-Cover

This paper aims in presenting a thorough comparison of performance of pan sharpening techniques, belonging to spatial, spectral, scale-space and spatial-frequency domain, for Very High Resolution Satellite Data. With the availability of new Very High Resolution sensors, especially, World View-2 sensor, which provides data at sub-meter level, the need for fusion of Panchromatic (PAN) and Multispectral (MS) images has to be further investigated. Pan-sharpening techniques namely, Hue-Saturation-Intensity, Brovey Transform, Principal Components Analysis, Discrete Wavelet Transform, Stationary Wavelet Transform, Non Sub-sampled contourlet Transform and Pseudo Wigner Distribution (PWD) fusion method have been selected for the fusion of PAN and MS images of World View-2 sensor. Further, the comparison of performance of each of the techniques have been carried out by using various evaluation indicators, such as, Root Mean Square Error, Peak Signal-to-Noise Ratio, Correlation Coefficient, Universal Image Quality Index. It is found that PWD based fusion technique gives good result with a good trade-off between the preservation of spectral information and enhancement of spatial resolution.     

Evaluation of TMPA 3B42 Precipitation Estimates during the Passage of Tropical Cyclones over New Caledonia

A deficit in precipitation may impact greatly on soil moisture, snowpack, streamflow, groundwater and reservoir storage. Among the several approaches available to investigate this phenomenon, one of the most applied is the analysis of dry spells. In this study, a non-homogeneous Poisson model has been applied to a set of high-quality daily rainfall series, recorded in southern Italy (Calabria region) during the period 1981–2010, for the stochastic analysis of dry spells. Firstly, some statistical details of the Poisson models were presented. Then, the proposed model has been applied to the analysis of long dry spells. In particular, a Monte Carlo technique was performed to reproduce the characteristics of the process. As a result, the main characteristics of the long dry spells have shown patterns clearly related to some geographical features of the study area, such as elevation and latitude. The results obtained from the stochastic modelling of the long dry spells proved that the proposed model is useful for the probability evaluation of drought, thus improving environmental planning and management.     

Evaluation of relief aspects morphometric parameters derived from different sources of DEMs and its effects over time of concentration of runoff (T<Subscript>C</Subscript>)

An attempt has been made to study the relief aspects from three different sources of Digital Elevation Models (DEMs) viz., Survey of India (SOI) topographic map (1:25,000), Shuttle Radar Topography Mission (SRTM-90 m and SRTM-30 m) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER-30 m). These aspects are evaluated to examine differences among them and their influence on time of concentration (T_C) of runoff at Moolbari Experimental Watershed (MEW), Sub Himalayan region (Shimla, District of Himachal Pradesh) India. For detailed study of relief aspects, morphometry parameters, SOI topographic map (as base map) were used. The results show that the relief aspects morphometric parameters derived from the SRTM_30m and ASTER_30m lie between SOI topographic map, and SRTM_90m. We estimated T_C of 21 micro watersheds from different sources DEMs by using Kirpich, Johnstone, Témez, and Barnsby equation only. Témez and Barnsby equation demonstrate high potential for the identification of T_C from SOI Topographic map, SRTM_90m, ASTER and SRTM_30m DEMs. T_{C_Topo} has a positive relationship with T_C__SRTM90m, T_C__ASTER and T_C__SRTM30m for both Témez, and Barnsby equation with R²=0.804_{Topo & SRTM90m}, 0.810_{Topo & ASTER} & 0.839_{Topo & SRTM30m} and 0.712_{Topo & SRTM90m}, 0.747 _{Topo & ASTER} & 0.785 _{Topo & SRTM30m}. Further statistical test of Témez, and Barnsby equation based T_C, only Témez equation based T_C qualify/satisfy the statistical test. by considering all freeware DEMs a Semi-empirical model (SEM) has been developed, where T_C predicted in term of T_C__Topo is a function of T_{C_SRTM90m}, T_{C_ASTER} and T_{C_SRTM30m}. This SEM has R²=0.883 and adjusted R= 0.874, Multiple R=0.907 and with Standard Error =2.131 at 95% confidence level. Comparison of the T_C derived from the multiple regressions among three DEMs with T_C__Topo shows an RMSE of 3.803, R-RMSE of 0.169, NRMSE of 0.342, R² of 0.89, and RMSE% of 3.296 for Témez equation.     

Evaluation of the boundary layer depth in semi-arid region of India

The annual variation in Planetary Boundary Layer (PBL) height is determined from the profiles of conserved thermodynamic variables, i.e. virtual potential temperature θ_v, equivalent potential temperature θ_e and saturated equivalent potential temperature θ_es, using radiosonde data at Anand (23°35′N, 72°55′E, 45.1 m a.s.l.), India. Out of all the variables, the θ_v profile seems to provide the most reasonable estimate of the PBL height. This has been supplemented by T–Phi gram analysis for specific days. The analysis has been done for 00, 03, 06, 09 and 12 GMT for the 14th and 15th day of each month in the year 1997 based on LASPEX-97 data. In winters the height of boundary layer is very low due to subsidence and radiation cooling while heights in pre-monsoon months exhibit large variations.