The temporal variation of teleseismic P-residuals for stations in southern California

Teleseismic P residuals have been monitored as a function of time at 13 stations in southern California during the 5-year period 1972 to 1976. These residuals, when normalized to minimize common path and source effects, and corrected for the marked azimuthal dependence of residuals in southern California, show no significant variation. This indicates that no detectable velocity changes have occurred during this time in the vicinity of the stations monitored. It is estimated that a velocity change of ∼9 per cent occurring over a path length of 10 km and lasting for at least 6 months should be resolvable. Either such changes have not taken place in the region monitored, or any velocity anomalies are confined to a small depth range in the crust, and are poorly sampled by teleseismic waves

Post-shock temperatures in minerals

An experimental technique has been developed for the measurement of post-shock temperatures in a wide variety of materials, including those of geophysical interest such as silicates. The technique uses an infrared radiation detector to determine the brightness temperature of samples shocked to pressures in the range 5 to ∼ 30 GPa; in these experiments measurements have been made in two wavelength ranges (4.5 to 5.75 μm; 7 to 14 μm). Reproducible results, with the temperatures in the two wavelength bands generally in excellent agreement, have been obtained for aluminium-2024 (10.5 to 33 GPa; 125 to 260°C), stainless steel-304 (11.5 to 50 GPa; 80 to 350°C), crystalline quartz (5.0 to 21.5 GPa; 80 to 250°C), forsterite (7.5 to 28.0 GPa; ∼ 30 to 160°C) and Bamble bronzite (6.0 to 26.0 GPa; ∼ 30 to 225°C). These results are generally much higher at low pressures (where they may even be in excess of the calculated shock temperatures) than the values calculated assuming a hydrodynamic rheology and isentropic release parallel to the Hugoniot but tend towards them at higher pressures. In aluminium-2024, the theoretical post-shock temperatures, assuming a fluid-like rheology, are 35 to 218°C, for the pressure range 10.5 to 33 GPa. However, the results are in considerably better agreement with values calculated assuming elasto-plastic behaviour (80 to 270°C) which probably also causes the high measured temperatures for stainless steel. In forsterite the measured values ranged from 65°C at 9.6 GPa (there was no detectable rise at 7.5 GPa) to 156° at 28.0 GPa, whereas the ‘hydrodynamic values’ were 30 to 120°C. Values obtained for quartz were in excellent agreement with those calculated by Mashimo et al. using release adiabat data. It is concluded that release adiabat data should be used, wherever available, for calculations of residual temperature, and that adequate descriptions of the shock and release processes in minerals need to be more complex than generally assumed

The azimuthal variation of teleseismic P-residuals in southern California: Implications for upper-mantle structure

The azimuthal variation of teleseismic P-delays has been investigated for stations of the USGS-Caltech Southern California Seismographic Network. Normalized residuals show azimuthal variations as large as 1.2 s, and must be explained in terms of upper mantle structure. The observed azimuthal dependence implies the presence of a region of depressed velocity beneath the Imperial Valley, and regions of increased velocity below the Sierra Nevada, southwest Arizona, and much of the Transverse Ranges. The last is a major high velocity ridge-like structure, extending from a depth of ~40 km to over 100 km, which crosses, but is not offset by, the San Andreas Fault. This suggests that the plate boundary at depth may diverge from its surface expression. The horizontal shear resulting from the divergence of crust and mantle plate boundaries may be accommodated by a zone of decoupling associated with the regionally observed 7.8 km/s (P_n) layer

The azimuthal variation of teleseismic P-residuals in southern California: Implications for upper-mantle structure

The azimuthal variation of teleseismic P-delays has been investigated for stations of the USGS-Caltech Southern California Seismographic Network. Normalized residuals show azimuthal variations as large as 1.2 s, and must be explained in terms of upper mantle structure. The observed azimuthal dependence implies the presence of a region of depressed velocity beneath the Imperial Valley, and regions of increased velocity below the Sierra Nevada, southwest Arizona, and much of the Transverse Ranges. The last is a major high velocity ridge-like structure, extending from a depth of ~40 km to over 100 km, which crosses, but is not offset by, the San Andreas Fault. This suggests that the plate boundary at depth may diverge from its surface expression. The horizontal shear resulting from the divergence of crust and mantle plate boundaries may be accommodated by a zone of decoupling associated with the regionally observed 7.8 km/s (P_n) layer

The creation of the Global Scales for Early Development (GSED) for children aged 0–3 years: combining subject matter expert judgements with big data

Introduction With the ratification of the Sustainable Development Goals, there is an increased emphasis on early childhood development (ECD) and well-being. The WHO led Global Scales for Early Development (GSED) project aims to provide population and programmatic level measures of ECD for 0–3 years that are valid, reliable and have psychometrically stable performance across geographical, cultural and language contexts. This paper reports on the creation of two measures: (1) the GSED Short Form (GSED-SF)—a caregiver reported measure for population-evaluation—self-administered with no training required and (2) the GSED Long Form (GSED-LF)—a directly administered/observed measure for programmatic evaluation—administered by a trained professional.Methods We selected 807 psychometrically best-performing items using a Rasch measurement model from an ECD measurement databank which comprised 66 075 children assessed on 2211 items from 18 ECD measures in 32 countries. From 766 of these items, in-depth subject matter expert judgements were gathered to inform final item selection. Specifically collected were data on (1) conceptual matches between pairs of items originating from different measures, (2) developmental domain(s) measured by each item and (3) perceptions of feasibility of administration of each item in diverse contexts. Prototypes were finalised through a combination of psychometric performance evaluation and expert consensus to optimally identify items.Results We created the GSED-SF (139 items) and GSED-LF (157 items) for tablet-based and paper-based assessments, with an optimal set of items that fit the Rasch model, met subject matter expert criteria, avoided conceptual overlap, covered multiple domains of child development and were feasible to implement across diverse settings.Conclusions State-of-the-art quantitative and qualitative procedures were used to select of theoretically relevant and globally feasible items representing child development for children aged 0–3 years. GSED-SF and GSED-LF will be piloted and validated in children across diverse cultural, demographic, social and language contexts for global use

The creation of the Global Scales for Early Development (GSED) for children aged 0-3 years: Combining subject matter expert judgements with big data

Introduction With the ratification of the Sustainable Development Goals, there is an increased emphasis on early childhood development (ECD) and well-being. The WHO led Global Scales for Early Development (GSED) project aims to provide population and programmatic level measures of ECD for 0-3 years that are valid, reliable and have psychometrically stable performance across geographical, cultural and language contexts. This paper reports on the creation of two measures: (1) the GSED Short Form (GSED-SF) - a caregiver reported measure for population-evaluation - self-administered with no training required and (2) the GSED Long Form (GSED-LF) - a directly administered/observed measure for programmatic evaluation - administered by a trained professional. Methods We selected 807 psychometrically best-performing items using a Rasch measurement model from an ECD measurement databank which comprised 66 075 children assessed on 2211 items from 18 ECD measures in 32 countries. From 766 of these items, in-depth subject matter expert judgements were gathered to inform final item selection. Specifically collected were data on (1) conceptual matches between pairs of items originating from different measures, (2) developmental domain(s) measured by each item and (3) perceptions of feasibility of administration of each item in diverse contexts. Prototypes were finalised through a combination of psychometric performance evaluation and expert consensus to optimally identify items. Results We created the GSED-SF (139 items) and GSED-LF (157 items) for tablet-based and paper-based assessments, with an optimal set of items that fit the Rasch model, met subject matter expert criteria, avoided conceptual overlap, covered multiple domains of child development and were feasible to implement across diverse settings. Conclusions State-of-the-art quantitative and qualitative procedures were used to select of theoretically relevant and globally feasible items representing child development for children aged 0-3 years. GSED-SF and GSED-LF will be piloted and validated in children across diverse cultural, demographic, social and language contexts for global use