High density neighborhoods: Who enjoys them?

To date, research into the subjective aspects of high density has focused mainly on the negative consequences of overcrowding. This study, in contrast, outlines some of the positive aspects of high density in neighborhoods, exploring the physical–spatial environment of two neighborhoods in the city of Haifa, Israel. It was found that while the relatively high residential density was similar in both neighborhoods (40 housing units per acre), this was more positively evaluated in one neighborhood as compared to the other. This can be attributed to some specific environmental and planning features. In particular, where physical planning enabled the potential advantages of high density to be realized, this was positively perceived and evaluated by local residents. Such advantages mainly comprised accessibility to a variety of services, more frequent public transportation, and access to open spaces within walking distance. Particularly advantageous were the increased opportunities for social gathering. At the same time, however, high density did not foster social relationships on the neighborhood level. The study further identified the gender and age groups that benefited most from the high density. Thus, women evaluated high density more positively than men. Young families with children and senior citizens (over 65) were also more likely to benefit, and to evaluate the high density environment more positively than other social groups.     

A detailed analysis of two seismic sequences in Abruzzo, Central Apennines, Italy

A three-component digital seismic network has been installed along central Apennines since the end of 1991. Two seismic sequences having main shocks of magnitudes 3.9 and 3.7 were recorded in August 1992 and June 1994, respectively. A detailed analysis of these sequences, including multiplet relocation, fault-plane solutions and source parameter estimation, is performed in the present paper. A correlation analysis allowed us to recognize a number of correlated events in the two sequences which were used for relative locations using a master event technique. This analysis allowed to obtain a better alignment of epicentral data along two almost orthogonal directions, following an Apenninic and an anti-Apenninic trend. For the two sequences, fault-plane solutions were evaluated by using a first arrival technique, resulting in mechanisms with predominant normal faulting for the 1992 and 1994 swarms. S-wave polarization analysis allowed to check the stability of the previous solutions and to reduce their range of uncertainty. The same technique was also applied to derive the composite fault-plane solutions from the aftershocks, resulting in solutions which are in good agreement with those derived from the main shocks of both sequences. Source parameters were then derived from the three-component records of 28 well-recorded events with seismic moment in the range 8.5 × 10¹⁰–1.0 × 10¹⁴ Nm. Stress drops ranged in the interval 0.3–52.3 bar and source radii were of the order of 100 m. Their scaling relations are in good agreement with other results derived from the analysis of other Italian earthquakes that occurred in regions of predominantly normal faulting tectonics (Apennines and Calabrian arc).     

From rags to riches? Migration and intergenerational change in London's housing market, 1971–91

Summary In 1971 under half of London's young people, then living with their parents, lived in households that owned their homes, while well over half lived in rented housing. By 1991, now no longer living with their parents, less than a quarter of these young people were tenants. This paper identifies the components of that intergenerational tenure mobility, distinguishing between home ownership in more, and less, 'desirable' wards, and quantifies the role of migration in mediating the overall changes in Londoner's housing market status between 1971 and 1991. It analyses the moderating factors contributing to housing status mobility, such as labour market mobility and household type, and assesses the differential impact of these processes on men and women. ONS Longitudinal Study data for the period 1971–91 are analysed. Findings are that the aggregate changes concealed a range of housing careers. In particular, in-migrants fared less well in the London housing market than in its labour market.     

The impact of changing subcanopy radiation on snowmelt in a disturbed coniferous forest

Understanding the role of forests on snowmelt processes enables better estimates of snow storages at a catchment scale and contributes to a higher accuracy of spring flood forecasting. A coniferous forest modifies the snowpack energy balance by reducing the total amount of solar shortwave radiation (SWR) and enhancing the role of longwave radiation (LWR) emitted by trees. This study focuses on changes in SWR and LWR at three sites with different canopy structure (Bohemian Forest, Czechia), including one site affected by the bark beetle (Ips typographus). Measurements of incoming and outgoing SWR and LWR were performed at all sites equipped with CNR4 Net Radiometers for three cold seasons. In addition to SWR and LWR, sensible and latent heat, and ground heat and energy supplied by liquid precipitation were calculated. The results showed that net SWR at the healthy forest site represented only 7% of the amount at the open site due to the shading effect of trees. In contrast, net LWR represented a positive component of the snowpack energy balance at the healthy forest site and thus contributed the most to snowmelt. However, the modelled snowmelt rates were significantly lower in the forest than in the open area since the higher LWR in the forest did not compensated for the lower SWR. The progressive decay of disturbed forest caused the decrease in mean net LWR from −3.1 W/m² to −12.9 W/m² and the increase in mean net SWR from 31.6 W/m² to 96.2 W/m² during the study period. These changes caused an increase in modelled snowmelt rates by 50% in the disturbed forest, compared to the healthy forest site, during the study period. Our findings have important implications for runoff from areas affected by land cover changes due to either human activity or climate change.     

Overview of the Italian strong motion database ITACA 1.0

The Italian Strong Motion Database, ITACA, was developed within projects S6 and S4, funded in the framework of the agreements between the Italian Department of Civil Protection (Dipartimento della Protezione Civile, DPC) and the Istituto Nazionale di Geofisica e Vulcanologia (INGV), starting from 2005. The alpha version of the database was released in 2007 and subsequently upgraded to version 1.0 after: (i) including the most recent strong motion data (from 2005 to 2007) recorded in Italy, in addition to the 2008 Parma earthquake, M 5.4, and the M ≥  4.0, 2009 Abruzzo seismic events; (ii) processing the raw strong motion data using an updated procedure; (iii) increasing the number of stations with a measured shear wave velocity profile; (iv) improving the utilities to retrieve time series and ground motion parameters; (v) implementing a tool for selecting time series in agreement with design-response spectra; (vi) compiling detailed station reports containing miscellaneous information such as photo, maps and site parameters; (vii) developing procedures for the automatic generation of station reports and for the updating of the header files. After such improvements, ITACA 1.0 was published at the web site , in 2010. It presently contains 3,955 three-component waveforms, comprising the most complete catalogue of the Italian accelerometric records in the period 1972–2007 (3,562 records) and the strongest events in the period 2008–2009. Records were mainly acquired by DPC through its Accelerometric National Network (RAN) and, in few cases, by local networks and temporary stations or networks. This paper introduces the published version of the Italian Strong Motion database (ITACA version 1.0) together with main improvements and new functionalities.     

On the application of the coupled finite-infinite element method to geodetic boundary-value problem

Our aim is to introduce the Coupled Finite-Infinite Element Method (CFIEM) as a new alternative approach to the Earth’s gravity field modelling. We show that if the computational domain is large enough in radial direction, one can obtain the qualitatively and quantitatively comparable solution to the solution by the Finite Element Method (FEM). We study the influence of the size of the computational domain on the final CFIEM solution as well as the successive refinement of the discretization and its convergence to the exact solution. As an input data we use the synthetic boundary conditions computed from a Synthetic Earth Gravity Model (SEGM) and we test the CFIEM solution by the data generated directly from SEGM and the solution by the FEM.     

Spatial variation of erosion in a small,glaciated basin in the Teton Range,Wyoming, based on detrital apatite (U‐Th)/He thermochronology

Evolution of mountain landscapes is controlled by dynamic interactions between erosional processes that vary in efficiency over altitudinal domains. Evaluation of spatial and temporal variations of individual erosion processes can augment our understanding of factors controlling relief and geomorphic development of alpine settings. This study tests the application of detrital apatite (U‐Th)/He thermochronology (AHe) to evaluate variable erosion in small, geologically complex catchments. Detrital grains from glacial and fluvial sediment in a single basin were dated and compared with a bedrock derived age‐elevation relationship to estimate spatial variation in erosion over different climate conditions in the Teton Range, Wyoming. Controls and pitfalls related to apatite quality and yield were fully evaluated to assess this technique. Probability density functions comparing detrital age distributions identify variations in erosional patterns between glacial and fluvial systems and provide insight into how glacial, fluvial, and hillslope processes interact. Similar age distributions representing erosion patterns during glacial and interglacial times suggest the basin may be approaching steady‐state. This also implies that glaciers are limited and no longer act as buzzsaws or produce relief. However, subtle differences in erosional efficiency do exist. The high frequency of apatite cooling ages from high altitudes represents either rapid denudation of peaks and ridges by mass wasting or an artifact of sample quality. A gap in detrital ages near the mean age, or mid‐altitude, indicates the fluvial system is presently transport limited by overwhelming talus deposits. This study confirms that sediment sources can be traced in small basins with detrital AHe dating. It also demonstrates that careful consideration of mineral yield and quality is required, and uniform erosion assumptions needed to extract basin thermal history from detrital ages are not always valid.     

A facies geological test of stable isotope interpretation of the Upper Permian depositional environment in West Spitsbergen

Lithofacies analysis of two transgressive sequences within the Kapp Starostin Formation (Upper Permian, West Spitsbergen), indicates considerable differences in seawater chemistry between their depositional environments. The onshore part of the sequence represented in the Vøringen and Svenskeegga Members is largely calcareous, with allochthonous and corroded siliceous materials. In contrast, in the equivalent sequence within the Hovtinden Member, silica is ubiquitous whereas carbonate materials include mainly corroded bioclasts. These differences are consistent with predictions of the oceanographic model of ‘overfed’ and ‘hungry’ oceans proposed previously on the basis of carbon and oxygen stable isotope analysis.