Search results for "geog"
showing 10 items of 13905 documents
Réduction de la place de la voiture à Lyon: l'acceptation sociale ne fait pas tout
2015
International audience
Motifs de démotorisation des actifs et retraités dans les aires urbaines françaises : premiers résultats statistiques de l'enquête MoDe
2021
Based on a nationwide quantitative survey conducted on 2,000 households (including 1,000 demotorised households and 1,000 non-demotorised twin households), we propose to provide an overview of demotorisation in France. This survey by questionnaire was conducted during the winter of 2017-2018 with a panel of households representative of the French population (from the Metaskope panel of Kantar-TNS ex-TNS-Sofres). Combined with the ?Parc Auto? panel survey (Kantar-TNS for Ademe-CCFA-Ifsttar-DSR), this survey is an original source of data on the French demotorised households. From two multinomial logit regression models, for both active and retired populations, this data allows to highlight th…
A Low-Cost Smartphone Sensor-Based UV Camera for Volcanic SO2 Emission Measurements
2017
Recently, we reported on the development of low-cost ultraviolet (UV) cameras, based on the modification of sensors designed for the smartphone market. These units are built around modified Raspberry Pi cameras (PiCams; ≈USD 25), and usable system sensitivity was demonstrated in the UVA and UVB spectral regions, of relevance to a number of application areas. Here, we report on the first deployment of PiCam devices in one such field: UV remote sensing of sulphur dioxide emissions from volcanoes; such data provide important insights into magmatic processes and are applied in hazard assessments. In particular, we report on field trials on Mt. Etna, where the utility of these devices in quantif…
A model of degassing for Stromboli volcano
2010
International audience; A better understanding of degassing processes at open-vent basaltic volcanoes requires collection of new datasets of H2O–CO2–SO2 volcanic gas plume compositions, which acquisition has long been hampered by technical limitations. Here, we use the MultiGAS technique to provide the best-documented record of gas plume discharges from Stromboli volcano to date. We show that Stromboli's gases are dominated by H2O (48–98 mol%; mean, 80%), and by CO2 (2–50 mol%; mean, 17%) and SO2 (0.2–14 mol%; mean, 3%). The significant temporal variability in our dataset reflects the dynamic nature of degassing process during Strombolian activity; which we explore by interpreting our gas m…
Lidar detection of carbon dioxide in volcanic plumes
2015
Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high s…
Volcanic Plume CO2 Flux Measurements at Mount Etna by Mobile Differential Absorption Lidar
2017
Volcanic eruptions are often preceded by precursory increases in the volcanic carbon dioxide (CO2) flux. Unfortunately, the traditional techniques used to measure volcanic CO2 require near-vent, in situ plume measurements that are potentially hazardous for operators and expose instruments to extreme conditions. To overcome these limitations, the project BRIDGE (BRIDging the gap between Gas Emissions and geophysical observations at active volcanoes) received funding from the European Research Council, with the objective to develop a new generation of volcanic gas sensing instruments, including a novel DIAL-Lidar (Differential Absorption Light Detection and Ranging) for remote (e.g., distal) …
Ultraviolet imaging of volcanic plumes: A new paradigm in volcanology
2017
Ultraviolet imaging has been applied in volcanology over the last ten years or so. This provides considerably higher temporal and spatial resolution volcanic gas emission rate data than available previously, enabling the volcanology community to investigate a range of far faster plume degassing processes than achievable hitherto. To date, this has covered rapid oscillations in passive degassing through conduits and lava lakes, as well as puffing and explosions, facilitating exciting connections to be made for the first time between previously rather separate sub-disciplines of volcanology. Firstly, there has been corroboration between geophysical and degassing datasets at â1 Hz, expeditin…
Le politiche di contrasto al rischio da maremoto: il caso di Stromboli
2020
This chapter, intending to be part of the reasoning on the perception of risk from extreme natural events, intends to describe the main contents of the National Emergency Plan for volcanic events of national importance on the island of Stromboli (ME) prepared in 2015 by the Department for the Civil Protection (DPC). The volcanic island of Stromboli is in fact largely exposed to the risk associated with the activities of the volcano of the same name, especially that of the tsunami. The effusive activity of the Stromboli in fact causes a marked instability of the slope known as Sciara del Fuoco which can induce, as happened at the end of 2002, a tsunami. The contribution, starting from a desc…
Evolution of Seismicity During a Stalled Episode of Reawakening at Cayambe Volcano, Ecuador
2021
Cayambe Volcano is an ice-capped, 5,790 m high, andesitic-dacitic volcanic complex, located on the equator in the Eastern Cordillera of the Ecuadorian Andes. An eruption at Cayambe would pose considerable hazards to surrounding communities and a nationally significant agricultural industry. Although the only historically documented eruption was in 1785, it remains persistently restless and long-period (LP) seismicity has been consistently observed at the volcano for over 10 years. However, the sparse monitoring network, and complex interactions between the magmatic, hydrothermal, glacial, and tectonic systems, make unrest at Cayambe challenging to interpret. In June 2016 a seismic “crisis” …
Territorio, vulnerabiliadd social y trayectoria delictiva en adolescentes de la ciudad de Valencia
2012
Se trata de una aproximación a los espacios de exclusión de la ciudad de Valencia a partir de la información sobre delincuencia juvenil y la provisión de servicios sociales. El territorio, en particular en el interior de las ciudades, es desigual. Dicha desigualdad es resultado de las características socioeconómicas de su población pero también de la oferta de servicios y equipamientos públicos. El resultado de esta compleja combinación es la existencia de espacios vulnerables y de población en riesgo de exclusión social. La delincuencia juvenil es uno de los factores que caracterizan estos territorios que, además, adolecen de galta de infraestructuras sólidas de apoyo a la población que fa…