Didattica del congiuntivo a studenti stranieri nei manuali “Espresso” e “Magari”

RECENSION

The Application of Soil-Gas Technique to Geothermal Exploration: Study of Hidden Potential Geothermal Systems

Geochemical studies were conducted using soil-gas and flux surveyings for locating both permeable zones in buried reservoirs and the presence of possible gaseous haloes linked to active geothermal systems. In this work we focused our interest on the distribution of soil-gas concentrations (Rn, Th, He, H2, O2, N2, CO2, CH4 and H2S) in the soil air of the Tetitlan area (Nayarit, Mexico) considered a potential thermal field and characterized by scarcity of surface manifestations. A total of 154 soil-gas samples and 346 CO2 and CH4 flux measurements were collected in an area of about 80 square kilometres. The performed soil-gas and flux geochemical surveys highlighted a general rising patterns linked to local fault system, with the important implication that the highest CO2 and CH4 fluxes, as well as Rn concentrations, could be used in undeveloped geothermal systems to identify main upflow regions and areas of increased and deep permeability

Earth is speaking: listen her! On-line questionnaire about anomalous geological and biological phenomena

Earthquakes can be associated with non-seismic phenomena which may manifest many weeks before and after the main shock. These phenomena are characterized by ground fractures and soil liquefactions at surface often coupled with degassing events, chemical alterations of water and soils, changes in temperature and/or waters level in the epicentral area. Further manifestations include radio disturbances and light emissions. On the other hand, anomalous behavior of animals has been reported to occur before environmental changes. The co-occurrence of several phenomena may be considered as a signal of subsurface changes, and their analysis may be used as possible forecast indicators for seismic events, landslides, damages in infrastructure (e.g., dam) and groundwaters contamination. In order to obtain an accurate statistical analysis of these factors, a pre-crisis large database over a prolonged period of time is a pre-requisite. To this end, we elaborated a questionnaire for the population to pick up signs about anomalous phenomena like as: animal behavior, geological manifestations, effect on vegetation, degassing, changes on aquifers, wells and springs. After the January 25, 2013, mainshock (ML 4.8) in the Garfagnana seismic district, the Bagni di Lucca Municipality was selected as pilot site for testing this questionnaire. The complexity, variety and extension of this territory (165 kmq) sound suitable for this project. Bagni di Lucca is located in the southern border of the Garfagnana seismogenic source, characterized by the carbonate Mesozoic sequences and the Tertiary terrigenous sedimentary deposits of the Tuscan Nappe. The questionnaire was published on Bagni di Lucca web site (https://docs.google.com/file/d/0Bzw3vOYX47XoTGltTVJRbkJuajA/edit) in collaboration with Municipal Commitee, Local Civil Protection and Local Red Cross, and sent by ordinary mail to the citizenry. It is possible to answer to the questionnaire, also anonymously, direct on line (https://docs.google.com/forms/d/1LVNVQFzMoJJfNxp2eSPAc4pcwj4_qIdbAnvbCWGyXy8/viewform?pli=1), calling the Local Civil Protection or Local Red Cross, and by mail. In a second time, an application for Smartphone and Tablets will be developed to allow a faster reply. The questionnaire, constituted by eleven questions and organized in four macro-themes (i.e. animal behavior, geological factors, vegetation anomalies and hydrogeological changes) has been published in June 2013 and will remain on-line for several years. Indeed, the social perception is not fully trustworthy during and soon after an earthquake. So far this is the first attempt to acquire data during quiescent times for comparison with post-seismic ones. This approach may provide clues to identify phenomena properly linked to the event. This questionnaire can be a useful tool to educate population not only about earthquake precursors but also to recognize the "Earth language". Submitted testimonies will be statistically analyzed evidencing the specific responses to the different phenomena in space and time. On the basis of obtained results the questionnaire project could be extended to national level

A geophysical and geochemical investigation of the Kalang-Anyar mud volcano, Indonesia

The northest Java region is a sedimentary basin as well as a promising hydrocarbon province. Like other similar setting, the region is characterized by diffused mud volcanism and degassing sites. In the Sidoarjo province extends the Watukosek Fault system that connects the Javanese Arjuno-Welirang Volcanic arc to the back-arc basin in North East Java. Along this fault systems can be identified several mud volcanoes including the spectacular Lusi mud eruption site. Approximately 40 km NE of Lusi is located the Kalang Anyar mud volcano that was target for a multidisciplinary study to understand its activity as well as the plumbing system. We combined geoelectrical, gas sampling and mapping studies and seismic monitoring. The geoelectrical data show low resistivity values (< 1 ohm.m) in the regions surrounding the mud vents until 120 m deep. Profile 1 covers the most part of the mud volcanic edifice and points out that the region of low resistivity around the vents reaches a maximum width of approximately 250 m. Overall, the three profiles held consistent results. The gas were sampled from the main vent revealing the presence of mixed as well as thermogenic methane suggesting that the more active seeps are deep rooted and connect to thermogenic methane reservoirs. CH4 and CO2 flux profiles were conducted through the active crater area and extending towards the outskirts. Results shows anomalous high values of the gasses in the summit region revealing a methane dominated diffused degassing throughout the structure. The seismic data show a drumbeat signal in the high-frequency range (i.e. between 5 Hz and 30 Hz) occurring on all the seismic stations. The signal is most pronounced on the seismic station closer to the most active emission vent. Such seismic signal is seen at regular intervals varying from about 40 s to 120 s

Continuous/discrete geochemical monitoring of CO2 Natural Analogues and of Diffuse Degassing Structures (DDS): hints for CO2 storage sites geochemical monitoring protocol

Abstract Italy is one of the most promising prone areas to study the CO 2 behavior underground, the caprock integrity to the CO 2 leakage, mostly in presence of pervious/geochemically active faults, due to a wide availability of CO 2 rich reservoirs at a depth between 1 and 10 km, as highlighted by recent literature. These deep CO 2 reservoirs generate at least 200 leakage areas at surface throughout Italy which have been defined "Diffuse Degassing Structures" (DDS) by INGV. These are widely studied by INGV institutionally by a long term convention with the Civil Protection Department (DPC) with the aim to catalog, monitor and assess the Natural Gas Hazard (NGH, namely the probability of an area to become a site of poisonous peri-volcanic gas exhalation from soils). More than 150 researcher of INGV are involved in monitoring areas affected by the CO 2 presence underground and at surface, by continuous monitoring on-line networks (around 40 stations throughout Italy, including the Etna area, Aeolian Islands, Umbria region, Piemonte region, etc.) and discretely (9 groups of research were involved in the last years to localize, define and monitor almost all the DDSs in Italy), by sampling and analyzing chemical and isotopic compounds, useful to discriminate the origin, evolution and natural gas hazards of the examined DDS. In this paper, we will discuss some DDS catalogued and studied by a Rome INGV Research Unit (UR 11) which focused its work in Central Italy, throughout different DDS, also in relation to the diverse seismotectonic settings, to discover buried faults as possible gas leakage pathways, mostly if they are "geochemically" activated. In particular we discuss, among the discrete monitoring techniques exploited by INGV, soil gas surveying, which consists in a collection of gas samples from the soil zone not saturated (dry zone) to measure the geogas gaseous species both in fluxes (CO 2 , CH 4 , 222 Rn) and in concentration (He, H 2 , H 2 S, helium, hydrogen, CO 2 , CH 4 , 222 Rn), that permeate the soil pores. The total CO 2 flux budget was calculated as "baseline" degassing rate of these " CO 2 analogues". A good discrete areal monitoring is prerequisite to design sound continuous monitoring network to monitor CO 2 related parameters in liquid/gas phases, to review the protocol of the Annex II of the European Directivity on CCS