1,720,976 research outputs found
Volcanic structure of the southern sector of Mt Etna after the 2001 and 2002 eruptions defined by magnetotelluric measurements.
No full textTwo magnetotelluric (MT) surveys were carried out on the Mt. Etna volcano after two of the most intense eruptions of the last 30 years which took place in summer 2001 and winter 2002-2003. Surveying was pursued for two main reasons. First, we sought to contribute to the definition of the first-order structure and physico-chemical state (temperature, fluids, melts) of a volcano that has been extensively explored and monitored by means of various geophysical methods, but where only few electrical and electromagnetic surveys have been performed. Secondly, we acquired MT data in the same sites in the two different surveys with the aim of monitoring the possible changes of the first-order structure, since conditions are expected to vary on an active volcano such as Etna, and are supposed to be linked to the eruptive events. Soundings have been acquired in an E-W 10 km-long profile across the southern flank of Mt. Etna, at a distance of almost 6 km south from the Central Crater. The first survey was carried out three months after the 2001 eruption. Inverse models define a pronounced (4 km thickness) low resistivity section at a depth of about 1 km b.s.l. to the west. To the east, a low resistivity section is still present, but appears deeper, thinner and more resistive, and a shallow low resistivity anomaly also exists. The shallow anomaly to the east is tentatively correlated with altered and clayey volcanic units and/or temporary groundwater storage. The deep anomalies are interpreted as being due to melt storage at shallow depths which was not exhausted during the eruption. This would be confirmed by the abundance of lava erupted within one year from the end of the survey. The few good sites retrieved in the second survey, carried out a few weeks after the eruption of 2002-2003, confirm the picture defined in the first survey, and provide a better definition of the bottom of the deep anomaly located in the sedimentary basement
Magnetotelluric survey at the Alps-Apennines boundary (Tertiary Piemonte Basin - north/western Italy)
No full textDeterminazione della velocità e della direzione di deflusso di una falda freatica in un sito dell'alta pianura veneta mediante l'impiego di metodologie geofisiche
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Nuovi contributi sull'inquinamento della falda freatica nella pianura alluvionale a sud di Verona
No full textTwo-dimensional analysis of a magnetotelluric profile in the CROP03 area in Southern Tuscany.
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Mapping the geometry of an aquifer system with a high resolution reflection seismic profile.
No full textA high-resolution P-wave seismic reflection survey was conducted in the area of Lambro Park within the city of Milan (northern Italy). Several high permeability channel sequences were identified and the stratigraphy of the infill was accurately mapped. The seismic signature imaged a previously undefined unit and also established the lateral correlation of some depositional units within the three major aquifer groups along the survey line. The complexity of the acoustic framework and the reduced depth of the source location limited effective elastic-wave generation. The geological setting also caused propagation of strong coherent noise patterns. Further interference, observed in the recorded data, was due to the traffic noise from the nearby highway. The attenuation of the undesired events required the design of specific filters and their multistep implementation. The results of forward modelling based on borehole information and of noise tests were crucial factors in the design of the processing parameters and in the stratigraphic interpretation of the final stacked sectio
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