1,721,023 research outputs found
Caratteri geofisici delle strutture crostali nella provincia geotermica toscana
No full textSTUDI GEOLOGICI CAMERT
Crust and upper mantle structural properties along the active Tyrrhenian rim
No full textThe volcanic complexes from the Eolian islands to the Campania/Roman regions and Tuscany further north, rest on lithospheric sectors which overlie the Adriatic continental lithosphere sinking along the Apennine-Maghrebian orogenic belt. Evidence for this stems from the melting, at mantle depth, of upper crustal material as evidenced by the widespread interaction of S-type and K-alkaline melts. The genesis of atypical magmas of the Roman Province (central-southern Italy) appears to be the result of an important block faulting and deep lithospheric rifting of the Apennine continental margin lying parallel and above relic sinking slabs. Intermediate and deep-focus earthquakes indicate that the lithospheric slab is still seismically active under the Eolian-Calabrian area and, sporadically, at the southern end of Campania. On the other end, in the Roman/Tuscan region, it seems to be almost inactive, few earthquakes having been located with hypocentral depths not exceeding 150 km. The existence of lithospheric slabs along the Tyrrhenian rim is supported by surface wave dispersion and scattering measurements as well as P-waves residuals, and is confirmed by the trend of long-wavelengths gravity anomalies, interpreted within the geometrical constraints imposed by aeromagnetic and seismic data. The analysis of the spectral content of seismic sources supports the existence of two zones of lithospheric shortening in correspondence of Tuscany and South Tyrrhenian sea which are separated by a tensional region extending from Latium to Calabry
Sismogrammi sintetici applicati alla definizione della distribuzione in profondita' della velocita' delle onde S ed esperimenti DSS
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Modellazione fine dei parametri elastici ed anelastici della crosta terrestre mediante sismogrammi sintetici
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Aeromagnetic constraints on the geostructural interpretation of the southern part of the Sardinian rift (Italy)
No full textThe Nanga Parbat-Haramosh monitoring network.
No full textIf the Himalayas are a land of extremes from the topographical, geophysical and
geological point of view (Windley, 1984, 1988), the Karakorum is a land of superlatives, having the
highest concentration of mountains over 8000 metres, having the longest glaciers outside of the
poles, being the source of one of the longest rivers. From the geophysical point of view it contains
the largest gravity anomalies (Poretti et al., 1983) and thickness of the earth crust (75 km) (Finetti
et al., 1978, 1983) and the highest values of deflection of the vertical. It also contains the highest
relief (4000 metres from the Indus plains to the summit of Nanga Parbat). It seems also that this
area is subject to the highest uplift. This has been mentioned by many authors who derived it through indirect methods, but had not yet been confirmed by accurate direct observations. Lewis
Owen reports 0.7 mm/y using fission-track methods (Owen, 1981). Higher values (2 mm/y) are
inferred by several researchers (Zeitler 1985, Gorniz and Seeber 1981; Lyon-Caen and Molnar
1983; Ferguson, 1985 and again Owen, 1989). Finally an average value of 6-10 mm/y was in the
hypothesis of Zeitler et al. 1985 including uplift and erosion. These values were calculated through
indirect methods, but no tentative was made to calculate the uplift of the Nanga Parbat - Haramosh
massif through direct surveys. The present study shows the preliminary results of a first survey consequent
to the installation of a GNSS network including three permanent GNSS stations between
Islamabad and the Northern Areas of Pakistan and four points located on the Nanga Parbat –
Haramosh massif. These points will be surveyed once a year during the next 6 years and will provide
a fair record of their movements, both horizontal and vertical, with respect to the surrounding
areas. During the processing of the surveyed data, the observations of the International GPS Network
Kit3 situated at in Uzbekistan will be taken into account. Another problem tackled by this
research is the determination of the stability of the two banks of the Indus river in the area where
the Diamer Basha dam is being built. The repeated measurements, before, during and after the construction
of the dam will be an important index of the change in the geophysical parameters produced
by the dam and the related lake. GPS and classical distance measurements will be performed
on a network of 6 points located on both sides of the river
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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