排序方式： 共有55条查询结果，搜索用时 15 毫秒
51.
Itziar Aretxaga David H. Hughes Kristen Coppin Angela M. J. Mortier Jeff Wagg James S. Dunlop Edward L. Chapin Stephen A. Eales Enrique Gaztañaga Mark Halpern Rob J. Ivison Eelco van Kampen Douglas Scott Stephen Serjeant Ian Smail Thomas Babbedge rew J. Benson Scott Chapman David L. Clements Loretta Dunne Simon Dye Duncan Farrah Matt J. Jarvis Robert G. Mann Alexandra Pope Robert Priddey Steve Rawlings Marc Seigar Laura Silva Chris Simpson Mattia Vaccari 《Monthly notices of the Royal Astronomical Society》2007,379(4):1571-1588
52.
Hydrogeological Changes Related to the Umbria–Marche Earthquake of 26 September 1997 (Central Italy)
Evidences of variations of the hydrologic regime have been observed after the Umbria–Marche seismic sequence, started on September 26th 1997, at the boundary between Umbria and Marche regions, central Italy. In order to quantify the hydrological variations, several data regarding groundwater level, spring discharge and river flow rates, have been collected from local authorities and mineral water companies. They allowed to confine the area affected by anomalies and to quantify the hydrological variations by a comparison with the average yearly regime, estimated from the data referring to previous years. An attempt to identify precursor phenomena has also been carried out. The results of the analysis sustain the close connection of two water reservoirs, the Umbria–Marche ridge and the Valnerina unit, that have both been affected by changes of the hydrologic regime. Two of the river gauge stations registered anomalies several months before the crisis started, acting as earthquake precursors. 相似文献
53.
A.?BonaccorsoEmail author S.?D’Amico M.?Mattia D.?Patanè 《Pure and Applied Geophysics》2004,161(7):1469-1487
In this work we present seismological and ground deformation evidence for the phase preparing the July 18 to August 9, 2001 flank eruption at Etna. The analysis performed, through data from the permanent seismic and ground deformation networks, highlighted a strong relationship between seismic strain release at depth and surface deformation. This joint analysis provided strong constraints on the magma rising mechanisms. We show that in the last ten years, after the 1991–1993 eruption, an overall accumulation of tension has affected the volcano. Then we investigate the months preceding the 2001 eruption. In particular, we analyse the strong seismic swarm on April 20–24, 2001, comprising more than 200 events (Mmax = 3.6) with prevalent dextral shear fault mechanisms in the western flank. The swarm showed a ca. NE-SW earthquake alignment which, in agreement with previous cases, can be interpreted as the response of the medium to an intrusive process along the approximately NNW-SSE volcano-genetic trend. These mechanisms, leading to the July 18 to August 9, 2001 flank eruption, are analogous to ones observed some months before the 1991–1993 flank eruption and, more recently, in January 1998 before the February-November 1999 summit eruption. 相似文献
54.
Structure of the lithosphere beneath the Eastern Alps (southern sector of the TRANSALP transect) 总被引：1，自引：0，他引：1
Alberto Castellarin Rinaldo Nicolich Roberto Fantoni Luigi Cantelli Mattia Sella Luigi Selli 《Tectonophysics》2006,414(1-4):259
The interpretation of the seismic Vibroseis and explosive TRANSALP profiles has examined the upper crustal structures according to the near-surface geological evidences and reconstructions which were extrapolated to depth. Only the southern sector of the TRANSALP transect has been discussed in details, but its relationship with the whole explored chain has been considered as well. The seismic images indicate that pre-collision and deep collision structures of the Alps are not easily recognizable. Conversely, good records of the Neo-Alpine to present architecture were provided by the seismic sections.Two general interpretation models (“Crocodile” and “Extrusion”) have been sketched by the TRANSALP Working Group [2002]. Both illustrate the continental collision producing strong mechanical interaction of the facing European and African margins, as documented by giant lithosphere wedging processes. Arguments consistent with the “Extrusion” model and with the indentation of Adriatic (Southalpine) lithosphere underneath the Tauern Window (TW) are:
- – According to the previous DSS reconstructions, the Bouguer anomalies and the Receiver Functions seismological data, the European Moho descends regularly attaining a zone south of the Periadriatic Lineament (PL). The Moho boundary and its geometry appear to be rather convincing from images of the seismic profile;
- – the Tauern Window intense uplift and exhumation is coherent with the strong compression regime, which acted at depth, thus originating the upward and lateral displacement of the mobile and ductile Penninic masses according to the “Extrusion” model;
- – the indentation of the Penninic mobile masses within the colder and more rigid Adriatic crust cannot be easily sustained. Wedging of the Adriatic stiffened lower crust, under high stresses and into the weaker Penninic domain, can be a more suitable hypothesis. Furthermore, the intrusion of the European Penninic crustal wedge underneath the Dolomites upper crust is not supported by any significant uplifting of the Dolomites. The total average uplift of the Dolomites during the Neogene appears to be 6−7 times smaller than that recognized in the TW. Markedly the northward dip of the PL, reaching a depth of approximately 20 km, is proposed in our interpretation;
- – finally, the Adriatic upper crustal evolution points to the late post-collision change in the tectonic grow-up of the Eastern Alps orogenic chain. The tectonic accretion of the northern frontal zone of the Eastern and Central Alps was interrupted from the Late Miocene (Serravallian–Tortonian) onward, as documented by the Molasse basin evolution. On the contrary, the structural nucleation along the S-vergent tectonic belt of the eastern Southern Alps (Montello–Friuli thrust belt) severely continued during the Messinian and the Plio–Pleistocene. This structural evolution can be considered to be consistent with the deep under-thrusting and wedge indentation of the Adriatic lithosphere underneath the southern side of the Eastern Alps thrust-and-fold belt.
55.
Accurate 3D surface measurement of mountain slopes through a fully automated image-based technique 总被引：1，自引：1，他引：0
In this paper an automated procedure for surface reconstruction that can be used for surveying and monitoring rock and ground slopes is presented. This method has been developed for geological and engineering applications, where accuracy and completeness are factors of primary importance for the final 3D model, which must provide a detailed metric survey and not only a visual reconstruction of the scene. The proposed procedure integrates two image matching techniques. The first one is used to automatically extract a set of tie points that are needed for computing the exterior orientation parameters of all images through a photogrammetric bundle adjustment. Such tie oints are also exploited to obtain a preliminary seed model that is then enriched based on Multi-photo Least Squares Matching. During this second stage, the surface model is improved in terms of point density and accuracy. Different strategies were implemented to successfully combine both techniques, along with some new improvements. The presented procedure has been tested in two different applications: geometric modelling of rock cliffs and evaluation of weathering of a ground slope. In both cases the obtained results presented accuracy sufficient for geological investigation. Moreover, outcomes were comparable to the ones from laser scanning surveying and other photogrammetric implementations. 相似文献