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J. Phipps Morgan C.R. Ranero P. Vannucchi 《Earth and Planetary Science Letters》2008,272(1-2):365-371
This study revisits the kinematics and tectonics of Central America subduction, synthesizing observations of marine bathymetry, high-resolution land topography, current plate motions, and the recent seismotectonic and magmatic history in this region. The inferred tectonic history implies that the Guatemala–El Salvador and Nicaraguan segments of this volcanic arc have been a region of significant arc tectonic extension; extension arising from the interplay between subduction roll-back of the Cocos Plate and the ~ 10–15mm/yr slower westward drift of the Caribbean plate relative to the North American Plate. The ages of belts of magmatic rocks paralleling both sides of the current Nicaraguan arc are consistent with long-term arc-normal extension in Nicaragua at the rate of ~ 5–10mm/yr, in agreement with rates predicted by plate kinematics. Significant arc-normal extension can ‘hide’ a very large intrusive arc-magma flux; we suggest that Nicaragua is, in fact, the most magmatically robust section of the Central American arc, and that the volume of intrusive volcanism here has been previously greatly underestimated. Yet, this flux is hidden by the persistent extension and sediment infill of the rifting basin in which the current arc sits. Observed geochemical differences between the Nicaraguan arc and its neighbors which suggest that Nicaragua has a higher rate of arc-magmatism are consistent with this interpretation. Smaller-amplitude, but similar systematic geochemical correlations between arc-chemistry and arc-extension in Guatemala show the same pattern as the even larger variations between the Nicaragua arc and its neighbors. 相似文献
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E. Mantovani M. Viti D. Babbucci D. Albarello N. Cenni A. Vannucchi 《Journal of Seismology》2010,14(1):53-65
We argue that the study of long-range interaction between seismic sources in the peri-Adriatic regions may significantly contribute
to estimating seismic hazard in Italy. This hypothesis is supported by the reconstruction of the geodynamic and tectonic settings
in the Central Mediterranean region, the space–time distribution of major past earthquakes, and the quantification of post-seismic
relaxation. The most significant evidence of long-distance interaction is recognized for the Southern Apennines, whose major
earthquakes have almost regularly followed within a few years the largest events in the Montenegro-Albania zone since 1850.
Statistical analyses of the post-1850 earthquake catalogues give a probability of about 10% that a major event in the Southern
Apennines is not preceded by the occurrence of a strong event in the Southern Dinarides–Albanides within 3–5 years. Conversely,
the probability of false alarms is relevant (50% within 3 years, 33% within 5 years). Northward, the tectonic setting and
some patterns of regularity seen in major events suggest that the seismic activation of the main transtensional decoupling
shear zones in the Central Apennines should influence the probability of major earthquakes in the Northern Apennines. 相似文献
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O. Vannucchi 《Pure and Applied Geophysics》1946,8(1-2):160-166
Riassunto Premesse le caratteristiche degli strumenti, viene esposta una statistica dell'attività dell'Osservatorio dal suo inizio, al 1 gennaio 1931, a tutto il 31 dicembre 1945.
Summary After the characteristics of the seismic instruments, is given the statistics of the activity of the Seismographics Observatory at Prato (Italy) from January 1, 1931, to December 31, 1945.相似文献
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Paola Vannucchi 《Journal of Structural Geology》1999,21(12):51
Meso- and micro-structural studies of the well-exposed Balduini Thrust (Northern Apennines, Italy) indicate that the structure formed during a single folding event, contemporaneous with diagenesis, and is a zone comprising curved, en-échelon fault segments. The geometry of each segment is arcuate with pure compression at one end and right-lateral displacement along the other. The thrust developed during the Tortonian within a single mud-rich formation, the Upper Eocene–Upper Oligocene Scaglia Cinerea, but rheological variations within the unit led to differences in deformation style; zones of scaly fabric are discontinuous and calcite veins vary in abundance. The mesoscopic morphology of the veins and the distribution of calcium carbonate along the formation indicate variations in the distribution of fluids at the time of deformation, which affected both diagenesis and the structural response of the material. Systematic variations of mechanical properties within the thickness of the Scaglia Cinerea Formation account for the curvature of the propagating thrust. Together with the heterogeneity of the stress field, the confinement of the arcing thrust to this single, weak unit lead to repeated initiation of new fractures and hence segmentation of the propagating thrust. Geometric analysis of the calcite veins and their microscopic characters suggests that hydrofracturing was involved, with the Scaglia Cinerea Formation experiencing high fluid pressure followed by rapid water expulsion. The Balduini Thrust is therefore an example of a fluid-driven, refracted compound shear zone. The analysis presented here provides insights into the three-dimensional arrangement of fault zones and fluid-migration patterns during regional faulting. 相似文献
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