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41.
Jan Lindsay Warner Marzocchi Gill Jolly Robert Constantinescu Jacopo Selva Laura Sandri 《Bulletin of Volcanology》2010,72(2):185-204
The Auckland Volcanic Field (AVF) is a young basaltic field that lies beneath the urban area of Auckland, New Zealand’s largest
city. Over the past 250,000 years the AVF has produced at least 49 basaltic centers; the last eruption was only 600 years
ago. In recognition of the high risk associated with a possible future eruption in Auckland, the New Zealand government ran
Exercise Ruaumoko in March 2008, a test of New Zealand’s nation-wide preparedness for responding to a major disaster resulting from a volcanic
eruption in Auckland City. The exercise scenario was developed in secret, and covered the period of precursory activity up
until the eruption. During Exercise Ruaumoko we adapted a recently developed statistical code for eruption forecasting, namely
BET_EF (Bayesian Event Tree for Eruption Forecasting), to independently track the unrest evolution and to forecast the most
likely onset time, location and style of the initial phase of the simulated eruption. The code was set up before the start
of the exercise by entering reliable information on the past history of the AVF as well as the monitoring signals expected
in the event of magmatic unrest and an impending eruption. The average probabilities calculated by BET_EF during Exercise
Ruaumoko corresponded well to the probabilities subjectively (and independently) estimated by the advising scientists (differences
of few percentage units), and provided a sound forecast of the timing (before the event, the eruption probability reached
90%) and location of the eruption. This application of BET_EF to a volcanic field that has experienced no historical activity
and for which otherwise limited prior information is available shows its versatility and potential usefulness as a tool to
aid decision-making for a wide range of volcano types. Our near real-time application of BET_EF during Exercise Ruaumoko highlighted
its potential to clarify and possibly optimize decision-making procedures in a future AVF eruption crisis, and as a rational
starting point for discussions in a scientific advisory group. It also stimulated valuable scientific discussion around how
a future AVF eruption might progress, and highlighted areas of future volcanological research that would reduce epistemic
uncertainties through the development of better input models. 相似文献
42.
In this paper, we illustrate a Bayesian Event Tree to estimate Volcanic Hazard (BET_VH). The procedure enables us to calculate
the probability of any kind of long-term hazardous event for which we are interested, accounting for the intrinsic stochastic
nature of volcanic eruptions and our limited knowledge regarding related processes. For the input, the code incorporates results
from numerical models simulating the impact of hazardous volcanic phenomena on an area and data from the eruptive history.
For the output, the code provides a wide and exhaustive set of spatiotemporal probabilities of different events; these probabilities
are estimated by means of a Bayesian approach that allows all uncertainties to be properly accounted for. The code is able
to deal with many eruptive settings simultaneously, weighting each with its own probability of occurrence. In a companion
paper, we give a detailed example of application of this tool to the Campi Flegrei caldera, in order to estimate the hazard
from tephra fall. 相似文献
43.
Raffaele?GrassoEmail author Marco?Cococcioni Baptiste?Mourre Jacopo?Chiggiato Michel?Rixen 《Ocean Dynamics》2012,62(3):469-493
The aim of this work is to report on an activity carried out during the 2010 Recognized Environmental Picture experiment,
held in the Ligurian Sea during summer 2010. The activity was the first at-sea test of the recently developed decision support
system (DSS) for operation planning, which had previously been tested in an artificial experiment. The DSS assesses the impact
of both environmental conditions (meteorological and oceanographic) and non-environmental conditions (such as traffic density
maps) on people and assets involved in the operation and helps in deciding a course of action that allows safer operation.
More precisely, the environmental variables (such as wind speed, current speed and significant wave height) taken as input
by the DSS are the ones forecasted by a super-ensemble model, which fuses the forecasts provided by multiple forecasting centres.
The uncertainties associated with the DSS’s inputs (generally due to disagreement between forecasts) are propagated through
the DSS’s output by using the unscented transform. In this way, the system is not only able to provide a traffic light map
(run/not run the operation), but also to specify the confidence level associated with each action. This feature was tested on a particular
type of operation with underwater gliders: the glider surfacing for data transmission. It is also shown how the availability
of a glider path prediction tool provides surfacing options along the predicted path. The applicability to different operations
is demonstrated by applying the same system to support diver operations. 相似文献
44.
Jacopo Belfi Nicolò Beverini Filippo Bosi Giorgio Carelli Angela Di Virgilio Dmitri Kolker Enrico Maccioni Antonello Ortolan Roberto Passaquieti Fabio Stefani 《Journal of Seismology》2012,16(4):757-766
The ring laser gyroscope ??G-Pisa?? has been taking data inside the Virgo interferometer central area with the aim of performing high sensitivity measurements of rotations in the vertical as well as in the horizontal orientation. We discuss the main characteristics of the instrument, describing its mechanical design and presenting the measured sensitivity limit. By applying a simple effective model for the laser gyroscope, we show that the stability of the sensor above 10?s of integration time is mainly limited by backscattering effects. The horizontal rotation rate signal is also compared with the signals recorded by the Virgo environmental monitoring system and by a biaxial mechanical tiltmeter rigidly fixed on top of the gyrolaser mounting frame. 相似文献
45.
Mauro Coltorti Jacopo Della Fazia 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(2):218-126
The Quebrada Ñaguapua alluvial fan provides a record of changes that have affected the Bolivian Chaco during the Holocene. The 4th oldest Unit, possibly related to the last glaciation, is restricted to the fan apex; it was deeply dissected during the Early Holocene, with three other units emplaced within the resultant incision. Sandy sediments characterise Unit 1 and 3 while Unit 2 is a forest soil that marks a period of stability. The oldest Unit 1 was deposited just before 6900 years BP. It contains artefacts that represent the earliest evidence of human occupation and suggests that deposition was perhaps induced by deforestation. Anthropogenic deforestation is evident at the base of Unit 3, which contains a wooden plank (140 years BP), charcoal, ash and charred tree-trunks. Some trunks have been burnt in situ while others survived the fire and are still growing, although their roots emanate from Unit 2. Although, similar events slightly to the north have been attributed to climatic changes, the delay in soil erosion in closely spaced areas could be plausibly attributed to human-induced changes. Megafaunal remains in Unit 1 represent the last occurrence of megafauna, including horse, in South America. The faunal association is anomalous because of the concurrent presence of aquatic, forest and open-environment species. We suggest that the last migrated from the southern part of Continent, where ecologic conditions allowed their survival in the Early Holocene, after the widespread clearing of the natural forest and shortly prior to the extinction of the Magafauna. 相似文献
46.
Cristiano Nicosia Roger Langohr Florias Mees Antonia Arnoldus‐Huyzendveld Jacopo Bruttini Federico Cantini 《Geoarchaeology》2012,27(2):105-122
Archaeological excavations at the Biblioteca Magliabechiana, which is part of the Uffizi gallery complex in Florence (Tuscany, central Italy), exposed Dark Earth deposits between alluvial sediments of the nearby Arno River. The term Dark Earth refers to thick, dark colored, and seemingly homogeneous deposits occurring in urban settings throughout Europe, broadly dated to the post‐Roman period. The stratigraphic sequence of the Biblioteca Magliabechiana was investigated by integrating geomorphological, chronological, and archaeological information with micromorphological and soil analytical data. This combination of approaches resulted in the identification of an early phase of Dark Earth formation (7th century A.D.) during which the area was characterized by the accumulation of manure or night soil in wet peri‐fluvial conditions. After a phase of abandonment, Dark Earth accretion resumed (10th to early 11th century A.D.), at this stage due primarily to the dumping of domestic waste. Subsequent progressive abandonment of the area was followed by the deposition of alluvium, probably during the major flood of November 4, 1177. The present study demonstrates that Dark Earth is the outcome of strong bioturbation and human reworking acting on anthropogenic deposits and possibly on alluvial sediments. 相似文献
47.
Bayesian event tree for eruption forecasting (BET_EF) at Vesuvius,Italy: a retrospective forward application to the 1631 eruption 总被引:1,自引:0,他引:1
Laura Sandri Emanuela Guidoboni Warner Marzocchi Jacopo Selva 《Bulletin of Volcanology》2009,71(7):729-745
Reliable forecasting of the next eruption at Vesuvius is the main scientific factor in defining effective strategies to reduce
volcanic risk in one of the most dangerous volcanic areas of the world. In this paper, we apply a recently developed probabilistic
code for eruption forecasting to new and independent historical data related to the pre-eruptive phase of the 1631 eruption.
The results obtained point out three main issues: (1) the importance of “cold” historical data (according to Guidoboni 2008) related to pre-eruptive phases for evaluating forecasting tools and possibly refining them; (2) the BET_EF code implemented
for Vesuvius would have forecasted the 1631 eruption satisfactorily, marking different stages of the pre-eruptive phase; (3)
the code shows that pre-eruptive signals that significantly increase the probability of eruption were likely detected more
than 2 months before the event. 相似文献
48.
Prof. Giovanni Boaga 《Pure and Applied Geophysics》1944,6(1-2):117-119
Riassunto L'A., completando alcuni suoi studi precedenti, ricava qui le espressioni normali per le deviazioni della verticale lungo meridiani e paralleli e quelle per gli scostamenti accennati nel titolo della presente Nota.
Zusammenfassung Der Verfasser, um einige seiner vorigen Arbeiten zu ergänzen, gewinnt hier die üblichen Ausdrücke für die Lothabweichungen den Meridian-und Parallelkreisen eutlang und für die im Titel dieser Note erwähnten Abweichungen.相似文献
49.
Tectonically driven deposition and landscape evolution within upland incised valleys: Ambra Valley fill,Pliocene–Pleistocene,Tuscany, Italy 下载免费PDF全文
Valeria Bianchi Massimiliano Ghinassi Mauro Aldinucci Jacopo Boaga Andrea Brogi Rita Deiana 《Sedimentology》2015,62(3):897-927
Sedimentation in the upstream reaches of incised valleys is predominantly of alluvial origin and, in most cases, independent from relative sea‐level or lake‐level oscillations. Preserved facies distributions record the depositional response to a combination of allogenic factors, including tectonics, climate and landscape evolution. Tectonics drive fluvial aggradation and degradation through local changes in gradient, both longitudinal and transverse to the valley slope. This article deals with a Pliocene–Pleistocene fluvial valley fill developed in the north‐eastern shoulder of the Siena Basin (Northern Apennines, Italy). Evolution of the valley was not influenced by sea‐level or lake‐level changes and morphological and depositional evolution of valley resulted from extensional tectonics that gave rise to normal and oblique‐slip faults orthogonal and parallel to the valley axis. Data from both field observations and geophysical study are interpreted to develop a comprehensive tectono‐sedimentary model of coeval longitudinal and lateral tilting of the developing alluvial plain. Longitudinal tilting was generated by a transverse, upstream‐dipping normal fault that controlled the aggradation of fining‐upward strata sets. Upstream of the fault zone, valley back‐filling generated an architecture similar to that of classic, sea‐level‐controlled, coastal incised valleys. Downstream of the fault zone, valley down‐filling was related to an overwhelming sediment supply sourced and routed from the active fault zone itself. Lateral tilting was promoted by the activity of a fault oriented parallel to the valley axis, as well as by different offsets along near orthogonal faults. As a result, the valley trunk system experienced complex lateral shifts, which were governed by interacting fault‐generated subsidence and by the topographic confinement of progradational, flank‐sourced alluvial fans. 相似文献
50.
Hydrogeology Journal - This study aims to determine the groundwater flow in a large area of the Venice (northeast Italy) lagoon that is under great anthropogenic pressure, which is influencing the... 相似文献