Holocene mass‐wasting events in Lago Fagnano,Tierra del Fuego (54°S): implications for paleoseismicity of the Magallanes‐Fagnano transform fault     

Nicolas Waldmann  Flavio S. Anselmetti  Daniel Ariztegui  James A. Austin  Jr  Mortaza Pirouz  Christopher M. Moy  Robert Dunbar 《Basin Research》2011,23(2):171-190

High‐resolution seismic imaging and coring in Lago Fagnano, located along a plate boundary in Tierra del Fuego, have revealed a dated sequence of Holocene mass‐wasting events. These structures are interpreted as sediment mobilizations resulting from loading of the slope‐adjacent lake floor during mass‐flow deposition. More than 19 mass‐flow deposits have been identified, combining results from 800 km of gridded seismic profiles used to site sediment cores. Successions of up to 6‐m thick mass‐flow deposits, pond atop the basin floor and spread eastward and westward following the main axis of the eastern sub‐basin of Lago Fagnano. We developed an age model, on the basis of information from previous studies and from new AMS‐¹⁴C ages on cored sediments, which allows us to establish a well‐constrained chronologic mass‐wasting event‐catalogue covering the last ～12 000 years. Simultaneously triggered, basin‐wide lateral slope failure and the formation of multiple debris flow and postulated megaturbidite deposits are interpreted as the fingerprint of paleo‐seismic activity along the Magallanes‐Fagnano transform fault that runs along the entire lake basin. The slope failures and megaturbidites are interpreted as recording large earthquakes occurring along the transform fault since the early Holocene. The results from this study provide new data about the frequency and possible magnitude of Holocene earthquakes in Tierra del Fuego, which can be applied in the context of seismic hazard assessment in southernmost Patagonia.  相似文献   

Horizontal accuracy assessment of very high resolution Google Earth images in the city of Rome,Italy     

Giuseppe Pulighe  Valerio Baiocchi  Flavio Lupia 《International Journal of Digital Earth》2016,9(4):342-362

Google Earth (GE) has recently become the focus of increasing interest and popularity among available online virtual globes used in scientific research projects, due to the free and easily accessed satellite imagery provided with global coverage. Nevertheless, the uses of this service raises several research questions on the quality and uncertainty of spatial data (e.g. positional accuracy, precision, consistency), with implications for potential uses like data collection and validation. This paper aims to analyze the horizontal accuracy of very high resolution (VHR) GE images in the city of Rome (Italy) for the years 2007, 2011, and 2013. The evaluation was conducted by using both Global Positioning System ground truth data and cadastral photogrammetric vertex as independent check points. The validation process includes the comparison of histograms, graph plots, tests of normality, azimuthal direction errors, and the calculation of standard statistical parameters. The results show that GE VHR imageries of Rome have an overall positional accuracy close to 1 m, sufficient for deriving ground truth samples, measurements, and large-scale planimetric maps.  相似文献   

Monitoring of a methane-seeping pockmark by cabled benthic observatory (Patras Gulf, Greece)     

Giuditta Marinaro  Giuseppe Etiope  Nadia Lo Bue  Paolo Favali  George Papatheodorou  Dimitris Christodoulou  Flavio Furlan  Francesco Gasparoni  George Ferentinos  Michel Masson  Jean-François Rolin 《Geo-Marine Letters》2006,26(5):297-302

A new seafloor observatory, the gas monitoring module (GMM), has been developed for continuous and long-term measurements of methane and hydrogen sulphide concentrations in seawater, integrated with temperature (T), pressure (P) and conductivity data at the seafloor. GMM was deployed in April 2004 within an active gas-bearing pockmark in the Gulf of Patras (Greece), at a water depth of 42 m. Through a submarine cable linked to an onshore station, it was possible to remotely check, via direct phone connection, GMM functioning and to receive data in near-real time. Recordings were carried out in two consecutive campaigns over the periods April–July 2004, and September 2004–January 2005, amounting to a combined dataset of ca. 6.5 months. This represents the first long-term monitoring ever done on gas leakage from pockmarks by means of CH₄+H₂S+T+P sensors. The results show frequent T and P drops associated with gas peaks, more than 60 events in 6.5 months, likely due to intermittent, pulsation-like seepage. Decreases in temperature in the order of 0.1–1°C (up to 1.7°C) below an ambient T of ca. 17°C (annual average) were associated with short-lived pulses (10–60 min) of increased CH₄+H₂S concentrations. This seepage “pulsation” can either be an active process driven by pressure build-up in the pockmark sediments, or a passive fluid release due to hydrostatic pressure drops induced by bottom currents cascading into the pockmark depression. Redundancy and comparison of data from different sensors were fundamental to interpret subtle proxy signals of temperature and pressure which would not be understood using only one sensor.  相似文献   

The State of the Adriatic Sea Centered on the Small Pelagic Fish Populations   总被引：1，自引：0，他引：1  

Massimo Azzali  rea De  Felice  Manlio Luna  Giulio Cosimi  Flavio Parmiggiani 《Marine Ecology》2002,23(S1):78-91

Abstract. The paper provides an overview of the state of the small pelagic fish in the Adriatic Sea. The North Adriatic is reviewed for the 1976–1998 period and the South Adriatic for the 1987–1998 period. First the fluctuations in time and in space of the pelagic biomass, as a whole and per species, are presented. Then the dramatic collapse of anchovy stock and its apparent association with the decrease of surface temperature is discussed. Finally the changes of the anchovy and sardine catches are compared and analysed with respect to their abundances in the sea. The conclusion is that acoustic and satellite methods are able to provide a large amount of information on the variability in the pelagic populations; this is essential for an appropriate management of these resources. There is still a need, however, to refine the methods and to integrate this kind of information with further environmental data (including natural predators).  相似文献   

Brain acetylcholinesterase as a marine pesticide biomarker using Brazilian fishes     

Oliveira MM  Silva Filho MV  Cunha Bastos VL  Fernandes FC  Cunha Bastos J 《Marine environmental research》2007,63(4):303-312

Brain acetylcholinesterase (AChE) of some fishes from the coast of Rio de Janeiro State was studied as a possible pesticide biomarker in marine environmental monitoring. AChE specific activity in brain varied from 145 to 530 U/g of proteins and the Michaelis-Menten constant (K(M)) for acetylthiocholine varied from 104 to 291 microM among the 20 species studied. The enzyme sensitivity to methyl paraoxon, evaluated by the inhibition kinetic constants, shows that some species (Paralonchurus brasiliensis and Genidens genidens) are more sensitive (IC50-30 min=455 and 468 nM, respectively). The less sensitive Merluccius hubbsi and Percophis brasiliensis (IC50-30 min=3339 and 3259 nM, respectively) belong to the super-order Paracanthopterygii, which includes the more ancient species. On the other hand, more susceptible species belong to the super-order Acanthopterygii, which includes more recent species. These results suggest a possible evolutionary linkage for AChE sensitivity to methyl paraoxon. The application of inhibition kinetic constants for fish brain AChE in phylogenetic studies is still being investigated. The results have shown that a fish sentinel species should have the highest brain AChE level among the more sensitive ones.  相似文献   

The evaluation of volcanic risk in the Vesuvian area     

Roberto Scandone  Giovanni Arganese  Flavio Galdi 《Journal of Volcanology and Geothermal Research》1993,58(1-4)

Volcanic Risk has been defined as the product: R = Value × Vulnerability × Hazard, where value is the total amount of lives or properties at risk for a volcani eruption, the vulnerability is the percentage of value at risk for a given volcanic event, and the hazard is the probability that a given area may be affected by a certain volcanic phenomenon.We used this definition to evaluate the Risk of loss of human lives for volcanic eruptions of Vesuvius. Value has been determined based on the total number of inhabitants living in areas that could be affected by an eruption. Vulnerability is based on the relative probability of deaths as a result of different volcanic phenomena (tephra fall, pyroclastic flows, etc.). Hazard is evaluated based on the absolute probability of a given phenomenon in a certain area. This last parameter is the most difficult to evaluate.We subdivided the activity of Vesuvius, that produces risk of loss of human lives, into three classes of eruptions, based on the Volcanic Explosivity Index. We assume that the events of each class are distributed according to a poissonian distribution (this is demonstrated for VEI = 3, and inferred for the other classes), so that we can evaluate the absolute probability of an eruption for each class within a given time span. We use a time window of 10 years and evaluate the probabilities of occurrence of at least one eruption for VEI = 3, 4, 5; the probability is respectively: P₃ = 0.09896, P₄ = 0.01748, P₅ = 0.00298We have made a hazard evaluation for the entire Vesuvian area as well as an evaluation of Volcanic Risk.The obtained map shows that the areas with higher risk are on the southern side of Vesuvius, in the coastal region where each town is characterized by an average Risk of 1000 inhabitants/10 years. The risk regularly decreases with increasing distance from the volcano. The risk is mostly due to the events with VEI = 3 and 4, as the most destructive effects of VEI = 5 are counterbalanced by the lower probability of such events.The map of volcanic risk is not intended to predict the loss of human lives of an eruption, but to give a methodology that permits to identify those areas where it is necessary to operate in order to reduce the risk of an eruption before it occurs.  相似文献   

L'orage en Suisse     

Flavio Ambrosetti  Max Bider  Max Bouët 《Theoretical and Applied Climatology》1957,8(2):172-184

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High-temperature rapid pyrometamorphism induced by a charcoal pit burning: The case of Ricetto,central Italy     

Flavio?CapitanioEmail author  Francesco?Larocca  Salvatore?Improta 《International Journal of Earth Sciences》2004,93(1):107-118

Bulk chemistry and mineralogy of the peculiar rock of Ricetto (Carseolani Mts., Central Apennines, Italy) was studied to resolve its controversial origin: igneous dyke or anthropic product. This hybrid rock consists of a colorless, felsic component made up of glass plus quartz, and a brown, femic component made up of fans and spherulites of diopside, calcic plagioclase, wollastonite, and melilite. Textural relationships indicate very rapid cooling and immiscibility phenomena. The bulk chemistry of the rock is the same as that of the surrounding siliciclastic sandstone. The ¹⁴C analysis of a coal fragment from bottom of the body yields the conventional age of 227(±50) years. The Ricetto occurrence is an example of pyrometamorphism of a siliceous limestone induced by a charcoal pit burning. The small size of the heat source at Ricetto caused an intense but short-lived melting of the country rock. Prograde metamorphism caused a temperature increase up to 1,000–1,100 °C when melilite crystallization conditions were reached at appreciable P(CO₂) and high f(O₂). Melting occurred in a close system represented by the simplified equation: 3Cal+16.5Qtz+Ms+BtMel+Melt+2H₂O+3CO₂+0.5O₂. Diopside+calcic plagioclase+wollastonite formed by melilite breakdown during rapid cooling, through the reaction: 6Mel+6Qtz+0.5O₂3Di+2An+7Wo. Liquid immiscibility caused the separation between the felsic melt component and the femic melilite-bearing component. Immiscibility was characterized by different fractionation of alumina and alkalies between these two phases. Differences in bulk, glass, and mineral chemistry between the Ricetto and other melilite-bearing pyrometamorphic rocks can be attributed mainly to different protoliths.An erratum to this article can be found at  相似文献   

The record of historic earthquakes in lake sediments of Central Switzerland   总被引：1，自引：0，他引：1  

Katrin Monecke  Flavio S. Anselmetti  Arnfried Becker  Michael Sturm  Domenico Giardini 《Tectonophysics》2004,394(1-2):21-40

Deformation structures in lake sediments in Central Switzerland can be attributed to strong historic earthquakes. The type and spatial distribution of the deformation structures reflect the historically documented macroseismic intensities thus providing a useful calibration tool for paleoseismic investigations in prehistoric lake sediments.The Swiss historical earthquake catalogue shows four moderate to strong earthquakes with moment magnitudes of M_w=5.7 to M_w=6.9 and epicentral intensities of I₀=VII to I₀=IX that affected the area of Central Switzerland during the last 1000 years. These are the 1964 Alpnach, 1774 Altdorf, 1601 Unterwalden, and 1356 Basel earthquakes. In order to understand the effect of these earthquakes on lacustrine sediments, four lakes in Central Switzerland (Sarner See, Lungerer See, Baldegger See, and Seelisberg Seeli) were investigated using high-resolution seismic data and sediment cores. The sediments consist of organic- and carbonate-rich clayey to sandy silts that display fine bedding on the centimeter to millimeter scale. The sediments are dated by historic climate and environmental records, ¹³⁷Cs activity, and radiocarbon ages. Deformation structures occur within distinct zones and include large-scale slumps and rockfalls, as well as small-scale features like disturbed and contorted lamination and liquefaction structures. These deformations are attributed to three of the abovementioned earthquakes. The spatial distribution of deformation structures in the different lakes clearly reflects the historical macroseismic dataset: Lake sediments are only affected if they are situated within an area that underwent groundshaking not smaller than intensity VI to VII. We estimate earthquake size by relating the epicentral distance of the farthest liquefaction structure to earthquake magnitude. This relationship is in agreement with earthquake size estimations based on the historical dataset.  相似文献   

15,000 Years of mass-movement history in Lake Lucerne: Implications for seismic and tsunami hazards   总被引：2，自引：0，他引：2  

Michael Schnellmann  Flavio S. Anselmetti  Domenico Giardini  Judith A. Mckenzie 《Eclogae Geologicae Helvetiae》2006,99(3):409-428

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