Constraining Holocene sea levels using U‐Th ages of phreatic overgrowths on speleothems from coastal caves in Mallorca (Western Mediterranean)     

Paola Tuccimei  Michele Soligo  Joaquin Ginés  Angel Ginés  Joan Fornós  Jan Kramers  Igor Maria Villa 《地球表面变化过程与地形》2010,35(7):782-790

Phreatic overgrowths on speleothems (POS) are carbonate formations deposited at the water table of caves in unique karstic coastal settings having morphologies that can be directly related to sea level at the time of formation. The U‐Th ages of calcite and aragonite overgrowths collected from the modern water table in coastal caves on Mallorca (Cova de Cala Varques A and Cova des Pas de Vallgornera) were determined using high‐precision MC‐ICPMS techniques. U‐Th ages indicate that phreatic carbonate deposition occurred between ca 2·8 and at least 0·6 ka BP and are in accord with an archeologically estimated age of 3·7–3·0 ka BP for a drowned prehistoric construction at a depth of 1 m below current sea level in a cave from the same area. Speleothem δ¹³C and δ¹⁸O and chemical composition of cave pools provide supportive evidence that POS reflect mixing between seawater and brackish water table. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Steering of experimental channels by lateral basin tilting     

Wonsuck Kim  Ben A. Sheets  Chris Paola 《Basin Research》2010,22(3):286-301

A major issue in tectonics and sedimentation is the role of cross‐stream tectonic tilting in steering channels. The general idea is that channels will be attracted to lateral maxima in subsidence rate. A physical experiment performed in 1999 at the St. Anthony Falls Laboratory, however, was in conflict with the idea and showed that fluvial channels and resulting stratigraphy can be insensitive to even relatively strong lateral variation in subsidence. Here, we present results from an experiment which uses a simplified relay‐ramp geometry with laterally variable uplift and subsidence to test a hypothesis developed from the earlier experiment: Tectonic tilting steers channels only when the ratio of the time scales describing lateral channel mobility to tectonic deformation is sufficiently large. Occupation time by experimental channels and sand fraction in the deposit (a proxy for channel deposition) both increase with subsidence rate indicating strong steering of channels by tectonic forcing. We also found that, due to local incision, uplift lengthened the time scale for lateral channel migration relative to subsidence. Comparing channel mobility at the beginning of the experiment, with no tectonic forcing, to later tectonic stages of the experiment indicates that active tectonics increased the channel time scale. The interplay of channel steering with uplift and subsidence led to cyclic appearance and disappearance of an autogenic lake in the hanging‐wall basin. This lake was associated with alternation between channels going around vs. across the adjoining upstream uplifted footwall region. This creation and filling of the lake under constant tectonic forcing (constant fault slip rate) in the hanging wall created subaerial fan‐delta parasequences separated by fluvial deposits.  相似文献   

Improved 2-D attenuation analysis for Northern Italy using a merged dataset from selected regional seismic networks     

Paola Morasca  Marco Massa  Enrica Laprocina  Kevin Mayeda  Scott Phillips  Luca Malagnini  Daniele Spallarossa  Giovanni Costa  Paolo Augliera 《Journal of Seismology》2010,14(4):727-738

A merged, high-quality waveform dataset from different seismic networks has been used to improve our understanding of lateral seismic attenuation for Northern Italy. In a previous study on the same region, Morasca et al. (Bull Seismol Soc Am 98:1936–1946, 2008) were able to resolve only a small area due to limited data coverage. For this reason, the interpretation of the attenuation anomalies was difficult given the complexity of the region and the poor resolution of the available data. In order to better understand the lateral changes in the crustal structure and thickness of this region, we selected 770 earthquakes recorded by 54 stations for a total of almost 16,000 waveforms derived from seismic networks operating totally or partially in Northern Italy. Direct S-wave and coda attenuation images were obtained using an amplitude ratio technique that eliminates source terms from the formulation. Both direct and early-coda amplitudes are used as input for the inversions, and the results are compared. Results were obtained for various frequency bands ranging between 0.3 and 25.0 Hz and in all cases show significant improvement with respect to the previous study since the resolved area has been extended and more crossing paths have been used to image smaller scale anomalies. Quality-factor estimates are consistent with the regional tectonic structure exhibiting a general trend of low attenuation under the Po Plain basin and higher values for the Western Alps and Northern Apennines. The interpretation of the results for the Eastern Alps is not simple, possibly because our resolution for this area is still not adequate to resolve small-scale structures.  相似文献   

The 12 May 1802 earthquake (N Italy) in its historical and seismological context     

Paola Albini  Andrea Rovida 《Journal of Seismology》2010,14(3):629-651

The Mw 5.7 earthquake that occurred on 12 May 1802 is the only one with Mw ≥ 5.5 located west of Lake Garda in the central-northern part of the Po Plain, Northern Italy, and the strongest event located in the seismic zone 907 of the ZS9 seismogenic zonation of Italy. Current parametric earthquake catalogs locate the event not far from important cities (e.g., Milan) and to sites where nuclear power plants were to be built in the 1980s or could be built in a near future. Although the earthquake parameters seemed sufficiently well constrained, a detailed investigation of documentary sources was performed, in repositories storing the documents of the Napoleonic departments to which the area affected by the earthquake belonged at that time. In the surviving archival series, we found the officers’ correspondence on all the administrative aspects raised by the earthquake. The newly collected records allowed the authors to significantly increase the number of macroseismic intensity data, including new observations in the most damaged area. The results have been then interpreted in terms of both Mercalli–Cancani–Sieberg and EMS98 macroseismic scales. The earthquake parameters were derived applying two different methods in order to get two independent estimates. Earthquake location is confirmed, although the still scarce data available in the area to the east of the epicenter do not permit to reduce the uncertainty to a minimum. According to the Boxer method, the magnitude is now slightly higher, and the source model shows a good agreement with the tectonic setting of the area.  相似文献   

Reliability of the automatic procedures for locating earthquakes in southwestern Alps and northern Apennines (Italy)     

Chiara Turino  Paola Morasca  Gabriele Ferretti  Davide Scafidi  Daniele Spallarossa 《Journal of Seismology》2010,14(2):393-411

Reliable automatic procedure for locating earthquake in quasi-real time is strongly needed for seismic warning system, earthquake preparedness, and producing shaking maps. The reliability of an automatic location algorithm is influenced by several factors such as errors in picking seismic phases, network geometry, and velocity model uncertainties. The main purpose of this work is to investigate the performances of different automatic procedures to choose the most suitable one to be applied for the quasi-real-time earthquake locations in northwestern Italy. The reliability of two automatic-picking algorithms (one based on the Characteristic Function (CF) analysis, CF picker, and the other one based on the Akaike’s information criterion (AIC), AIC picker) and two location methods (“Hypoellipse” and “NonLinLoc” codes) is analysed by comparing the automatically determined hypocentral coordinates with reference ones. Reference locations are computed by the “Hypoellipse” code considering manually revised data and tested using quarry blasts. The comparison is made on a dataset composed by 575 seismic events for the period 2000–2007 as recorded by the Regional Seismic network of Northwestern Italy. For P phases, similar results, in terms of both amount of detected picks and magnitude of travel time differences with respect to manual picks, are obtained applying the AIC and the CF picker; on the contrary, for S phases, the AIC picker seems to provide a significant greater number of readings than the CF picker. Furthermore, the “NonLinLoc” software (applied to a 3D velocity model) is proved to be more reliable than the “Hypoellipse” code (applied to layered 1D velocity models), leading to more reliable automatic locations also when outliers (wrong picks) are present.  相似文献   

Healthier Geographies: Mediating the Gaps between the Needs of People Living with HIV and AIDS and Health Care in Chiang Mai,Thailand     

Vincent J. Del Casino Jr. 《The Professional geographer》2013,65(3):407-421

In this article, I contribute to our understanding of the plurality of approaches that construct the geographies of health care through an examination of the distribution of health care services for people living with HIV/AIDS (PLWHA) in Chiang Mai Province, Thailand. In particular, I focus on the development of a network of support groups for PLWHA in order to examine the differences in the sociospatial organization of these groups, the practices of social actors participating in the groups' activities, and how these activities are mediated through place-based social relations. The first section of the article analyzes the spatial distribution of PLWHA support groups in relation to the distribution of AIDS cases over two time periods, 1994 and 1997. The second section goes below the surface of the spatial distribution, examining similarities and differences in PLWHA support groups through an analysis of survey data collected on thirty-five groups in 1997. The final section deepens this examination through an analysis of ethnographic data collected on the outreach efforts of one nongovernmental organization (NGO) and one PLWHA support group with which it worked. Each section offers opportunities for the extension of our understanding of the development of PLWHA support groups, their distribution in relation to the spread of AIDS cases, and their place-based meanings.  相似文献   

A Spatio‐Temporal Graph Model for Marine Dune Dynamics Analysis and Representation     

Rémy Thibaud  Géraldine Del Mondo  Thierry Garlan  Ariane Mascret  Christophe Carpentier 《Transactions in GIS》2013,17(5):742-762

Defining a model for the representation and the analysis of spatio‐temporal dynamics remains an open domain in geographical information sciences. In this article we investigate a spatio‐temporal graph‐based model dedicated to managing and extracting sets of geographical entities related in space and time. The approach is based on spatial and temporal local relations between neighboring entities during consecutive times. The model allows us to extract sets of connected entities distant in time and space over long periods and large spaces. From GIS concepts and qualitative reasoning on space and time, we combine the graph model with a dedicated spatial database. It includes information on geometry and geomorphometric parameters, and on spatial and temporal relations. This allows us to extend classical measurements of spatial parameters, with comparisons of entities linked by complex relations in space and time. As a case study, we show how the model suggests an efficient representation of dunes dynamics on a nautical chart for safe navigation.  相似文献   

The Significance of Intestinal Parasite Remains in Pollen Samples from Medieval Pits in the Piazza Garibaldi of Parma,Emilia Romagna,Northern Italy     

Assunta Florenzano  Anna Maria Mercuri  Aurora Pederzoli  Paola Torri  Giovanna Bosi  Linda Olmi  Rossella Rinaldi  Marta Bandini Mazzanti 《Geoarchaeology》2012,27(1):34-47

This paper presents the study of parasite remains recovered in pollen samples collected from archaeological layers. Laboratory treatment enabled us to obtain very high concentrations of both pollen and parasite eggs from the same samples. The case study of the site of Piazza Garibaldi in Parma, a town in the Po plain, is reported. The site was a sacred area in Roman times and a market square in Medieval times (10th–11th century A.D.). Pollen, seeds, and fruits from the latter phase were collected from four Medieval pits and one cesspit. After a palynological treatment including sieving, floating, and light acetolysis, abundant quantities of parasite eggs were extracted. Human and animal parasite eggs belonging to Trichuris, Ascaris, Taenia/Echinococcus, Capillaria, Dicrocoelium, and Diphyllobothrium were found. The analyses of animal and plant remains identified in the same samples suggested that the pit infillings consisted of waste, human and animal excrements, deteriorated plant food, and refuse of grapes. Therefore, parasite remains help the interpretation of archaeobotanical data in identifying human behaviors and site functions.  相似文献   

Macroseismic effects highlight site response in Rome and its geological signature     

Paola Sbarra  Valerio De Rubeis  Emiliano Di Luzio  Marco Mancini  Massimiliano Moscatelli  Francesco Stigliano  Patrizia Tosi  Roberto Vallone 《Natural Hazards》2012,62(2):425-443

A detailed analysis of the earthquake effects on the urban area of Rome has been conducted for the L??Aquila sequence, which occurred in April 2009, by using an online macroseismic questionnaire. Intensity residuals calculated using the mainshock and four aftershocks are analyzed in light of a very accurate and original geological reconstruction of the subsoil of Rome based on a large amount of wells. The aim of this work is to highlight ground motion amplification areas and to find a correlation with the geological settings at a subregional scale, putting in evidence the extreme complexity of the phenomenon and the difficulty of making a simplified model. Correlations between amplification areas and both near-surface and deep geology were found. Moreover, the detailed scale of investigation has permitted us to find a correlation between seismic amplification in recent alluvial settings and subsiding zones, and between heard seismic sound and Tiber alluvial sediments.  相似文献   

Nitrate source and fate at the catchment scale of the Vibrata River and aquifer (central Italy): an analysis by integrating component approaches and nitrogen isotopes   总被引：1，自引：0，他引：1  

Tiziana Di Lorenzo  Mauro Brilli  Dina Del Tosto  Diana M. P. Galassi  Marco Petitta 《Environmental Earth Sciences》2012,67(8):2383-2398

The aim of this study is to apply an integrated approach to determine nitrate sources and fate in the alluvial aquifer of the River Vibrata (Abruzzi, central Italy) by coupling the Isotope and the Component approaches. Collected data include concentration and nitrogen isotope composition of groundwater samples from the alluvial aquifer and nitrogen loads arising from agricultural and non-agricultural sources. The adopted methodology identified synthetic fertilizers as main sources of nitrate in the Vibrata alluvial aquifer. At the catchment scale, two different zones have been identified: the Upper Valley, where infiltration to groundwater is dominant and nitrogen easily migrates into the aquifer; in this area, nitrate content in groundwater is stable and normally higher than EU requirements. Moreover, streamwaters are fed by groundwater with a nitrate content likely lowered by denitrification processes occurring in the hyporheic zone. In the Lower Valley, runoff processes dominate and the nitrate content in surface waters is higher. Nevertheless, groundwater is locally affected by denitrification that breaks down the nitrate content, which often reaches values consistent with law limits.  相似文献