A monitoring system is operative in the Peschiera Springs slope (Central Apennines, Italy) to mitigate the landslide risk related to the hosted main drainage plant of Rome aqueducts by providing alert warning. Such a strategy allows to avoid out-of-service episodes so reducing extra-costs of water distribution management. The Peschiera Springs slope is involved in a rock mass creep characterized by an average steady strain rate of 1 mm year−1 and responsible for several landforms including sinkholes, subvertical scarps and trenches. Moreover, an average aquifer discharge of 19 m3 s−1 causes an intense limestone dissolution concentrated in correspondence with release bands and discontinuities that dislodge the jointed rock mass. Since 2008, an accelerometric network has been operating within the slope; about 1300 microseismic local events were recorded up to now, distinguished in failures and collapses. A control index, based on frequency of occurrence and cumulative energy of the recorded microseismic events was defined to provide three levels of alert. In 2013, a temporary nanoseismic Seismic Navigation System (SNS) array was installed inside a tunnel of the drainage plant to integrate the pre-existent seismic monitoring system. This array allowed to record 37 microseismic events, which locations are in good agreement with the evolutionary geological model of the ongoing gravitational slope deformation. In 2014, a permanent nanoseismic SNS array was installed in the plant and allowed to record several sequences of underground collapses including more than 500 events. The nanoseismic monitoring system is allowing to: (1) increase the detection level of the monitoring system; (2) locate hypocentres of the events; and (3) detect precursors of the strongest events.
A novel procedure is proposed to analyse continuous seismic signal on hourly scales to have a prompt discrimination among the different sources. Specifically, this approach is applied to a massive dataset recorded at Campi Flegrei caldera during the year 2006 when a swarm of volcano-tectonic earthquakes occurred. The convolutive independent component analysis is adopted to obtain a clear separation among meteo-marine microseism, anthropogenic noise, hydrothermal tremor in the absence of volcano-tectonic activity, whereas in non-stationary conditions a contribution connected to the corner frequency of the earthquakes emerges. A coarse-grained variable to be monitored continuously is introduced, i.e. the frequency associated with the maximum amplitude of the power spectral density of the deconvolutive independent components. That parameter is sensitive to the variation in the frequency bands of interest (e.g. that corresponding to the corner frequencies of volcano-tectonic events) and can be used as marker of the insurgence of seismic activity.
Disaster research and scholarship is now advocating a shift from focusing on the hazard event to processes that generate vulnerability and loss of resilience to disasters. Disaster legislations are among prominent instruments that can highlight the tensions as well as challenges that are being encountered towards this change in focus. Using textual analysis, this paper presents a study that investigated whether five post-2002 disaster legislations have shifted emphasis from the hazard to the vulnerability and resilience paradigms. The five examples illustrate that while there is a slight change, at least in rhetoric, from response to a prevention focus, disaster legislations largely promote a centralised institutional framework, with inadequate resource commitments and limited participation from vulnerable communities. Consequently, while generalisations simply cannot be made without a wider analysis of many more examples from different countries, the five disaster legislations appear to re-emphasise the response focus with less attention on the processes that reduce vulnerability and enhance resilience. The conclusion is that while the rhetoric has changed, the disaster legislations have not significantly moved from the hazard to vulnerability and resilience focus suggesting that reduction of losses and damages to disasters remains a big challenge 相似文献
Intestinal samples from the one-month-old Siberian mammoth calf ‘Lyuba’ were studied using light microscopy and ancient DNA to reconstruct its palaeo-environment and diet. The palynological record indicates a ‘mammoth steppe’. At least some pollen of arboreal taxa was reworked, and thus the presence of trees on the landscape is uncertain. In addition to visual comparison of 11 microfossil spectra, a PCA analysis contributed to diet reconstruction. This yielded two clusters: one of samples from the small intestine and the other of large-intestine samples, indicating compositional differences in food remains along the intestinal tract, possibly reflecting different episodes of ingestion. Based on observed morphological damage we conclude that the cyperaceous plant remains and some remains of dwarf willows were originally eaten by a mature mammoth, most likely Lyuba’s mother. The mammoth calf probably unintentionally swallowed well-preserved mosses and mineral particles while eating fecal material deposited on a soil surface covered with mosses. Coprophagy may have been a common habit for mammoths, and we therefore propose that fecal material should not be used to infer season of death of mammoths. DNA sequences of trnL and rbcL genes amplified from ancient DNA extracted from intestinal samples confirmed and supplemented plant identifications based on microfossils and macro-remains. Results from different extraction methods and barcoding markers complemented each other and show the value of longer protocols in addition to fast and commercially available extraction kits. 相似文献
