Dynamics of a seismogenic fault subject to variable strain rate

Abstract. The behaviour of seismogenic faults is generally investigated under the assumption that they are subject to a constant strain rate. We consider the effect of a slowly variable strain rate on the recurrence times of earthquakes generated by a single fault. To this aim a spring-block system is employed as a low-order analog of the fault. Two cases are considered: a sinusoidal oscillation in the driver velocity and a monotonic change from one velocity value to another. In the first case, a study of the orbit of the system in the state space suggests that the seismic activity of the equivalent fault is organized into cycles that include several earthquakes and repeat periodically. Within each cycle the recurrence times oscillate about an average value equal to the recurrence period for constant strain rate. In the second case, the recurrence time changes gradually from the value before the transition to the value following it. Asymptotic solutions are also given, approximating the case when the amplitude of the oscillation or of the monotonic change is much smaller than the average driver velocity and the period of oscillation or the duration of the transition is much longer than the recurrence times of block motions. If the system is not isolated but is subject to perturbations in stress, the perturbation anticipates or delays the subsequent earthquake. The effects of stress perturbations in the two cases of strain rate oscillations and monotonic change are considered

Structural control on carbon emissions at the Nirano mud volcanoes – Italy

The Nirano Salse in Italy is a well-studied site where natural gas seepage (NGS) and other hydrocarbon fluids and gases are emitted at the earth's surface. A novel integrated approach is applied to define a comprehensive structural interpretation of the gas seepage and flow dynamic in the mud volcano system of the Nirano Salse Regional Nature Reserve (Modena, Northern Apennines). The paper investigates the relationship between gas emissions and local structures, particularly faults and fractures, in the shallow subsurface (down to 500–600 m depth) to understand the control that structures have on fluid ascent from deep leaky hydrocarbon traps. We performed continuous monitoring of mud levels within vents; carried out geological surveys to characterize the main stratigraphic and structural discontinuities; measured the carbon emissions (CH4 and CO2) seepage both from volcanoes and the surrounding soil by a portable gas fluxmeter; and integrated the results with available geophysical surveys. The authors argue that the transgressive Pleistocene-Pliocene Argille Azzurre Formation hides the complex and highly structured pre-Pliocene geology of the area, in which faults and fractures act as pathways for deep fluid ascent. The emissions are aligned along a NE-SW trend at the intersection of a NE-SW fracture system and NW-SE-oriented normal faults, which are both associated to the local tensional stress field of a likely left-lateral strike-slip transfer structure or in the extrados of a fold. By examining both natural gas macroseepage and diffuse flux, it is shown that local structures control the fluid ascent and contribute to the emission of hydrocarbon gases and fluids at the Earth's surface. Understanding the structural control of carbon emissions at the Nirano Salse is also important for evaluating the carbon budget at the site, particularly in areas where there are detectable surface emissions. The study has implications for geologic, environmental, and economic issues, including hydrocarbon exploration, hazard assessment, and impact on the atmospheric carbon budget. Furthermore, the outcomes have an important implication to evaluate the potential for dangerous abrupt mud eruptions, and the site safety in proximity to the mud volcanoes

The microbiota of Idaea inquinata developing on dry herbs

Idaea inquinata (Scopoli) (Lepidoptera: Geometridae, Idaeini) is a potential pest of stored food, mainly dry herbs. In this study, the role of diet in the shaping of the I. inquinata-associated bacterial community was investigated and its impact on insect performance (i.e., proportion of adult emergence and duration of postembryonic development). Larvae were reared on three diets with different nutritional compositions: (1) Matricaria chamomilla L. flowers, (2) Angelica archangelica L. roots, and (3) artificial diet. A DNA metabarcoding approach targeting V1-V2 and V4 regions of the bacterial 16S rRNA was adopted to characterize the bacterial communities associated with adults and larvae reared on different diets, and estimate their composition and diversity. The core microbiota of this species was found to include some bacterial genera commonly associated with Lepidoptera. When a coverage-based integration of rarefaction and extrapolation of Hill numbers was used to compare groups of samples, the microbial diversity (estimated as phylogenetic diversity) differed among individuals reared on different diets, and also between larvae vs. adults. The lowest taxon diversity was found associated with individuals reared on M. chamomilla. Larvae fed with this fiber-rich diet had also a significantly slower development. The composition of the microbial community varied among individuals with different diets, but not between adults vs. larvae. This study highlights the important role of diet in shaping I. inquinata microbiota, but also suggests that the microbiota of non-feeding adult moths could be partially inherited from larvae

Metagenomics approaches for the detection and surveillance of emerging and recurrent plant pathogens

Globalization has a dramatic effect on the trade and movement of seeds, fruits and vegetables, with a corresponding increase in economic losses caused by the introduction of transboundary plant pathogens. Current diagnostic techniques provide a useful and precise tool to enact surveillance protocols regarding specific organisms, but this approach is strictly targeted, while metabarcoding and shotgun metagenomics could be used to simultaneously detect all known pathogens and potentially new ones. This review aims to present the current status of high-throughput sequencing (HTS) diagnostics of fungal and bacterial plant pathogens, discuss the challenges that need to be addressed, and provide direction for the development of methods for the detection of a restricted number of related taxa (specific surveillance) or all of the microorganisms present in a sample (general surveillance). HTS techniques, particularly metabarcoding, could be useful for the surveillance of soilborne, seedborne and airborne pathogens, as well as for identifying new pathogens and determining the origin of outbreaks. Metabarcoding and shotgun metagenomics still suffer from low precision, but this issue can be limited by carefully choosing primers and bioinformatic algorithms. Advances in bioinformatics will greatly accelerate the use of metagenomics to address critical aspects related to the detection and surveillance of plant pathogens in plant material and foodstuffs

The Relationship between Knowing Sign Language and Quality of Life among Italian People Who Are Deaf: A Cross-Sectional Study

Deafness is a medical condition with important relational implications. This conditioncould affect well-being and self-esteem and cause social anxiety. Sign language is not only a simplemimic but can be considered as a different kind of communication that could be protective for thosewho have learned it. However, some people do not use sign language because they think it canbe marginalizing. The present study aimed to compare the quality of life (QoL) between peoplewho learned Italian sign language as their first language with those who had never learned it orlearned it later. This cross-sectional study involved 182 deaf Italian adults (70.3% females) who wererecruited from Ente Nazionale Sordi (ENS) and by the main online deafness groups. The presentresults suggest that the deaf condition does not seem to significantly affect the dimensions of QoLpertaining to satisfaction and self-esteem, while it could have an effect on preventing high levels of social anxiety and in particular, the group who learned Italian sign language showed significantlyless social anxiety than those who had never learned it

The Impact of COVID-19 Pandemic and Lockdown Measures on Quality of Life among Italian General Population

The COVID-19 pandemic that has hit the world in the year 2020 has put a strain on our ability to cope with events and revolutionized our daily habits. On 9 March, Italy was forced to lock down to prevent the spread of the infection, with measures including the mandatory closure of schools and nonessential activities, travel restrictions, and the obligation to spend entire weeks in the same physical space. The aim of this study was to assess the impact of the COVID-19 pandemic and lockdown measures on quality of life (QoL) in a large Italian sample, in order to investigate possible differences in QoL levels related to both demographic and pandemic-specific variables. A total of 2251 Italian adults (1665 women, mainly young and middle adults) were recruited via a snowball sampling strategy. Participants were requested to answer to an online survey, which included demographic and COVID-related information items, and theWorld Health Organization Quality of Life BREF questionnaire (WHOQOL-BREF). The results showed statistically significant differences in QoL depending on a number of variables, including sex, area of residence in Italy, and being diagnosed with a medical/psychiatric condition. To our knowledge, this is the first study to assess QoL during COVID-19 pandemic in Italy, therefore the present findings can offer guidelines regarding which social groups are more vulnerable of a decline in QoL and would benefit of psychological interventions