398 research outputs found

    THE 23 JULY 1930 EARTHQUAKE (MS=6.7) IN THE SOUTHERN APENNINES (ITALY): GEOLOGICAL AND HYDROLOGICAL EFFECTS

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    The 23 July 1930 earthquake (MS=6.7) in the Southern Apennines (Italy) was a catastrophic event that produced many effects such as surface faulting, fractures, landslides, settlements, hydrological changes, variations in chemical/ physical activity related to the volcanic and/or thermal zones and also acoustic and optical phenomena. It is the first great earthquake of the twentieth century that was studied, thanks to the hydrological monitoring network of the Italian Hydrographic Survey (IHS) set up from 1925 to 1929. For this earthquake we analysed the initial IHS hydrometric and pluviometric data, looking for significant anomalies in springs, water wells and mountain streams. Hydrological data relative to rivers, springs and water wells indicate that some changes can be correlated with the earthquake: a post-seismic excess discharge in some streams, pre- and co-seismic decreases in stream flows and water levels in wells, pre- and post-seismic increases in discharges. The pre- and co-seismic stresses and the tectonic deformations were studied in order to find a possible model of interaction between stress state and hydrological variations. The anomalies found in this work can be considered “rebound anomalies”, which are the most common precursor reported by several authors and related to increases in porosity and permeability caused by the fracturing that precedes an earthquake. An estimation of the total excess discharge (0.035 km3) caused by the Ms=6.7 Irpinia earthquake is consistent with the excess discharge of about 0.01 km3 determined for the Mw=6.9 Loma Prieta earthquake. To define the normal hydrodynamic behaviour of the considered aquifers, an analysis of the correlation between rainfalls and water levels and flow rates has been carried out. The delay of significant peaks in the correlograms of figure 7 with respect to the start of the hydrological anomaly and/or its duration, can define the space-time limits of the changes correlated with earthquake

    Hydrological anomalies connected to earthquakes in southern Apennines (Italy)

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    The study of hydrological variations in the watersheds of seismic areas can be useful in order to acquire a new knowledge of the mechanisms by which earthquakes can produce hydrological anomalies. Italy has the availability of many long historical series both of hydrological parameters and of seismological data, and is an ideal laboratory to verify the validity of theoretical models proposed by various authors. In this work we analyse the hydrological anomalies associated with some of the big earthquakes that occurred in the last century in the southern Apennines: 1930, 1980 and 1984. For these earthquakes we analysed hydrometric and pluviometric data looking for significant anomalies in springs, water wells and mountain streams. The influence of rainfalls on the normal flows of rivers, springs and wells has been ascertained. Also, the earthquake of 1805, for which a lot of hydrological perturbations have been reported, is considered in order to point out effects imputable to this earthquake that can be similar to the effects of the other big earthquakes. The considered seismic events exhibit different modes of energy release, different focal mechanisms and different propagation of effects on the invested areas. Furthermore, even if their epicentres were not localised in contiguous seismogenetic areas, it seems that the hydrological effects imputable to them took place in the same areas. Such phenomena have been compared with macroseismic fields and transformed in parameters, in order to derive empirical relationships between the dimensions of the event and the characteristics of the hydrological variations. The results of this work point to a close dependence among hydrological anomalies, regional structures and fault mechanisms, and indicate that many clear anomalies have been forerunners of earthquakes. In 1993, the Naples Bureau of the Hydrographic National Service started the continuous monitoring of hydrologic parameters by a network of automatic stations and transmission in real time; presently 7 acquifers are under control in which also pH, <i>T</i> , salinity, electrical conductivity, dissolved oxygen are measured. We envisage to increase the number of monitoring sites and controlled parameters

    Geochemical monitoring integrated in a real time hydrological network

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    Hydrological data relative to springs and water wells collected by the Hydrografic National Service in Naples indicate that some anomalies can be correlated with the seismic activity in Southern Apennines. In this paper we report some hydrological anomalies for the November 23, 1980 earthquake and suggest that an improvement of the hydrometeorological network of the Hydrographic National Service can reveal geochemical and hydrological anomalies before the earthquakes

    Efficacy of Overground Robotic Gait Training on Balance in Stroke Survivors: A Systematic Review and Meta-Analysis

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    Strokes often lead to a deficit in motor control that contributes to a reduced balance function. Impairments in the balance function severely limit the activities of daily living (ADL) in stroke survivors. The present systematic review and meta-analysis primarily aims to explore the efficacy of overground robot-assisted gait training (o-RAGT) on balance recovery in individuals with stroke. In addition, the efficacy on ADL is also investigated. This systematic review identified nine articles investigating the effects of o-RAGT on balance, four of which also assessed ADL. The results of the meta-analysis suggest that o-RAGT does not increase balance and ADL outcomes more than conventional therapy in individuals after stroke. The data should not be overestimated due to the low number of studies included in the meta-analysis and the wide confidence intervals. Subgroup analyses to investigate the influence of participant’s characteristics and training dosage were not performed due to lack of data availability. Further well-designed randomized controlled trials are needed to investigate the efficacy of o-RAGT on balance in individuals with stroke

    Radon in active volcanic areas of southern Italy

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    The radiogenic gas radon is considered a valid precursor of events like eruptions and earthquakes. We are monitoring the variations in time of this gas in soils and in waters of many active volcanic areas of Southern Italy. The greatest differences in Rn content of the investigated volcanic areas are: Ischia and Campi Flegrei have more Rn than Vesuvio and Vulcano, both in soils and in waters. The thermalized waters of Ischia are enriched in Rn 15 times with respect to soils, while in the other areas soils and underground waters have comparable Rn contents

    Seismically induced ground effects of the 1805, 1930 and 1980 earthquakes in the Southern Apennines (Italy

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    Seismically induced environmental effects (in particular, surfacefaults, ground cracks, slope failures, liquefaction, soil compaction, hydrological changes, tsunamis) are assumed to provide fundamentalinformation on the earthquake size and its intensity field, crucial for a more efficient seismic hazard assessment. Accordingly, this study is aimed at substantiating this assumption by showing that the knowledge about ground effects acquired in recent earthquakes, when combined with that illustrated in historical documents, allows to buildan improved picture of historic seismic events, with respect to that usually provided by the solely damage-based macroseismic scales. In this perspective, the environmental effects are analysed and cataloguedof three of the most ruinous earthquakes in Southern Italy of the last two centuries: the July 26,1805, Molise event (XI MCS, M 6.8), the July 23, 1930, Irpinia event (X MCS, M 6.7), and the November 23, 1980 Campania-Basilicata event (X MSK, Ms 6.9). The distribution of the earthquake environmental effects, in particular their distance from the known or supposed causative fault, has been investigated to obtain a more detailed and comprehensive picture of the macroseismic field, a key parameter in seismic hazard assessment and seismic zonation. KEY WORDS: historical seismicity, intensity, ground effects, earthquak
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